Priority analysis of list variables in ansible playbook and how to separate and summarize list variables

Write it at the front

---

• Um. , Study Ansible Advanced features , Organize this part of the notes
• The content of the blog involves
  • Ansible ploybook Basic principles of variable definition in
  • Define the priority of variables in different positions Demo
  • How to decouple variables from lists
• How to eat ：
  • A lot of Demo, Therefore, it is suitable for collecting, reviewing and looking up variable priority
  • Need to have ansible Basics
  • Understand the basic structure of the role play
  • Able to use Ansible Solve practical problems
• If you don't understand enough, please help me correct

In the evening , You sit under the eaves , Watching the sky slowly darken , My heart is lonely and desolate , Feel deprived of your life . I was a young man , But I'm afraid to live like this , Aging goes on . in my opinion , This is more terrible than death .-------- Wang Xiaobo

---

Manage manifest variables

Describe the basic principles of variables

stay Ansible in , Using variables , You can write Mission 、 Roles and playbook, Make them reusable and flexible . Variables can specify Configuration differences between different systems .ansilbe Variables can be set in many different places ：

• In the role of defaults and vars Directory
• stay Host manifest file in , As Host variables or Group variable
• stay Playbook Or a list of group_vars or host_vars In the variable file under the subdirectory
• stay Play、 role or Mission in

When defining and managing variables in a project , Plan to follow the following principle ：

• Keep it simple ： Although many different ⽅ Formula definition Ansible Variable , But try to use only oneortwo different ways and define variables in only a few places .

• Don't repeat ： If ⼀ Group systems have the same configuration , Then organize them into ⼀ In groups , And in group_vars Set manifest variables for them in the files under the directory .

• Organize variables in small readable files ： If you have a large project with many host groups and variables , Please split the variable into multiple files .

Variable merging and priority

When defining the same variable in multiple ways ,Ansible A priority rule will be used to pick values for variables . Priority is discussed below From low to high ：

• The configuration file (ansible.cfg)
• Command line options
• role defaults Variable
• host and group Variable
• Play Variable
• Extra Variable ( Global variables

Let's briefly sort out these variables together ：

The configuration file

The variables in the configuration file have the lowest priority , By means of ansible.cfg Provide one of KV The key/value pair , Let's look at one Demo

┌──[[email protected]]-[~/ansible]
└─$cat ansible.cfg | grep remote_user
remote_user=root
┌──[[email protected]]-[~/ansible]
└─$

In the configuration file here remote_user=root Is the remote user name to connect to the managed machine , Save the corresponding to ansible Medium ansible_user variable

┌──[[email protected]]-[~/ansible]
└─$ansible vms82.liruilongs.github.io -m debug -a 'var=ansible_user' -i ./inventorys/hosts
vms82.liruilongs.github.io | SUCCESS => {
    
    "ansible_user": "root"
}

Delete the variables in the configuration file ,

┌──[[email protected]]-[~/ansible]
└─$sed -i '/remote_user=root/d' ansible.cfg

When printing variables, you will be prompted that the variables have not been defined

┌──[[email protected]]-[~/ansible]
└─$ansible vms82.liruilongs.github.io -m debug -a 'var=ansible_user' -i ./inventorys/hosts
vms82.liruilongs.github.io | SUCCESS => {
    "ansible_user": "VARIABLE IS NOT DEFINED!"
}

You can also print normally after adding

┌──[[email protected]]-[~/ansible]
└─$sed '4a remote_user=root' ansible.cfg -i
┌──[[email protected]]-[~/ansible]
└─$ansible vms82.liruilongs.github.io -m debug -a 'var=ansible_user' -i ./inventorys/hosts
vms82.liruilongs.github.io | SUCCESS => {
    
    "ansible_user": "root"
}
┌──[[email protected]]-[~/ansible]
└─$

Of course, what we need to pay attention to here is , When the host list is not specified , By default ansible Files with suffixes are ignored

┌──[[email protected]]-[~/ansible]
└─$ansible-config  dump | grep -i inventory
DEFAULT_HOST_LIST(/root/ansible/ansible.cfg) = [u'/root/ansible/inventory']
DEFAULT_INVENTORY_PLUGIN_PATH(default) = [u'/root/.ansible/plugins/inventory', u'/usr/share/ansible/plugins/inventory']
INVENTORY_ANY_UNPARSED_IS_FAILED(default) = False
INVENTORY_CACHE_ENABLED(default) = False
INVENTORY_CACHE_PLUGIN(default) = None
INVENTORY_CACHE_PLUGIN_CONNECTION(default) = None
INVENTORY_CACHE_PLUGIN_PREFIX(default) = ansible_facts
INVENTORY_CACHE_TIMEOUT(default) = 3600
INVENTORY_ENABLED(default) = ['host_list', 'script', 'auto', 'yaml', 'ini', 'toml']
INVENTORY_EXPORT(default) = False
INVENTORY_IGNORE_EXTS(default) = {
    {
    (BLACKLIST_EXTS + ( '.orig', '.ini', '.cfg', '.retry'))}}
INVENTORY_IGNORE_PATTERNS(default) = []
INVENTORY_UNPARSED_IS_FAILED(default) = False
VARIABLE_PRECEDENCE(default) = ['all_inventory', 'groups_inventory', 'all_plugins_inventory', 'all_plugins_play', 'groups_plugins_inventory', 'groups_plugins_play']
┌──[[email protected]]-[~/ansible]
└─$

Command line options ：

Can be passed to on the command line ansible-playbook The option to ( Not -e ) With lowest priority . Here we mainly talk about defining variables through other parameters , Still use what we defined before ansible_user Variable

┌──[[email protected]]-[~/ansible]
└─$ansible all -m debug -a "var=ansible_user"
vms82.liruilongs.github.io | SUCCESS => {
    
    "ansible_user": "root"
}
┌──[[email protected]]-[~/ansible]
└─$ansible all -m debug -a "var=ansible_user" -u liruilong
vms82.liruilongs.github.io | SUCCESS => {
    
    "ansible_user": "liruilong"
}

Of course, what needs to be noted here is that it is executed through temporary commands debug modular . The managed machine is not connected by default , So no error will be reported here , our sanheyiwuyang A user is a user that is not defined by the managed machine .

