docker-compose实践

docker-compose实践

• docker-compose.yml一个例子

version: '3'
services:
  web:
    build: .
    ports:
    - "5000:5000"
    volumes:
    - .:/code
    - logvolume01:/var/log
    links:
    - redis
  redis:
    image: redis
volumes:
  logvolume01: {}

安装（linux）

官方安装

• 官方安装方法有时会非常缓慢，暂时不清楚啥原因

• 下载指定版本的docker-compose,注意以下命令的版本号请根据实际情况修改，截止目前为止最新的是1.24.0

  sudo curl -L "https://github.com/docker/compose/releases/download/1.24.0/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
  

• 授予可执行权限

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

• 以上两行基本就算把docker-compose安装好了

• 可以查询版本号看看是否安装成功

  docker-compose --version
  

• 如果发现没有docker-compose命令，检查下docker-compose路径，或者可以在其他目录(比如/usr/bin/docker-compose)创建一个链接指向docker-compose

  sudo ln -s /usr/local/bin/docker-compose /usr/bin/docker-compose
  

非官方安装

• 假如你条件受限无法科学上网，那么只能通过其他路径下载安装docker-compose

• 安装命令如下（ubuntu）

  apt-get update
  apt-get install -y docker-compose
  

• 可以查询版本号看看是否安装成功

  docker-compose --version
  

卸载

• 假如你是通过官方安装，即通过curl下载安装的，那么卸载则直接移除目录即可

  sudo rm /usr/local/bin/docker-compose
  

• 如果是通过其他工具安装，请参照各工具的卸载方法，假如是用pip安装的，则用以下命令卸载

  pip uninstall docker-compose
  

docker-compose.yml

• 官方说明：https://docs.docker.com/compose/compose-file/
• 要使用docker-compose这个工具，则需要我们编写docker-compose.yml文件

  version: "3" #指定版本，不同版本支持的指令不同
  services:
    webapp: # 容器名称，此名称可以用在docker-compose指令上
   	build: ./dir  #构建路径，即dockerfile文件所在目录
    	depends_on: # 依赖的服务，这个决定了启动顺序，但只是保证了容器的启动顺序，并不保证容器内服务的启动顺序
    	 - mysql-server
    	container_name: name # 容器名称，相当于run指令的--name
    	network_mode: host #网络模式，相当于run指令的--net
    	restart: always # 重启模式，相当于run指令的--restart
    	image: hello-world # 使用的镜像名称
    	external_links: #相当于run指令的--link ,不过external_link需要双方都是桥接模式bridge
    		- external-mysql
    	links: #与external_links不同的是这是内部，即在这个docker-compose声明的容器
    		- in-mysql
    	ports: 
    		- "3306:3306" # 端口映射，相当于run指令的-p
    	volumes:
    	 	- /abc/d:/abc/d # 相当于run指令的-v
    	environment: # 相当于run指令的-e
    	 - TZ=Asia/Shanghai        #这里设置容器的时区为亚洲上海，也就解决了容器通过compose编排启动的时区问题！！！！解决了容器的时区问题！！！
    	 - ENV_1=param1
    	 - ENV_2=param2
    	command:  cmd #启动时执行的命令
    	mem_limit: 400M #限制容器使用内存,相当于run --memory
    	memswap_limit: 1G #限制swap大小,相当于run --memory-swap
    	deploy: 
        replicas: 6 #服务实例个数
    mysql:
    	container_name: in-mysql
    	image: mysql
      
      
  
  

• 如果同时存在build和image,则以image的内容作为镜像的名称，然后开始构建并启动服务

更新

• 我们的docker-compose.yml肯定不是一层不变的，有时会有一些参数的变化

• 默认支持的是docker-compose.override.yml,也是就说当你在执行 docker-compose up 时，docker-compose.override.yml的内容会覆盖到docker-compose.yml

