Introduction: from the origin of etcd name to installation, deployment and usage posture

Hello everyone , I am a Thirty-one ^[0], This time, we share the distributed artifact etcd^[1] Of 5 Deployment methods and 10 Three use postures , Estimated cost of reading the full text 16 minute . If it helps you , You are also welcome to like the collection .

I'm learning etcd Before , Let's talk about it first etcd The origin of the name ^[2].etcd Medium etc Taken from the unix Systematic /etc Catalog , Add one more d representative distributed system It makes up etcd. stay unix In the system /etc The directory is used to store the configuration data of the system , Just by name etcd It can be used to store configuration data of distributed systems , Sometimes I put etcd It is simply understood as distributed /etc The configuration directory .

etcd brief introduction

etcd It's a reliable distributed key-value The storage system , It is mainly used for Configure sharing and Service registration and discovery , It has the following characteristics ：

• Simple ： be based on gRPC Clearly defined 、 User oriented API.
• Security ： Support for optional clients TLS Automatic certificate authentication feature .
• Fast ： Support per second 10000 Second write .
• reliable ： be based on Raft The algorithm protocol guarantees consistency .

etcd Use Go Language development , Bottom based Raft The consensus algorithm manages highly available replication logs . It has been used by many companies for key production projects , such as ：Kubernetes、locksmith、vulcand、Doorman etc. .

Of course , There are also other components that can provide the functions of configuration sharing and service registration and discovery , For example, the most extensive and well-known Zookeeper, And a lot of Java Recognized and used by well-known open source projects of the Department , such as ：Hadoop、HBase、Kafka etc. .

but etcd Is the only one that can rival or even surpass Zookeeper The components of .

By contrast ,Zookeeper It has the following disadvantages [3]：

• complex ：Zookeeper be based on ZAB agreement , Belong to category Paxos agreement , and Paxos Algorithms are known for their complexity ;Zookeeper The use of is also complex , The client needs to be installed , At present, the official only provides Java and C Two language interface .
• Slow development ： Due to the huge structure and loose management of the foundation , This leads to the slow development of the project .

and etcd As a rising star , Its advantages are obvious ：

• Simple ： Use Go The language is easy to write and deploy ; Use gRPC Defining interfaces , Support for cross language 、 Cross-platform feature ; The user-friendly Raft The algorithm guarantees consistency , be better than Paxos Algorithm .
• Fast development ：etcd In high-speed iterative development .
• Superior performance ： Official benchmark data ,etcd Clusters can support... Per second 10000+ Second write , Better performance than the Zookeeper.
• Security ：etcd Support TLS visit , and ZooKeeper It is slightly rough in terms of permission control .

Environment building

One 、 Local installation package deployment

「 download 」： Download the latest installation package （ Current latest ：v3.5.4）, Download address ：https://github.com/etcd-io/etcd/releases/

「 install 」： In the unzipped file directory etcd、etcdctl These are the compiled execution files of the installation package and the client , There are three ways to run the configuration .

• Method 1 ： Unzip the directory and run directly
• Method 2 ： hold etcd、 etcdctl File copy to GOBIN Under the table of contents .
• Method 3 ： Add... To the environment variable etcd、 etcdctl Directory of files .

notes ： In operation , Permission issues may be involved , Authorization is enough .

「 verification 」：

#  verification  etcd  edition 
$ etcd --version

etcd Version: 3.5.4
Git SHA: 08407ff76
Go Version: go1.16.15
Go OS/Arch: darwin/amd64

#  verification  etcdctl  edition 
$ etcdctl version

etcdctl version: 3.5.4
API version: 3.5

Two 、 Compile and deploy locally

「 download 」： Use the following command to clone the code

#  Download the latest version 
$ git clone https://github.com/etcd-io/etcd.git
#  Download the specified version 
$ git clone -b v3.5.4 https://github.com/etcd-io/etcd.git

「 Compilation and installation 」：

#  compile 
$ cd etcd
$ make build

#  install 
$ export PATH="$PATH:`pwd`/bin"

「 verification 」：

#  verification  etcd  edition 
$ etcd --version

#  verification  etcdctl  edition 
$ etcdctl version

#  verification  etcdutl  edition 
$ etcdutl version

3、 ... and 、 Local cluster deployment

Installation is required first goreman Components , It's based on Procfile Profile management etcd Application process .