┌──[[email protected]]-[~/ansible]
└─$ansible all -m debug -a "var=ansible_user" -u sanheyiwuyang
vms82.liruilongs.github.io | SUCCESS => {
    
    "ansible_user": "sanheyiwuyang"
}
┌──[[email protected]]-[~/ansible]
└─$

role default value ：

role_name/defaults/ The default value set by the role in the file has a very low priority . Relative to... In the role vars Variables in the directory , Will be covered defaults A variable's value . Here we still use remote_user This variable

First, create a new role

┌──[[email protected]]-[~/ansible]
└─$ansible-galaxy init vars_demo --init-path=roles
- Role vars_demo was created successfully
┌──[[email protected]]-[~/ansible]
└─$ansible-galaxy list | grep var
- vars_demo, (unknown version)

Write the default variable in the role , Here we define a remote user name that is not defined in the managed machine sanheyiwuyang

┌──[[email protected]]-[~/ansible]
└─$echo -e "ansible_user: sanheyiwuyang" > ./roles/vars_demo/defaults/main.yml
┌──[[email protected]]-[~/ansible]
└─$cat ./roles/vars_demo/defaults/main.yml
ansible_user: sanheyiwuyang
┌──[[email protected]]-[~/ansible]
└─$

Write role tasks

┌──[[email protected]]-[~/ansible]
└─$vim ./roles/vars_demo/tasks/main.yml
┌──[[email protected]]-[~/ansible]
└─$cat ./roles/vars_demo/tasks/main.yml
---
# tasks file for vars_demo
- name: default_vars demo
  debug:
    var: ansible_user
┌──[[email protected]]-[~/ansible]
└─$

Write a script to perform the role

┌──[[email protected]]-[~/ansible]
└─$vim  vars_demo.yaml
┌──[[email protected]]-[~/ansible]
└─$cat vars_demo.yaml
---
- name: vars_demo roles demo
  hosts: all
  roles:
    - vars_demo
  tasks:
    - name: show vars
      debug:
        var: ansible_user
┌──[[email protected]]-[~/ansible]
└─$

Current ansible_user Variable definitions , We can see , The configuration file has the lowest priority , The second is The command line is not (-e) The way

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml  -u liruilong

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
fatal: [vms82.liruilongs.github.io]: UNREACHABLE! => {
    "changed": false, "msg": "Failed to connect to the host via ssh: Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).", "unreachable": true}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=0    changed=0    unreachable=1    failed=0    skipped=0    rescued=0    ignored=0  

┌──[[email protected]]-[~/ansible]
└─$

Execute the script of the calling role , Wrong report , adopt -u The way of specifying liruilong user , But what is used in the role is not liruilong user , It is not defined by the managed machine sanhewuyang user , Because the named line is not -e The priority of variables in the role is lower than that in the role /roles/var_demo/default/main.yaml Variables defined , therefore liruilong The user is overwritten , So there's an error

modify ./roles/vars_demo/defaults/main.yml Medium ansible_user Variable , We can also find that root user , Not the command line liruilong

┌──[[email protected]]-[~/ansible]
└─$echo "ansible_user: root" >  ./roles/vars_demo/defaults/main.yml
┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml  -u liruilong

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0


┌──[[email protected]]-[~/ansible]
└─$

Host variables and group variables ：

For host variables and group variables, this is the corresponding host manifest file , There are many ways to define a host list , We can go straight through inventory File defines , You can also create
inventory Files in the directory to define , You can also define... Under the specified directory in the project , There are many scenes , Let's take a look at

The following list is from Lowest to highest Lists the exact priority of these variables ：

• Set directly in the manifest file or through the dynamic manifest script al Group variable .
• Other group variables set directly in the manifest file or through the dynamic manifest script .
• stay inventory/group_vars/all Set in file or subdirectory all Group variables .
• In the project group_vars/all Set in file or subdirectory all Group variables .
• stay inventory/group_vars Other group variables set in the subdirectory .
• In the project group_vars Other group variables set in the subdirectory .
• Host variables set directly in the manifest file or through the dynamic manifest script .
• stay inventory/host vars Host variables set in subdirectories .
• In the project host vars Host variables set in subdirectories .
• host facts And cached facts.

Let's take a look at them separately ：

Set directly in the manifest file or through the dynamic manifest script all Group variable

┌──[[email protected]]-[~/ansible]
└─$vim inventory/inventory
┌──[[email protected]]-[~/ansible]
└─$cat inventory/inventory
vms82.liruilongs.github.io
[all:vars]
ansible_user=liruilong

The default value in the current role is root

┌──[[email protected]]-[~/ansible]
└─$cat ./roles/vars_demo/defaults/main.yml
ansible_user: root
┌──[r[email protected]]-[~/ansible]
└─$

Through the execution of the script, we can see all Group variables in must have priority over default Variables in the directory

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0  

┌──[[email protected]]-[~/ansible]
└─$

Set directly in the manifest file or through the dynamic manifest script Other group variables .

