Docker Compose入门

发表于 2021-07-31 更新于 2022-04-16 分类于容器化， Cloud Native

Docker Compose入门

简介

一般一个宿主机中会生成多个容器，容器与容器之间需要协调工作，有时多个容器之间也需要进行环境的隔离，而Docker Compose就是用来定义和运行多个容器的工具。可以通过一个yaml文件来配置应用程序的服务，并通过命令来管理所有服务的生命周期。

安装步骤

一般可以在Compose repository release page on GitHub获取到最新版的Docker Compse。

下载

执行以下命令：

1	sudo curl -L "https://github.com/docker/compose/releases/download/1.29.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose

如果需要其他版本的Docker Compse，只需要把命令中的1.29.2替换成需要的版本即可。

如果curl安装有问题，可以参照Alternative Install Options 进行安装。

赋予执行权限

1	sudo chmod +x /usr/local/bin/docker-compose

检查是否安装成功

1 2	> docker-compose --version docker-compose version 1.29.2, build 5becea4c

如何使用

基本配置

在docker compose下，存在服务的概念，一个compose配置可以由多个服务来组成，参考如下yaml配置：

version: "3.9"
services:
  db_mysql:
    image: mysql
    restart: always
    container_name: my-mysql
    ports:
      - 10001:3306
    environment:
      MYSQL_ROOT_PASSWORD: new_password_xxx
    command: 
      --default-authentication-plugin=mysql_native_password
      --character-set-server=utf8mb4
      --collation-server=utf8mb4_unicode_ci
    volumes: 
      - /usr/local/docker/mysql/data/:/var/lib/mysql
      - /usr/local/docker/mysql/conf.d:/etc/mysql/conf.d
  
  redis: 
    image: redis
    hostname: redis-server
    restart: always
    container_name: my-redis
    ports:
      - 10002:6379
    command: redis-server /etc/redis/redis.conf --appendonly yes
    volumes: 
      - /usr/local/docker/redis/conf/redis.conf:/etc/redis/redis.conf
  
  nginx:
    image: nginx
    restart: always
    container_name: my-nginx
    ports:
      - 80:80
    volumes: 
      - /usr/local/docker/nginx/nginx.conf:/etc/nginx/nginx.conf
      
  redis-commander:
    container_name: redis-commander
    hostname: redis-commander
    image: rediscommander/redis-commander:latest
    restart: always
    environment:
      - REDIS_HOSTS=local:redis-server:6379
    ports:
      - 11002:8081

存在一个services节点，该节点下定义了三个服务。每个服务会对应到一个镜像，当执行docker-compose up之后，会根据每个服务对应的镜像，生成对应的容器。服务的名称可以自行定义，无强制要求。

在yaml所在目录下执行

> docker-compose up -d
Creating network "docker-compose_default" with the default driver
Creating my-mysql ... done
Creating my-nginx ... done
Creating my-redis ... done

up为创建并启动所有容器，-d表示守护态运行。这里不指定配置文件名称，则默认当前目录下的名为docker-compose.yml的文件。不指定项目名称，则默认该配置文件所在的目录名称作为项目名称。

可以看到配置文件所定义的所有服务均正常启动。

> docker ps
CONTAINER ID   IMAGE     COMMAND                  CREATED         STATUS         PORTS                                                    NAMES
ea6c7d60903d   redis     "docker-entrypoint.s…"   2 minutes ago   Up 2 minutes   0.0.0.0:10002->6379/tcp, :::10002->6379/tcp              my-redis
49062f5891e7   nginx     "/docker-entrypoint.…"   2 minutes ago   Up 2 minutes   0.0.0.0:80->80/tcp, :::80->80/tcp                        my-nginx
d63a6ed103f5   mysql     "docker-entrypoint.s…"   2 minutes ago   Up 2 minutes   33060/tcp, 0.0.0.0:10001->3306/tcp, :::10001->3306/tcp   my-mysql

常用命令

对于docker-compose有如下选项。

Commands:
  build              Build or rebuild services
  config             Validate and view the Compose file
  create             Create services
  down               Stop and remove resources
  events             Receive real time events from containers
  exec               Execute a command in a running container
  help               Get help on a command
  images             List images
  kill               Kill containers
  logs               View output from containers
  pause              Pause services
  port               Print the public port for a port binding
  ps                 List containers
  pull               Pull service images
  push               Push service images
  restart            Restart services
  rm                 Remove stopped containers
  run                Run a one-off command
  scale              Set number of containers for a service
  start              Start services
  stop               Stop services
  top                Display the running processes
  unpause            Unpause services
  up                 Create and start containers
  version            Show version information and quit

讲一些比较常用的。

up命令，用于创建并启动compose项目。

然后就是start、stop等，仅进行启动和停止服务。

如果是执行down命令，在停止所有服务容器的同时，也会删除所有容器以及网络。

如果改变了一个服务的Dockerfile或者构建目录的内容，可以使用build命令对其进行重建。

ps的用法都差不多，查看所有正在运行的容器。

每个命令具体用法，还是要参见--help。

容器与容器间的访问

一般创建容器

当docker创建一个容器时，会将它纳入一个网络。如果是单独创建容器，则会纳入默认的bridge网络中（默认为bridge模式），如：

新建一个tomcat容器：

1 2	> docker pull tomcat > docker run --name my-tomcat --rm -p 8080:8080 -d tomcat

通过dockers network命令查看

> docker network ls
NETWORK ID     NAME                     DRIVER    SCOPE
3d18fe44fe65   bridge                   bridge    local
de7157fb3e93   docker-compose_default   bridge    local
da3cd2189967   host                     host      local
098d7dd513d5   none                     null      local