$ go install github.com/mattn/[email protected]

「 Start cluster 」： Source directory Procfile The script has built the local demo cluster , Just run and start directly

$ goreman start

「 verification 」

$ etcdctl member list

8211f1d0f64f3269, started, infra1, http://127.0.0.1:12380, http://127.0.0.1:2379, false
91bc3c398fb3c146, started, infra2, http://127.0.0.1:22380, http://127.0.0.1:22379, false
fd422379fda50e48, started, infra3, http://127.0.0.1:32380, http://127.0.0.1:32379, false

This script creates a script that contains 3 individual etcd Cluster of member nodes , Each cluster member receives read and write of key values . You can also follow Procfile.learner Script guidance , Learn how to add nodes to the cluster .

Four 、Docker Single deployment

Here through docker-compose Carry out the experimental configuration .

「 Mirror pull 」

$ docker pull bitnami/etcd:3.5.2

「 edit docker-compose.yml」

version: '3.5'

services:
  etcd:
    container_name: builder-etcd
    image: bitnami/etcd:3.5.2
    ports:
      - 2379:2379
    environment:
      - ALLOW_NONE_AUTHENTICATION=yes
      - ETCD_AUTO_COMPACTION_MODE=revision
      - ETCD_AUTO_COMPACTION_RETENTION=1002
      - ETCD_QUOTA_BACKEND_BYTES=4294967296
    volumes:
      - ${DOCKER_ROOT_DIR:-.}/volumes/etcd/data:/bitnami/etcd

networks:
  default:
    name: builder_dev

「 Start the service 」

$ docker-compose -f docker-compose.yml up

「 verification 」： Verify the version of the cluster node

$ docker exec -it builder-etcd /bin/bash -c "etcd --version"

etcd Version: 3.5.2
Git SHA: 99018a77b
Go Version: go1.16.3
Go OS/Arch: linux/amd64

5、 ... and 、Docker Cluster deployment

「 edit docker-compose.yml」

version: '3.5'

services:
  etcd1:
    container_name: builder-etcd1
    image: bitnami/etcd:3.5.2
    ports:
      - 12379:2379
    environment:
      - ALLOW_NONE_AUTHENTICATION=yes
      - ETCD_AUTO_COMPACTION_MODE=revision
      - ETCD_AUTO_COMPACTION_RETENTION=1002
      - ETCD_QUOTA_BACKEND_BYTES=4294967296
      - ETCD_NAME=etcd1
      - ETCD_INITIAL_ADVERTISE_PEER_URLS=http://etcd1:2380
      - ETCD_LISTEN_PEER_URLS=http://0.0.0.0:2380
      - ETCD_LISTEN_CLIENT_URLS=http://0.0.0.0:2379
      - ETCD_ADVERTISE_CLIENT_URLS=http://etcd1:2379
      - ETCD_INITIAL_CLUSTER_TOKEN=etcd-cluster
      - ETCD_INITIAL_CLUSTER=etcd1=http://etcd1:2380,etcd2=http://etcd2:2380,etcd3=http://etcd3:2380
      - ETCD_INITIAL_CLUSTER_STATE=new
    volumes:
      - ${DOCKER_ROOT_DIR:-.}/volumes/etcd/data1:/bitnami/etcd

  etcd2:
    container_name: builder-etcd2
    image: bitnami/etcd:3.5.2
    ports:
      - 22379:2379
    environment:
      - ALLOW_NONE_AUTHENTICATION=yes
      - ETCD_AUTO_COMPACTION_MODE=revision
      - ETCD_AUTO_COMPACTION_RETENTION=1002
      - ETCD_QUOTA_BACKEND_BYTES=4294967296
      - ETCD_NAME=etcd2
      - ETCD_INITIAL_ADVERTISE_PEER_URLS=http://etcd2:2380
      - ETCD_LISTEN_PEER_URLS=http://0.0.0.0:2380
      - ETCD_LISTEN_CLIENT_URLS=http://0.0.0.0:2379
      - ETCD_ADVERTISE_CLIENT_URLS=http://etcd2:2379
      - ETCD_INITIAL_CLUSTER_TOKEN=etcd-cluster
      - ETCD_INITIAL_CLUSTER=etcd1=http://etcd1:2380,etcd2=http://etcd2:2380,etcd3=http://etcd3:2380
      - ETCD_INITIAL_CLUSTER_STATE=new
    volumes:
      - ${DOCKER_ROOT_DIR:-.}/volumes/etcd/data2:/bitnami/etcd