Based on the above, we create a new group variable [lb:vars]. Definition ansible_user The value of is root

┌──[[email protected]]-[~/ansible]
└─$vim inventory/inventory
┌──[[email protected]]-[~/ansible]
└─$cat inventory/inventory
[lb]
vms82.liruilongs.github.io
[lb:vars]
ansible_user=root
[all:vars]
ansible_user=liruilong

Execute the script and discover , adopt ansible_user The value of is root, The description covers all Set variables in the group

┌──[[email protected]]-[~/ansible]
└─$vim inventory/inventory
┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0


┌──[[email protected]]-[~/ansible]
└─$

stay inventory/group_vars/all Set in file or subdirectory all Group variables

┌──[[email protected]]-[~/ansible]
└─$mkdir -p inventory/group_vars
┌──[[email protected]]-[~/ansible]
└─$echo "ansible_user: liruilong" > inventory/group_vars/all

Will find inventory/group_vars/all Covering the above inventory/inventory Variables defined ,ansible_user The value of is liruilong

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0  

┌──[[email protected]]-[~/ansible]
└─$

stay project Of group_vars/all Set in file or subdirectory all Group variables .

┌──[[email protected]]-[~/ansible]
└─$mkdir group_vars
┌──[[email protected]]-[~/ansible]
└─$echo "ansible_user: root" >  group_vars/all

We will find that the project group_vars/all The following variables will overwrite the host manifest file inventory/group_vars/all Next variable

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0  

┌──[[email protected]]-[~/ansible]
└─$

stay inventory/group_vars Other group variables set in the subdirectory

Here's the thing to note , establish lb Group variable inventory/group_vars/lb.yaml The premise of the document is , Need to be in inventory/inventory Define groups in the file

┌──[[email protected]]-[~/ansible]
└─$cat ./inventory/inventory
[lb]
vms82.liruilongs.github.io

You can see in the inventory/group_vars/lb.yaml The definition in the file overrides

┌──[[email protected]]-[~/ansible]
└─$echo "ansible_user: liruilong" >  inventory/group_vars/lb.yaml
┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0  

┌──[[email protected]]-[~/ansible]
└─$

In the project group_vars Other group variables set in the subdirectory

You can see the of the project ./group_vars/lb.yaml The priority of variables is higher than inventory/group_vars/lb.yaml Under the

┌──[[email protected]]-[~/ansible]
└─$echo "ansible_user: root" > ./group_vars/lb.yaml
┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0  

┌──[[email protected]]-[~/ansible]
└─$

What we analyzed earlier are all group variables , Now let's look at the host variables

Directly in Inventory file Or through a dynamic list script Host variables

┌──[[email protected]]-[~/ansible]
└─$sed  "s/vms82.liruilongs.github.io/& ansible_user=liruilong/" ./inventory/inventory
[lb]
vms82.liruilongs.github.io ansible_user=liruilong
[lb:vars]
ansible_user=root
[all:vars]
ansible_user=liruilong
┌──[[email protected]]-[~/ansible]
└─$sed  "s/vms82.liruilongs.github.io/& ansible_user=liruilong/" ./inventory/inventory -i

Set the host variable to ansible_user=liruilong The priority is higher than the group variable above

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0  

┌──[[email protected]]-[~/ansible]
└─$

stay inventory/host_vars Host variables set in subdirectories

┌──[[email protected]]-[~/ansible]
└─$mkdir inventory/host_vars
┌──[[email protected]]-[~/ansible]
└─$echo "ansible_user: root" > inventory/host_vars/vms82.liruilongs.github.io.yaml

inventory/host_vars The priority of the host variable set in the subdirectory is greater than ./inventory/inventory Host variables in

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0


┌──[[email protected]]-[~/ansible]
└─$

In the project host_vars Host variables set in subdirectories

┌──[[email protected]]-[~/ansible]
└─$mkdir  host_vars
┌──[[email protected]]-[~/ansible]
└─$echo "ansible_user: liruilong" > host_vars/vms82.liruilongs.github.io.yaml

Project host_vars The priority of host variables set in the subdirectory is higher than that in the list host_vars Variables of subdirectories

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0  

┌──[[email protected]]-[~/ansible]
└─$

host facts And cached facts

host facts, You can see set_fact The variables set have the highest priority

┌──[[email protected]]-[~/ansible]
└─$cat vars_demo.yaml
---
- name: vars_demo roles demo
  hosts: all
  roles:
    - vars_demo
  tasks:
    - name: show vars
      debug:
        var: ansible_user
    - name: set fact ansible_user
      set_fact:
         ansible_user: root
    - name: show vars
      debug:
        var: ansible_user

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [set fact ansible_user] ***************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=5    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

For others, some pass gather_facts Collected variables , It has a high priority over the outside of the script

Relative to the list inventory Of group_vars and host_vars Subdirectories are relative to playbook The priority between the subdirectories of the project is easy to distinguish , The same type , Projects always have a higher priority than the list ,.

If in playbook In the same directory as group_vars and host_vars subdirectories , Then these group and host variables will be automatically included .

Just to summarize ansible Manifest file variable priority . stay facts The highest priority , The second is host variables , Contains the manifest variable file host_vars Contents and inventory List variable directory and inventory file , Items should be higher than the list , The list directory should be higher than the list file , Then there is a group of variables ,group_vars A file in a directory ,inventory Manifest Variable Directory ,inventory file , On the whole ,inventory The priority of the file is lower than that of the directory , The same is inventory The directory should be smaller than the project directory .