可以看到，有一个name为brideg的网络，查看详细信息：

> docker network inspect bridge
[
    {
        "Name": "bridge",
        "Id": "3d18fe44fe65f8d4f370adc558ce41a92897ce58288fa2f16aa2787dcebd9e0c",
        "Created": "2021-07-11T17:04:49.64883344+08:00",
        "Scope": "local",
        "Driver": "bridge",
        "EnableIPv6": false,
        "IPAM": {
            "Driver": "default",
            "Options": null,
            "Config": [
                {
                    "Subnet": "172.17.0.0/16",
                    "Gateway": "172.17.0.1"
                }
            ]
        },
        "Internal": false,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {
            "e42b6c1b108d756cc266cb29d0f6d779c396d62fbc5eef556ad42356ec275b9e": {
                "Name": "my-tomcat",
                "EndpointID": "00e0c410554cb08d4c4c65861d844fc98297f32ca9be628087c934f44bccb82b",
                "MacAddress": "02:42:ac:11:00:02",
                "IPv4Address": "172.17.0.2/16",
                "IPv6Address": ""
            }
        },
        "Options": {
            "com.docker.network.bridge.default_bridge": "true",
            "com.docker.network.bridge.enable_icc": "true",
            "com.docker.network.bridge.enable_ip_masquerade": "true",
            "com.docker.network.bridge.host_binding_ipv4": "0.0.0.0",
            "com.docker.network.bridge.name": "docker0",
            "com.docker.network.driver.mtu": "1500"
        },
        "Labels": {}
    }
]

其中Containers有刚刚创建的my-tomcat容器。

docker-compose创建的网络

在使用docker-compose创建一个项目后，会将该项目中所有的服务(services)都纳入到同一个网络当中，默认的网络名称为项目名加上_default，如上面的docker-compose_default网络。

> docker network inspect docker-compose_default
[
    {
        "Name": "docker-compose_default",
        "Id": "de7157fb3e937908299c17cd3d21380a5dca2960a93bcb9da0ed392f5a4d74d7",
        "Created": "2021-08-01T10:46:49.281728229+08:00",
        "Scope": "local",
        "Driver": "bridge",
        "EnableIPv6": false,
        "IPAM": {
            "Driver": "default",
            "Options": null,
            "Config": [
                {
                    "Subnet": "172.19.0.0/16",
                    "Gateway": "172.19.0.1"
                }
            ]
        },
        "Internal": false,
        "Attachable": true,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {
            "49062f5891e7d12eccbefb19875bcc0bd16b8e79906abb4952bb0420c1d09d72": {
                "Name": "my-nginx",
                "EndpointID": "c3e9773c7cb20222762f37784a24d35912e48edaf332408f61c6be19033382c2",
                "MacAddress": "02:42:ac:13:00:04",
                "IPv4Address": "172.19.0.4/16",
                "IPv6Address": ""
            },
            "d63a6ed103f525148402f57919648e2e7caadd43d51a36597b058a7ecfedf8e4": {
                "Name": "my-mysql",
                "EndpointID": "391283e8835fa8107c6eb95ef946ffabaff8daa9ac5f6325274224f40925cead",
                "MacAddress": "02:42:ac:13:00:03",
                "IPv4Address": "172.19.0.3/16",
                "IPv6Address": ""
            },
            "ea6c7d60903ded82d4c26d5fa47cdcdb005eba94ff5ff825e65e3815e44aab88": {
                "Name": "my-redis",
                "EndpointID": "1dc8f641e6599117fbc9ba605a0940ed1f71b630646db2553670d64fd361d853",
                "MacAddress": "02:42:ac:13:00:02",
                "IPv4Address": "172.19.0.2/16",
                "IPv6Address": ""
            }
        },
        "Options": {},
        "Labels": {
            "com.docker.compose.network": "default",
            "com.docker.compose.project": "docker-compose",
            "com.docker.compose.version": "1.29.2"
        }
    }
]

其中包含了我们创建的三个服务容器。

容器与容器间需要进行网络通信，使用的是CONTAINER_IP:CONTAINER_PORT，而不是映射到宿主机的ip和端口。

举个例子，新加入一个服务到上面的docker-compose.yml中。

version: 3.9
services:
# 省略之前的内容
  redis-commander:
    container_name: redis-commander
    hostname: redis-commander
    image: rediscommander/redis-commander:latest
    restart: always
    environment:
      - REDIS_HOSTS=local:redis:6379
    ports:
      - 11002:8081

environment需要配置redis容器的地址，这里使用local:redis:6379，其中的redis为compose中定义的服务名，通过服务名，docker可以自己获取该服务的当前ip。端口使用的是6379，而非映射的10002。

保存yml后，重新执行docker-compose up -d，会更新有变化的容器。

> docker-compose up -d
Pulling redis-commander (rediscommander/redis-commander:latest)...
latest: Pulling from rediscommander/redis-commander
339de151aab4: Pull complete
f732fa32fc61: Pull complete
ef60bb667d5a: Pull complete
4f50fa5032a4: Pull complete
Digest: sha256:19cd0c49f418779fa2822a0496c5e6516d0c792effc39ed20089e6268477e40a
Status: Downloaded newer image for rediscommander/redis-commander:latest
my-redis is up-to-date
my-nginx is up-to-date
Creating redis-commander ... 
Creating redis-commander ... done

访问11002端口，可以看到redis-commander已成功部署，并正常连接到了我们所配置的redis服务。