  etcd3:
    container_name: builder-etcd3
    image: bitnami/etcd:3.5.2
    ports:
      - 32379:2379
    environment:
      - ALLOW_NONE_AUTHENTICATION=yes
      - ETCD_AUTO_COMPACTION_MODE=revision
      - ETCD_AUTO_COMPACTION_RETENTION=1002
      - ETCD_QUOTA_BACKEND_BYTES=4294967296
      - ETCD_NAME=etcd3
      - ETCD_INITIAL_ADVERTISE_PEER_URLS=http://etcd3:2380
      - ETCD_LISTEN_PEER_URLS=http://0.0.0.0:2380
      - ETCD_LISTEN_CLIENT_URLS=http://0.0.0.0:2379
      - ETCD_ADVERTISE_CLIENT_URLS=http://etcd3:2379
      - ETCD_INITIAL_CLUSTER_TOKEN=etcd-cluster
      - ETCD_INITIAL_CLUSTER=etcd1=http://etcd1:2380,etcd2=http://etcd2:2380,etcd3=http://etcd3:2380
      - ETCD_INITIAL_CLUSTER_STATE=new
    volumes:
      - ${DOCKER_ROOT_DIR:-.}/volumes/etcd/data3:/bitnami/etcd

networks:
  default:
    name: builder_dev

Deployment profile docker-compose.yml details , See etcd docker-compose yml^[4]

「 Start the service 」

$ docker-compose -f docker-compose.yml up

「 verification 」： Verify the version of the cluster node

$ docker exec -it builder-etcd1 /bin/bash -c "etcd --version"
$ docker exec -it builder-etcd2 /bin/bash -c "etcd --version"
$ docker exec -it builder-etcd3 /bin/bash -c "etcd --version"

#  Output 
etcd Version: 3.5.2
Git SHA: 99018a77b
Go Version: go1.16.3
Go OS/Arch: linux/amd64

API Study

here , By using etcdctl^[5] Conduct API Learning verification ,etcdctl It's one used to communicate with etcd Command line tools for server interaction .

「1. View version 」

$ etcdctl version

etcdctl version: 3.6.0-alpha.0
API version: 3.6

「2. write in key」

$ etcdctl put foo bar
OK

「3. Read key」

$ etcdctl get foo
foo
bar
#  Just get value 
$ etcdctl get foo --print-value-only
bar

「4. Batch values 」

$ etcdctl put foo1 bar1
$ etcdctl put foo3 bar2
$ etcdctl put foo3 bar3

#  Get from  foo  To  foo3  Value , barring  foo3
$ etcdctl get foo foo3 --print-value-only 
bar
bar1
bar2

#  Get the prefix  foo  Value 
$ etcdctl get --prefix foo --print-value-only
bar
bar1
bar2
bar3

#  Get the first two values that match the prefix 
$ etcdctl get --prefix --limit=2 foo --print-value-only
bar
bar1

「5. Delete key」

#  Delete  foo  Value 
$ etcdctl del foo
1

#  Delete  foo  To  foo2  And it doesn't include  foo2  Value 
$ etcdctl del foo foo2
1
#  Delete prefix  foo  All values 
$ etcdctl del --prefix foo
2

「6. monitor 」

#  monitor  foo  Single  key
$ etcdctl watch foo
#  Another console performs ： etcdctl put foo bar
PUT
foo
bar

#  Monitor multiple values at the same time 
$ etcdctl watch -i
$ watch foo
$ watch zoo
#  Another console performs : etcdctl put foo bar
PUT
foo
bar

#  Another console performs : etcdctl put zoo val
PUT
zoo
val

#  monitor  foo  Prefix hit  key
$ etcdctl watch --prefix foo
#  Another console performs ： etcdctl put foo1 bar1
PUT
foo1
bar1
#  Another console performs ： etcdctl put fooz1 barz1
PUT
fooz1
barz1

「7. Set up a lease 」 When one key When bound to a lease , Its life cycle is bound to the life cycle of the lease .

#  Set up 10 Expiration time in seconds 
$ etcdctl lease grant 10
lease 32698142c52a170a granted with TTL(10s)

#  hold  foo  Bound to lease , Set to  10  Seconds after expired 
$ etcdctl put --lease=32698142c52a170a foo bar
OK
$ etcdctl get foo
foo
bar

# 10  Seconds later , Can't get  foo
$ etcdctl get foo
#  Returns an empty 

「8. Cancel the lease 」 Through the lease ID Cancel the lease , Revoking a lease will delete all its bound key.