Play Variable ：

preparation , We also use the previous roles and scripts

┌──[[email protected]]-[~/ansible]
└─$cat vars_demo.yaml
---
- name: vars_demo roles demo
  hosts: all
  roles:
    - vars_demo
  tasks:
    - name: show vars
      debug:
        var: ansible_user
    - name: show vars
      debug:
        var: ansible_user
┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=4    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Play Has a higher priority than Host or group variables 、 Role defaults , except -e Command line options other than . The following list lists the priority of these variables from the lowest to the highest ：

• from play Of vars Set in part .
• adopt play Medium vars_prompt Part prompts the user to set .
• adopt play Of vars_files Some settings are made from the external file list .
• By role rolename/vars/ Set the files in the subdirectory .
• Through this block vars Part is the current block Set it up .
• Through this task vars Part is set for the current task .
• adopt include_vars Module dynamic loading .
• By using set_fact Module or by using register Record the results of task execution on the host , Set up for a specific host .
• stay play Of role Partially loaded or by using include_role modular playbook Parameters set for roles in .
• from vars Partly through include_tasks Set the tasks contained in the module .

Let's sort out ：

from play Of vars Set in part .

---
- name: vars_demo roles demo
  hosts: all
  vars:
    ansible_user: root
  roles:
    - vars_demo
  tasks:
    - name: show vars
      debug:
        var: ansible_user
    - name: show vars
      debug:
        var: ansible_user

play Of vars Part of the variables to be set are higher than the previously set variables

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=4    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

adopt play Medium vars_prompt Part prompts the user to set

---
- name: vars_demo roles demo
  hosts: all
  vars:
    ansible_user: root
  vars_prompt:
    - name: ansible_user
      prompt: "input ansible_user name"
  roles:
    - vars_demo
  tasks:
    - name: show vars
      debug:
        var: ansible_user
    - name: show vars
      debug:
        var: ansible_user

By default, the input data is not displayed , You can add parameters private: no To display the value of the input variable

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml
input ansible_user name:

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=4    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0  

adopt play Of vars_files Some settings are made from the external file list

---
- name: vars_demo roles demo
  hosts: all
  vars:
    ansible_user: root
  vars_files:
    - vars_files
  vars_prompt:
    - name: ansible_user
      prompt: "input ansible_user name"
      private: no
  roles:
    - vars_demo
  tasks:
    - name: show vars
      debug:
        var: ansible_user
    - name: show vars
      debug:
        var: ansible_user

Define the imported variable file

┌──[[email protected]]-[~/ansible]
└─$echo "ansible_user: liruilong" > vars_files

Execute the script , You can see that what we entered is root But what's printed is liruilong, namely vars_files Has a higher priority than vars_prompt

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml
input ansible_user name: root

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=4    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

By role rolename/vars/ Set the files in the subdirectory

The variable value returned by the current script execution is liruilong, We define roles/vars_demo/vars/main.yml The directory ansible_user Variable is root. Execute the script

┌──[[email protected]]-[~/ansible]
└─$echo "ansible_user: root" > roles/vars_demo/vars/main.yml
┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************************************

TASK [Gathering Facts] *********************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars] ***************************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

PLAY RECAP *********************************************************************************************************
vms82.liruilongs.github.io : ok=4    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Through this task block vars Part is the current block Set it up .

---
- name: vars_demo roles demo
  hosts: all
  roles:
    - vars_demo
  tasks:
    - block:
        - name: show vars in block
          debug:
            var: ansible_user
      vars:
        ansible_user: liruilong
    - name: show vars
      debug:
        var: ansible_user

We can see , stay block Inside the block where it is located , adopt vars Variables defined have the highest priority , Printed ansible_usern The of the variable is liruilong, The variables printed in other parts of the script are root

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook var_demos.yaml

PLAY [vars_demo roles demo] ****************************************************************

TASK [Gathering Facts] *********************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars in block] ******************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [show vars] ***************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

PLAY RECAP *********************************************************************************
vms82.liruilongs.github.io : ok=4    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

show vars The task is the task in the role , So we still use the characters vars/main.yml Definition root.

Through this task vars Part is set for the current task

It is not written in block In block vars Variable , It's written in the corresponding In the task vars Variables in

---
- name: vars_demo roles demo
  hosts: all
  roles:
    - vars_demo
  tasks:
    - block:
        - name: show vars in block
          debug:
            var: ansible_user
          vars:
            ansible_user: root
        - name: show vars  in block no vars
          debug:
            var: ansible_user
      vars:
        ansible_user: liruilong

Execution we can see in block Inside , Variables inside the task have higher priority than variables outside the task .

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************

TASK [Gathering Facts] *********************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars in block] ******************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars  in block no vars] *********************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

PLAY RECAP *********************************************************************************
vms82.liruilongs.github.io : ok=4    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

adopt include_vars Module dynamic loading

stay ansible in , We can use include_vars Module to load external variables . The loading method is simple , And through the play Of vars_files Part of the setup from the external file list is very similar .

---
- name: vars_demo roles demo
  hosts: all
  roles:
    - vars_demo
  tasks:
    - block:
        - name: show vars in block
          debug:
            var: ansible_user
          vars:
            ansible_user: root
        - name: show vars  in block no vars
          debug:
            var: ansible_user
      vars:
        ansible_user: liruilong
    - name: show vars
      debug:
         var: ansible_user

    - name: include_vars vars file
      include_vars:
         file: vars_files
    - name: show vars after include vars files
      debug:
         var: ansible_user

But the priority of variables is very different , Let's put the include_vars Put the module to the end and see .

┌──[[email protected]]-[~/ansible]
└─$cat vars_files
ansible_user: liruilong
┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************

TASK [Gathering Facts] *********************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars in block] ******************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars  in block no vars] *********************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [show vars] ***************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [include_vars vars file] **************************************************************
ok: [vms82.liruilongs.github.io]

TASK [show vars after include vars files] **************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

PLAY RECAP *********************************************************************************
vms82.liruilongs.github.io : ok=7    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

It is found that there is no change before the module is executed , It will only affect the after execution .

