使用docker-compose搭建etcd集群环境

使用docker-compose搭建etcd集群环境

etcd是一个集群环境，用来管理微服务架构下面的配置管理功能。
A distributed, reliable key-value store for the most critical data of a distributed system.

这篇文章是一个基础步骤如何搭建etcd的docker集群环境。
我们使用docker-compose来搭建如下的etcd集群环境：

1. 集群包含三个node：etcd1, etcd2, etcd3

1. 下载consul docker image

$ docker pull quay.io/coreos/etcd

2. 编辑docker-compose.yaml文件

$ cat docker-compose.yaml
version: '2'
networks:
  byfn:

services:
  etcd1:
    image: quay.io/coreos/etcd
    container_name: etcd1
    command: etcd -name etcd1 -advertise-client-urls http://0.0.0.0:2379 -listen-client-urls http://0.0.0.0:2379 -listen-peer-urls http://0.0.0.0:2380 -initial-cluster-token etcd-cluster -initial-cluster "etcd1=http://etcd1:2380,etcd2=http://etcd2:2380,etcd3=http://etcd3:2380" -initial-cluster-state new
    ports:
      - 2379
      - 2380
    networks:
      - byfn

  etcd2:
    image: quay.io/coreos/etcd
    container_name: etcd2
    command: etcd -name etcd2 -advertise-client-urls http://0.0.0.0:2379 -listen-client-urls http://0.0.0.0:2379 -listen-peer-urls http://0.0.0.0:2380 -initial-cluster-token etcd-cluster -initial-cluster "etcd1=http://etcd1:2380,etcd2=http://etcd2:2380,etcd3=http://etcd3:2380" -initial-cluster-state new
    ports:
      - 2379
      - 2380
    networks:
      - byfn

  etcd3:
    image: quay.io/coreos/etcd
    container_name: etcd3
    command: etcd -name etcd3 -advertise-client-urls http://0.0.0.0:2379 -listen-client-urls http://0.0.0.0:2379 -listen-peer-urls http://0.0.0.0:2380 -initial-cluster-token etcd-cluster -initial-cluster "etcd1=http://etcd1:2380,etcd2=http://etcd2:2380,etcd3=http://etcd3:2380" -initial-cluster-state new
    ports:
      - 2379
      - 2380
    networks:
      - byfn

3. 启动服务

$ docker-compose up

4. 验证集群的状态

验证从三个node返回的v2/members数据是一样的值。

$ docker ps
CONTAINER ID        IMAGE                 COMMAND                  CREATED             STATUS              PORTS                                              NAMES
33785a959d95        quay.io/coreos/etcd   "etcd -name etcd1 ..."   2 hours ago         Up 2 hours          0.0.0.0:32791->2379/tcp, 0.0.0.0:32790->2380/tcp   etcd1
106ba12b1c25        quay.io/coreos/etcd   "etcd -name etcd2 ..."   2 hours ago         Up 2 hours          0.0.0.0:32789->2379/tcp, 0.0.0.0:32788->2380/tcp   etcd2
76cd127439a3        quay.io/coreos/etcd   "etcd -name etcd3 ..."   2 hours ago         Up 2 hours          0.0.0.0:32787->2379/tcp, 0.0.0.0:32786->2380/tcp   etcd3

$ curl -L http://127.0.0.1:32787/v2/members
{"members":[{"id":"ade526d28b1f92f7","name":"etcd1","peerURLs":["http://etcd1:2380"],"clientURLs":["http://0.0.0.0:2379"]},{"id":"bd388e7810915853","name":"etcd3","peerURLs":["http://etcd3:2380"],"clientURLs":["http://0.0.0.0:2379"]},{"id":"d282ac2ce600c1ce","name":"etcd2","peerURLs":["http://etcd2:2380"],"clientURLs":["http://0.0.0.0:2379"]}]}

$ curl -L http://127.0.0.1:32789/v2/members
{"members":[{"id":"ade526d28b1f92f7","name":"etcd1","peerURLs":["http://etcd1:2380"],"clientURLs":["http://0.0.0.0:2379"]},{"id":"bd388e7810915853","name":"etcd3","peerURLs":["http://etcd3:2380"],"clientURLs":["http://0.0.0.0:2379"]},{"id":"d282ac2ce600c1ce","name":"etcd2","peerURLs":["http://etcd2:2380"],"clientURLs":["http://0.0.0.0:2379"]}]}

$ curl -L http://127.0.0.1:32791/v2/members
{"members":[{"id":"ade526d28b1f92f7","name":"etcd1","peerURLs":["http://etcd1:2380"],"clientURLs":["http://0.0.0.0:2379"]},{"id":"bd388e7810915853","name":"etcd3","peerURLs":["http://etcd3:2380"],"clientURLs":["http://0.0.0.0:2379"]},{"id":"d282ac2ce600c1ce","name":"etcd2","peerURLs":["http://etcd2:2380"],"clientURLs":["http://0.0.0.0:2379"]}]}

也可以用命令行工具etcdctl：

$ docker exec -t etcd1 etcdctl member list
ade526d28b1f92f7: name=etcd1 peerURLs=http://etcd1:2380 clientURLs=http://0.0.0.0:2379 isLeader=false
bd388e7810915853: name=etcd3 peerURLs=http://etcd3:2380 clientURLs=http://0.0.0.0:2379 isLeader=false
d282ac2ce600c1ce: name=etcd2 peerURLs=http://etcd2:2380 clientURLs=http://0.0.0.0:2379 isLeader=true

$ docker exec -t etcd3 etcdctl -C http://etcd1:2379,http://etcd2:2379,http://etcd3:2379 member list
ade526d28b1f92f7: name=etcd1 peerURLs=http://etcd1:2380 clientURLs=http://0.0.0.0:2379 isLeader=false
bd388e7810915853: name=etcd3 peerURLs=http://etcd3:2380 clientURLs=http://0.0.0.0:2379 isLeader=false
d282ac2ce600c1ce: name=etcd2 peerURLs=http://etcd2:2380 clientURLs=http://0.0.0.0:2379 isLeader=true

4. 集群的使用

我们往一个node上上传数据，在其他node上就能下载到。

curl -L http://127.0.0.1:32789/v2/keys/foo -XPUT -d value="Hello foo"
curl -L http://127.0.0.1:32789/v2/keys/foo1/foo1 -XPUT -d value="Hello foo1"
curl -L http://127.0.0.1:32789/v2/keys/foo2/foo2 -XPUT -d value="Hello foo2"
curl -L http://127.0.0.1:32789/v2/keys/foo2/foo21/foo21 -XPUT -d value="Hello foo21"

curl -L http://127.0.0.1:32787/v2/keys/foo
curl -L http://127.0.0.1:32787/v2/keys/foo2
curl -L http://127.0.0.1:32787/v2/keys/foo2?recursive=true

etcd的详细API请参考相关文档。