Kubernetes understands kubectl/ debugging

understand kubectl /kubectl Command and kubeconfig

---

kubectl Allows us to communicate with... In a command-line fashion kuberneted Interact , This command line can give it some parameters and input files , These documents are prepared one by one kubernetes object , These files are read by it , In essence, it is equivalent to a converter , He will convert the object to rest call .（kubernetes apiserver It's a server）,kubelctl Is to accept these instructions , And convert the instructions into rest Call passed to apiserver.

-v 9 On behalf of this order log The level of 9. You can see that it is loaded by default kubecobnfig

[[email protected] ~]# kubectl get pod -v 9
I0623 17:09:34.998578   73360 loader.go:375] Config loaded from file:  /root/.kube/config
I0623 17:09:35.013322   73360 round_trippers.go:423] curl -k -v -XGET  -H "Accept: application/json, */*" -H "User-Agent: kubectl/v1.19.0 (linux/amd64) kubernetes/e199641" 'https://192.168.111.6:6443/api?timeout=32s'
I0623 17:09:35.041788   73360 round_trippers.go:443] GET https://192.168.111.6:6443/api?timeout=32s 200 OK in 28 milliseconds
I0623 17:09:35.041813   73360 round_trippers.go:449] Response Headers:

This kubeconfig Itself is a configuration file , You can configure many cluster, Every cluster Have your own name , The most important thing is server.

- cluster:
    certificate-authority-data: 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
    server: https://192.168.111.6:6443
  name: kubernetes

context Is the context of the configuration , It specifies to connect k8s Which cluster among them , Because you can configure multiple cluster. Second, which user to use to access it , The user information is below user part , The second is context What's your name , Currently called [email protected]

contexts:
- context:
    cluster: kubernetes
    user: kubernetes-admin
  name: [email protected]
current-context: [email protected]
kind: Config
preferences: {}

User information

users:
- name: kubernetes-admin
  user:
    client-certificate-data: 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

 

 

Kubectl Common commands

---

Etcd In addition to being a database , It is also a message oriented middleware , It will push messages to apiserver,apiserver Inherited the same abilities , On the one hand is list watch etcd, It also provides the same service .

Other components include kubectl You can also go. watch apiserver,apiserver There is any change of events here , In fact, it can be notified .

[[email protected] ~]# kubectl get pod -w
NAME                           READY   STATUS    RESTARTS   AGE
dns-test                       1/1     Running   3          37d
nginx-74d69c5bbb-6478r         1/1     Running   3          35d
nginx-74d69c5bbb-mhmsc         1/1     Running   3          35d
nginx-web-0                    1/1     Running   4          37d
nginx-web-1                    1/1     Running   0          16h
web-mychart-7d8f9bd8d6-jfdc9   1/1     Running   0          38m

adopt watch You can know the changes of this object in real time , All components of the cluster operate through this mechanism .

Everybody go to watch apiserver, Please let me know if there is any incident .

 

 

 

Kubectl Debug command /describe

---

Want to know pod What happened? , Want to know pod Changes in events , This event contains the details of the container itself , And its related events event.

event stay k8s It's actually another object , This object is associated with a master object when it is created .

from You can see who sent the event , It is sent by the scheduler and bound with the node event, This is equivalent to me event Creating pod There is a relationship between them .

The second is kubelet Produced event, With event Create... Under formal records pod Log information , It's for this pod Create a event object .

describe When , First, it pulls down the main object , Secondly, it will pull the related... Of the main object event object , Then make an integrated presentation .

therefore describe You can see the events related to this object .

Events:
  Type    Reason     Age   From            Message
  ----    ------     ----  ----            -------
  Normal  Scheduled  57s                   Successfully assigned default/nginx-web-0 to node2
  Normal  Pulled     92s   kubelet, node2  Container image "nginx:1.11" already present on machine
  Normal  Created    92s   kubelet, node2  Created container nginx-test
  Normal  Started    92s   kubelet, node2  Started container nginx-test

 

 

Kubectl Debug command /exec

---

exec Whether you can use it depends on how you mirror the container and build it , What is the container base image , What debugging tools are provided , If it's a scrach, There's nothing in there , You can't run any command , Then you can only debug on the host .

 

 

Kubetcl Debug command /logs

---

  If pod There are several containers in it , Then you can use -c To specify which container log to view .