---
- name: vars_demo roles demo
  hosts: all
  roles:
    - vars_demo
  tasks:
    - name: include_vars vars file
      include_vars:
         file: vars_files
    - block:
        - name: show vars in block
          debug:
            var: ansible_user
          vars:
            ansible_user: root
        - name: show vars  in block no vars
          debug:
            var: ansible_user
      vars:
        ansible_user: liruilong
    - name: show vars
      debug:
         var: ansible_user

    - name: show vars after include vars files
      debug:
         var: ansible_user

hold include_vars Put the module to the front , We found that all the variables in the script were replaced with liruilong 了 , Except for role variables , Because in the script , The role is executed first .

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************

TASK [Gathering Facts] *********************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [include_vars vars file] **************************************************************
ok: [vms82.liruilongs.github.io]

TASK [show vars in block] ******************************************************************
ok: [vms82.liruilongs.github.io] =>
    "ansible_user": "liruilong"
}

TASK [show vars  in block no vars] *********************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [show vars] ***************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [show vars after include vars files] **************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

PLAY RECAP *********************************************************************************
vms82.liruilongs.github.io : ok=7    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

By using set_fact modular Or by using register Record the results of task execution on the host , Set up for a specific host .

---
- name: vars_demo roles demo
  hosts: all
  roles:
    - vars_demo
  tasks:
    - name: set facts
      set_fact:
        ansible_user: root
    - name: include_vars vars file
      include_vars:
         file: vars_files
    - block:
        - name: show vars in block
          debug:
            var: ansible_user
          vars:
            ansible_user: root
        - name: show vars  in block no vars
          debug:
            var: ansible_user
      vars:
        ansible_user: liruilong
    - name: show vars
      debug:
         var: ansible_user

    - name: show vars after include vars files
      debug:
         var: ansible_user

Um. , Not much to explain .

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************

TASK [Gathering Facts] *********************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [set facts] ***************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [include_vars vars file] **************************************************************
ok: [vms82.liruilongs.github.io]

TASK [show vars in block] ******************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars  in block no vars] *********************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars] ***************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars after include vars files] **************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

PLAY RECAP *********************************************************************************
vms82.liruilongs.github.io : ok=8    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

stay play Of role Partially loaded or by using include_role modular playbook Parameters set for roles in .

---
- name: vars_demo roles demo
  hosts: all
  roles:
    - role: vars_demo
      ansible_user: liruilong
  tasks:
    - name: set facts
      set_fact:
        ansible_user: root
    - name: include_vars vars file
      include_vars:
         file: vars_files
    - block:
        - name: show vars in block
          debug:
            var: ansible_user
          vars:
            ansible_user: root
        - name: show vars  in block no vars
          debug:
            var: ansible_user
      vars:
        ansible_user: liruilong
    - name: show vars
      debug:
         var: ansible_user

    - name: show vars after include vars files
      debug:
         var: ansible_user

After the script sets the role variable , The built-in variable is overwritten , But only for the current role

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************************

TASK [Gathering Facts] *********************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [vars_demo : default_vars demo] *******************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [set facts] ***************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [include_vars vars file] **************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [show vars in block] ******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars  in block no vars] *********************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars] ***************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars after include vars files] **************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

PLAY RECAP *********************************************************************************************
vms82.liruilongs.github.io : ok=8    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Or maybe

---
- name: vars_demo roles demo
  hosts: all
 # roles:
 # - role: vars_demo
 # ansible_user: liruilong
  tasks:
    - name: include role
      include_role:
        name: vars_demo
      vars:
         ansible_user: liruilong
    - name: set facts
      set_fact:
        ansible_user: root
    - name: include_vars vars file
      include_vars:
         file: vars_files
    - block:
        - name: show vars in block
          debug:
            var: ansible_user
          vars:
            ansible_user: root
        - name: show vars  in block no vars
          debug:
            var: ansible_user
      vars:
        ansible_user: liruilong
    - name: show vars
      debug:
         var: ansible_user

    - name: show vars after include vars files
      debug:
         var: ansible_user

┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************************

TASK [Gathering Facts] *********************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [include role] ************************************************************************************

TASK [vars_demo : default_vars demo] *******************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "liruilong"
}

TASK [set facts] ***************************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [include_vars vars file] **************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [show vars in block] ******************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars  in block no vars] *********************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars] ***************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

TASK [show vars after include vars files] **************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

PLAY RECAP *********************************************************************************************
vms82.liruilongs.github.io : ok=8    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

from vars Partly through include_tasks Set the tasks contained in the module

---
- name: vars_demo roles demo
  hosts: all
 # roles:
 # - role: vars_demo
 # ansible_user: liruilong
  tasks:
    - name: include_tasks demo
      include_tasks: task.yaml
      vars:
        ansible_user: root
    - name: include role
...

┌──[[email protected]]-[~/ansible]
└─$cat task.yaml
- name: vars demo 2
  debug:
    var: ansible_user
┌──[[email protected]]-[~/ansible]
└─$ansible-playbook vars_demo.yaml

PLAY [vars_demo roles demo] ****************************************************************************

TASK [Gathering Facts] *********************************************************************************
ok: [vms82.liruilongs.github.io]

TASK [include_tasks demo] ******************************************************************************
included: /root/ansible/task.yaml for vms82.liruilongs.github.io

TASK [vars demo 2] *************************************************************************************
ok: [vms82.liruilongs.github.io] => {
    
    "ansible_user": "root"
}

....