$ etcdctl lease grant 10
lease 32698142c52a170c granted with TTL(10s)
$ etcdctl put --lease=32698142c52a170c foo bar
OK

#  Cancel the lease 
$ etcdctl lease revoke 32698142c52a170c
lease 32698142c52a170c revoked

$ etcdctl get foo
#  Returns an empty 

「9. The contract 」 By refreshing TTL Value to keep the lease valid , Keep it from expiring .

#  Set up  10  The lease expires in seconds 
$ etcdctl lease grant 10
lease 32698142c52a170f granted with TTL(10s)

#  hold  foo  Bound to lease , Set to  10  Seconds after expired 
$ etcdctl put foo bar --lease=32698142c52a170f

#  Automatic scheduled renewal , After the successful renewal, each lease is  10  second 
$ etcdctl lease keep-alive 32698142c52a170f
lease 32695410dcc0ca06 keepalived with TTL(10)
lease 32695410dcc0ca06 keepalived with TTL(10)
lease 32695410dcc0ca06 keepalived with TTL(10)
...

「10. View lease 」 View lease information , To renew the lease or to see if the lease still exists or has expired

#  Set up  50  second  TTL
$ etcdctl lease grant 50
lease 32698142c52a1711 granted with TTL(50s)

# zoo1  binding  32698142c52a1711  lease 
$ etcdctl put --lease=32698142c52a1711 zoo1 val1
OK

#  View lease ,remaining(32s)  Remaining valid time 32 second ;--keys  Get the lease bound  key
$ etcdctl lease timetolive --keys 32698142c52a1711
lease 32698142c52a1711 granted with TTL(50s), remaining(32s), attached keys([zoo1])

notes ： One lease supports binding multiple key

$ etcdctl lease grant 50
lease 32698142c52a1713 granted with TTL(50s)

$ etcdctl put --lease=32698142c52a1713 zoo1 val1
OK

$ etcdctl put --lease=32698142c52a1713 zoo2 val2
OK

$ etcdctl put --lease=32698142c52a1713 zoo3 val3
OK

After the lease expires , all key Values will be deleted , therefore ：

• When the lease is bound to only one key when , Want to delete this key, The best way is to cancel its lease , Instead of deleting this key.
• When the lease is not bound key when , It should be cancelled voluntarily , Simply delete key after , The renewal operation continues , Can cause memory leaks .

#  Method 1 ： Delete directly `key`
#  Set the lease and bind  zoo1
$ etcdctl lease grant 50
lease 32698142c52a1715 granted with TTL(50s)
$ etcdctl --lease=32698142c52a1715 put zoo1 val1
OK

#  The contract 
$ etcdctl lease keep-alive 32698142c52a1715
lease 32698142c52a1715 keepalived with TTL(50)

#  Another console performs ：etcdctl del zoo1
#  Simply delete  key  after , The renewal operation continues , Can cause memory leaks 
lease 32698142c52a1715 keepalived with TTL(50)
lease 32698142c52a1715 keepalived with TTL(50)
lease 32698142c52a1715 keepalived with TTL(50)
...

#  Method 2 ： revoke `key` Lease of 
#  Set the lease and bind  zoo1
$ etcdctl lease grant 50
lease 32698142c52a1717 granted with TTL(50s)
$ etcdctl --lease=32698142c52a1717 put zoo1 val1
OK

#  The contract 
$ etcdctl lease keep-alive 32698142c52a1717
lease 32698142c52a1717 keepalived with TTL(50)
lease 32698142c52a1717 keepalived with TTL(50)

#  Another console performs ：etcdctl lease revoke 32698142c52a1717

#  Renew, cancel and exit 
lease 32698142c52a1717 expired or revoked.
$ etcdctl get zoo1
#  Returns an empty 

above , That's all for today , It almost includes etcd Various postures for installation and use , You are welcome to try .

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References

• [0] Thirty-one : http://www.lee31.cn/assets/image/ThirtyOneLee.jpeg
• [1] etcd: https://github.com/etcd-io/etcd
• [2] etcd The origin of the name : https://etcd.io/docs/v3.5/faq/
• [3] https://www.infoq.cn/article/etcd-interpretation-application-scenario-implement-principle/
• [4] etcd docker-compose yml: https://github.com/liyaodev/docker-compose
• [5] etcdctl: https://etcd.io/docs/v3.5/dev-guide/interacting_v3/

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