Extra Variable (-e Order or –extra-vars)

Use ansible-playbook Ordered -e The extra variables set by the option always have the highest priority . perhaps --extra-vars You can also use JSON Formal definition

┌──[[email protected]]-[~/ansible]
└─$ansible vms82.liruilongs.github.io -m debug -a 'var=ansible_user'
vms82.liruilongs.github.io | SUCCESS => {
    
    "ansible_user": "root"
}
┌──[[email protected]]-[~/ansible]
└─$ansible all -m debug -a "var=ansible_user" --extra-vars "{'ansible_user':'liruilong'}"
vms82.liruilongs.github.io | SUCCESS => {
    
    "ansible_user": "liruilong"
}
┌──[[email protected]]-[~/ansible]
└─$ansible all -m debug -a "var=ansible_user" --e "{'ansible_user':'liruilong'}"
vms82.liruilongs.github.io | SUCCESS => {
    
    "ansible_user": "liruilong"
}

Can be found when using --extra-vars When defining variables on the command line , Will be covered ansible.cfg Variable configuration for , Used liruilong This managed machine user

Separate variables from lists

As the environment expands in size and variety , The manifest file can become large and difficult to read .

It is better to move the variable definition from the manifest file to a separate variable file , Each host group corresponds to one , Each variable file has host group commands , And contains the variable definitions of the host group ：

For a diversified and large-scale environment , A better way is to group_vars Create subdirectories for each host group under the directory ：

┌──[[email protected]]-[~/inventory-variables]
└─$ls
ansible.cfg        deploy_haproxy.yml  group_vars     roles
deploy_apache.yml  deploy_webapp.yml   inventory.yml  site.yml
┌──[[email protected]]-[~/inventory-variables]
└─$cd group_vars/
┌──[[email protected]]-[~/inventory-variables/group_vars]
└─$tree
.
├── lb_servers
│   ├── firewall.yml
│   └── haproxy.yml
└── web_servers

2 directories, 2 files

group_vars Catalog All variables existing in the files in each directory under are merged with other variables ⼀ rise . By separating variables into files grouped by function , Can make the whole playbook Projects are easier to understand and maintain .

Special list variables

You can use multiple variables to change Ansible How to connect to the hosts listed in the list . among ⼀ Some are most useful for host specific variables , But another ⼀ These may be related to all hosts in the group or in the list .

ansible_connection： The connection type of the host , Connection plug-ins for accessing managed hosts . By default ,ssh Used in addition to localhost All hosts outside , The latter uses local.

┌──[[email protected]]-[~/ansible]
└─$ansible all -m debug -a "msg={
    {ansible_connection}}"
vms82.liruilongs.github.io | SUCCESS => {
    
    "msg": "ssh"
}
┌──[[email protected]]-[~/ansible]
└─$ansible 127.0.0.1  -m debug -a "msg={
    {ansible_connection}}"
127.0.0.1 | SUCCESS => {
    
    "msg": "local"
}

ansible_host： Host name to connect to . actual IP Address or fully qualified domain name , Use when connecting to a managed host , Instead of using it from the manifest file (inventory_hostname) The name of the . By default , This variable has the same value as the manifest hostname .

┌──[[email protected]]-[~/ansible]
└─$ansible all -m debug -a "msg={
    {ansible_host}}"
vms82.liruilongs.github.io | SUCCESS => {
    
    "msg": "vms82.liruilongs.github.io"
}

• ansible_port：Ansible The port used to connect the managed host . about （ Default ）SSH Connect plug-ins , The default value is 22.
• ansible_user：Ansible Connect to the managed host as this user . As Ansible Default behavior of , It will use and run on the control node Ansible Playbook Connect to the managed host with the same user name .
• ansible_become_user：Ansible After connecting to the managed host , It will use ansible_become_method（ By default sudo） Switch to this user .
• ansible_python_interpreter：Ansible Should be used on managed hosts Python Path to executable file .

System variables ： Through the script gather_facts=yes Automatic collection （ Default call setup modular ）, Valid for task host , System indicators

┌──[[email protected]]-[~/ansible]
└─$ansible  all  -m  setup

Use variables to identify the current host

ansible Magic variable , refer to ansible Special variables preset for management purposes , adopt adhoc Way or playbook The way , You can call / perhaps msg see

• inventory_hostname： Name of the managed host currently being processed , Get... From the list .
• ansible_host： The actual server used to connect the managed host IP Address or host name .
• ansible_facts[‘hostname’]： As a matter of fact , From the fully qualified domain name of the managed host phone .
• ansible_play_hosts： At present Play List of all hosts that have not failed during .

┌──[[email protected]]-[~/ansible]
└─$ansible  all  -m  debug -a "var=hostvars"
vms82.liruilongs.github.io | SUCCESS => {
    
    "hostvars": {
    
        "vms82.liruilongs.github.io": {
    
            "ansible_check_mode": false,
            "ansible_diff_mode": false,
            "ansible_facts": {
    },
            "ansible_forks": 5,
            "ansible_inventory_sources": [
                "/root/ansible/inventory"
            ],
            "ansible_playbook_python": "/usr/bin/python2",
            "ansible_user": "liruilong",
            "ansible_verbosity": 0,
            "ansible_version": {
    
                "full": "2.9.25",
                "major": 2,
                "minor": 9,
                "revision": 25,
                "string": "2.9.25"
            },
            "group_names": [
                "lb"
            ],
            "groups": {
    
                "all": [
                    "vms82.liruilongs.github.io"
                ],
                "lb": [
                    "vms82.liruilongs.github.io"
                ],
                "ungrouped": []
            },
            "inventory_dir": "/root/ansible/inventory",
            "inventory_file": "/root/ansible/inventory/hosts",
            "inventory_hostname": "vms82.liruilongs.github.io",
            "inventory_hostname_short": "vms82",
            "omit": "__omit_place_holder__fbd943e37b3564fcd7926f8926da009ae4e9e4ab",
            "playbook_dir": "/root/ansible"
        }
    }
}

A complete Demo

Um. , Let's look at a specific Demo, this Demo It is used in previous blog posts , Take a look at how to start from the existing ansible Extract variables from the project to realize the reusability of the script , Maintainable

This is the original structure directory

┌──[[email protected]]-[~/ansible/inventory-variables]
└─$tree
.
├── ansible.cfg
├── deploy_apache.yml
├── deploy_haproxy.yml
├── deploy_webapp.yml
├── inventory.yml
├── roles
│   ├── apache
│   │   ├── meta
│   │   │   └── main.yml
│   │   ├── tasks
│   │   │   └── main.yml
│   │   └── tests
│   │       ├── inventory
│   │       └── test.yml
│   ├── firewall
│   │   ├── defaults
│   │   │   └── main.yml
│   │   ├── handlers
│   │   │   └── main.yml
│   │   ├── meta
│   │   │   └── main.yml
│   │   ├── tasks
│   │   │   └── main.yml
│   │   └── tests
│   │       ├── inventory
│   │       └── test.yml
│   ├── haproxy
│   │   ├── defaults
│   │   │   └── main.yml
│   │   ├── handlers
│   │   │   └── main.yml
│   │   ├── meta
│   │   │   └── main.yml
│   │   ├── tasks
│   │   │   └── main.yml
│   │   ├── templates
│   │   │   └── haproxy.cfg.j2
│   │   └── tests
│   │       ├── inventory
│   │       └── test.yml
│   └── webapp
│       ├── defaults
│       │   └── main.yml
│       ├── meta
│       │   └── main.yml
│       ├── tasks
│       │   └── main.yml
│       └── tests
│           ├── inventory
│           └── test.yml
└── site.yml

30 directories, 34 files
┌──[[email protected]]-[~/ansible/inventory-variables]
└─$

This is what we have rewritten , You'll find one more group_vars Catalog

┌──[[email protected]]-[~/ansible/inventory-variables]
└─$tree
.
├── ansible.cfg
├── deploy_apache.yml
├── deploy_haproxy.yml
├── deploy_webapp.yml
├── group_vars
│   ├── lb_servers
│   │   ├── firewall.yml
│   │   └── haproxy.yml
│   └── web_servers
├── inventory.yml
├── roles
│   ├── apache
│   │   ├── meta
│   │   │   └── main.yml
│   │   ├── tasks
│   │   │   └── main.yml
│   │   └── tests
│   │       ├── inventory
│   │       └── test.yml
│   ├── firewall
│   │   ├── defaults
│   │   │   └── main.yml
│   │   ├── handlers
│   │   │   └── main.yml
│   │   ├── meta
│   │   │   └── main.yml
│   │   ├── tasks
│   │   │   └── main.yml
│   │   └── tests
│   │       ├── inventory
│   │       └── test.yml
│   ├── haproxy
│   │   ├── defaults
│   │   │   └── main.yml
│   │   ├── handlers
│   │   │   └── main.yml
│   │   ├── meta
│   │   │   └── main.yml
│   │   ├── tasks
│   │   │   └── main.yml
│   │   ├── templates
│   │   │   └── haproxy.cfg.j2
│   │   └── tests
│   │       ├── inventory
│   │       └── test.yml
│   ├── org_common
│   │   ├── meta
│   │   │   └── main.yml
│   │   ├── tasks
│   │   │   └── main.yml
│   │   └── tests
│   │       ├── inventory
│   │       └── test.yml
│   └── webapp
│       ├── defaults
│       │   └── main.yml
│       ├── meta
│       │   └── main.yml
│       ├── tasks
│       │   └── main.yml
│       └── tests
│           ├── inventory
│           └── test.yml
└── site.yml

30 directories, 34 files

Let's take a look at this Demo, About what the script did , You can take a look at my previous ansible post

Create a new... In the project root group_vars , Create subdirectories for each host group under this directory

┌──[[email protected]]-[/home/student/git-repos/inventory-variables]
└─$mkdir group_vars

establish lb_servers ⽬ record , To store lb_servers Variables of hosts in the Group

┌──[[email protected]]-[/home/student/git-repos/inventory-variables]
└─$mkdir group_vars/lb_servers

establish web_servers ⽬ record , To store web_servers Group variables

┌──[[email protected]]-[/home/student/git-repos/inventory-variables]
└─$ mkdir group_vars/web_servers

Define variable files in each host group for the roles involved

┌──[[email protected]]-[/home/student/git-repos/inventory-variables]
└─$touch group_vars/lb_servers/firewall.yml
┌──[[email protected]]-[/home/student/git-repos/inventory-variables]
└─$touch group_vars/lb_servers/haproxy.yml
┌──[[email protected]]-[/home/student/git-repos/inventory-variables]
└─$ls

In execution deploy_haproxy When the script , call haproxy, It will involve the loading of role related variables .firewall_rules,haproxy_appservers These two role variables .firewall Roles are executed in a role dependent manner , and haproxy Execute directly through the script

┌──[[email protected]]-[/home/student/git-repos/inventory-variables]
└─$cat deploy_haproxy.yml
- name: Ensure HAProxy is deployed
  hosts: lb_servers
  force_handlers: True

  roles:
    # The "haproxy" role has a dependency on the "firewall" role.
    # The "firewall" role requires a "firewall_rules" variable be defined.
    - role: haproxy
      firewall_rules:
        # Allow 80/tcp connections
        - port: 80/tcp

      haproxy_appservers:
      - name: serverb.lab.example.com
        ip: 172.25.250.11
        backend_port: 80
      - name: serverc.lab.example.com
        ip: 172.25.250.12
        backend_port: 80

stay group_vars/lb_servers/firewall.yml Define host groups lb_servers It's about firewall Role variables

┌──[[email protected]]-[/home/student/git-repos/inventory-variables]
└─$tee group_vars/lb_servers/firewall.yml <<- EOF
> firewall_rules:
>    # Allow 80/tcp connections
>    - port: 80/tcp
> EOF
firewall_rules:
   # Allow 80/tcp connections
   - port: 80/tcp
┌──[[email protected]ation.lab.example.com]-[/home/student/git-repos/inventory-variables]
└─$

At the same time, delete the variables in the script

┌──[[email protected]]-[/home/student/git-repos/inventory-variables]
└─$cat deploy_haproxy.yml
- name: Ensure HAProxy is deployed
  hosts: lb_servers
  force_handlers: True

  roles:
    # The "haproxy" role has a dependency on the "firewall" role.
    # The "firewall" role requires a "firewall_rules" variable be defined.
    - role: haproxy
      haproxy_appservers:
      - name: serverb.lab.example.com
        ip: 172.25.250.11
        backend_port: 80
      - name: serverc.lab.example.com
        ip: 172.25.250.12
        backend_port: 80

The same in lb_servers Under the host group directory haproxy Role variables are defined in the file haproxy Variables involved in the role

┌──[[email protected]]-[/home/student/git-repos/inventory-variables]
└─$tee  group_vars/lb_servers/haproxy.yml <<- EOF
> haproxy_appservers:
>    - name: serverb.lab.example.com
>      ip: 172.25.250.11
>      backend_port: 80
>    - name: serverc.lab.example.com
>      ip: 172.25.250.12
>      backend_port: 80
> EOF
haproxy_appservers:
   - name: serverb.lab.example.com
     ip: 172.25.250.11
     backend_port: 80
   - name: serverc.lab.example.com
     ip: 172.25.250.12
     backend_port: 80
┌──[[email protected]]-[/home/student/git-repos/inventory-variables]
└─$

┌──[[email protected]]-[/home/student/git-repos/inventory-variables]
└─$cat deploy_haproxy.yml
- name: Ensure HAProxy is deployed
  hosts: lb_servers
  force_handlers: True

  roles:
    # The "haproxy" role has a dependency on the "firewall" role.
    # The "firewall" role requires a "firewall_rules" variable be defined.
    - role: haproxy

Through the above transformation , We decouple variables from the script that performs the role , This is similar to the way that static variable data is extracted from the code by loading the configuration file . If the script of the calling character is complicated , That's by pulling the variables away , Every time you need to maintain or migrate, you can directly modify the variable file .

alike deploy_apache Let's replace the script variables in the same way .

┌──[[email protected]]-[/home/student/git-repos/inventory-variables]
└─$ cat deploy_apache.yml
- name: Ensure Apache is deployed
  hosts: web_servers
  force_handlers: True

  roles:
    # The "apache" role has a dependency on the "firewall" role.
    # The "firewall" role requires a "firewall_rules" variable be defined.
    - role: apache
      firewall_rules:
        # Allow http requests from the load_balancer.
        - zone: internal
          service: http
          source: "172.25.250.10"
┌──[[email protected]]-[/home/student/git-repos/inventory-variables]
└─$tee group_vars/web_servers/firewall.yml <<- EOF
> firewall_rules:
>    # Allow http requests from the load_balancer.
>    - zone: internal
>      service: http
>      source: "172.25.250.10"
> EOF
firewall_rules:
   # Allow http requests from the load_balancer.
   - zone: internal
     service: http
     source: "172.25.250.10"
┌──[[email protected]]-[/home/student/git-repos/inventory-variables]
└─$

- name: Ensure Apache is deployed
  hosts: web_servers
  force_handlers: True

  roles:
    # The "apache" role has a dependency on the "firewall" role.
    # The "firewall" role requires a "firewall_rules" variable be defined.
    - role: apache

There are more directories after the transformation

┌──[[email protected]]-[/home/student/git-repos/inventory-variables/group_vars]
└─$tree
.
├── lb_servers
│   ├── firewall.yml
│   └── haproxy.yml
└── web_servers
    └── firewall.yml

2 directories, 3 files

At the same time, we rewrite the host manifest file

The playbook Send the list to the host load_balancer Deploy as a load balancer , And group web_servers The host in is the back end Web Server to deploy .
edit inventory.yml Static list ⽂ Pieces of , In order to playbook Middle quotation ⽤ load_balancer When the host is running Ansible Connect to servera.lab.example.com. List host serverb.lab.example.com and serverc.lab.example.com Should be in group web_servers in .

lb_servers:
  hosts:
    servera.lab.example.com:

web_servers:
  hosts:
    server[b:c].lab.example.com:

lb_servers:
  hosts:
    load_balancer:
      ansible_host: servera.lab.example.com

web_servers:
  hosts:
    server[b:c].lab.example.com:

The above is the original manifest file , The following is our rewritten manifest file , Through here ansible_host The Manifest Variable specifies the machine at execution time , And defines an alias load_balancer, in other words , In the host list is lb_servers When the group executes the script , When connecting the managed host , Use the currently defined alias . adopt DNS To map to the corresponding machine , Instead of using it from the manifest file (inventory_hostname) The name of the .

Organize reference books

《RED HAT 447 Advanced Automation:Ansible Best Practices Edition》