• 当然如果你要覆盖的文件名不是docker-compose.override.yml，那么就要在up时指定，比如为docker-compose.prod.yml

  docker-compose -f docker-compose.yml -f docker-compose.prod.yml up -d
  

• 当你应用程序的代码发送变化时,应当重新构建镜像和运行容器，比如重新部署一个叫web的服务

  docker-compose build web
  docker-compose up --no-deps -d web
  

• –no deps标志防止compose同时重新创建Web依赖的任何服务

启动顺序

• 很遗憾，docker-compose本身并没有对服务启动顺序的支持，但很多时候我们的服务之间是需要启动顺序的

• 对此，docker官方文档中有提到三个工具，原文在这里 https://docs.docker.com/compose/startup-order/

  • wait-for-it
  • dockerize
  • wait-for

• 此处以wait-for-it为例， war-for-it的用法很简单，就是把wait-for-it.sh下载下来，赋予可执行权限

• 详细用法如下

  wait-for-it.sh host:port [-s] [-t timeout] [-- command args]
  -h HOST | --host=HOST       Host or IP under test
  -p PORT | --port=PORT       TCP port under test
                              Alternatively, you specify the host and port as host:port
  -s | --strict               Only execute subcommand if the test succeeds
  -q | --quiet                Don't output any status messages
  -t TIMEOUT | --timeout=TIMEOUT
                              Timeout in seconds, zero for no timeout
  -- COMMAND ARGS             Execute command with args after the test finishes
  

• 例如

  guest@ubuntu16-cn:~/hwj/test$ ./wait-for-it.sh www.baidu.com:80 -- echo "hello"
  wait-for-it.sh: waiting 15 seconds for www.baidu.com:80
  wait-for-it.sh: www.baidu.com:80 is available after 0 seconds
  hello
  

• docker-compose.yml中假如需要等待db启动后才启动web,则如下示例

  version: "2"
  services:
    web:
      build: .
      ports:
        - "80:8000"
      depends_on:
        - "db"
      command: ["./wait-for-it.sh", "db:5432", "--", "python", "app.py"]
    db:
      image: postgres
  

• 以下就是从github摘抄过来的 wait-for-it.sh

  #!/usr/bin/env bash
  #   Use this script to test if a given TCP host/port are available
  
  WAITFORIT_cmdname=${0##*/}
  
  echoerr() { if [[ $WAITFORIT_QUIET -ne 1 ]]; then echo "$@" 1>&2; fi }
  
  usage()
  {
      cat << USAGE >&2
  Usage:
      $WAITFORIT_cmdname host:port [-s] [-t timeout] [-- command args]
      -h HOST | --host=HOST       Host or IP under test
      -p PORT | --port=PORT       TCP port under test
                                  Alternatively, you specify the host and port as host:port
      -s | --strict               Only execute subcommand if the test succeeds
      -q | --quiet                Don't output any status messages
      -t TIMEOUT | --timeout=TIMEOUT
                                  Timeout in seconds, zero for no timeout
      -- COMMAND ARGS             Execute command with args after the test finishes
  USAGE
      exit 1
  }
  
  wait_for()
  {
      if [[ $WAITFORIT_TIMEOUT -gt 0 ]]; then
          echoerr "$WAITFORIT_cmdname: waiting $WAITFORIT_TIMEOUT seconds for $WAITFORIT_HOST:$WAITFORIT_PORT"
      else
          echoerr "$WAITFORIT_cmdname: waiting for $WAITFORIT_HOST:$WAITFORIT_PORT without a timeout"
      fi
      WAITFORIT_start_ts=$(date +%s)
      while :
      do
          if [[ $WAITFORIT_ISBUSY -eq 1 ]]; then
              nc -z $WAITFORIT_HOST $WAITFORIT_PORT
              WAITFORIT_result=$?
          else
              (echo > /dev/tcp/$WAITFORIT_HOST/$WAITFORIT_PORT) >/dev/null 2>&1
              WAITFORIT_result=$?
          fi
          if [[ $WAITFORIT_result -eq 0 ]]; then
              WAITFORIT_end_ts=$(date +%s)
              echoerr "$WAITFORIT_cmdname: $WAITFORIT_HOST:$WAITFORIT_PORT is available after $((WAITFORIT_end_ts - WAITFORIT_start_ts)) seconds"
              break
          fi
          sleep 1
      done
      return $WAITFORIT_result
  }
  
  wait_for_wrapper()
  {
      # In order to support SIGINT during timeout: http://unix.stackexchange.com/a/57692
      if [[ $WAITFORIT_QUIET -eq 1 ]]; then
          timeout $WAITFORIT_BUSYTIMEFLAG $WAITFORIT_TIMEOUT $0 --quiet --child --host=$WAITFORIT_HOST --port=$WAITFORIT_PORT --timeout=$WAITFORIT_TIMEOUT &
      else
          timeout $WAITFORIT_BUSYTIMEFLAG $WAITFORIT_TIMEOUT $0 --child --host=$WAITFORIT_HOST --port=$WAITFORIT_PORT --timeout=$WAITFORIT_TIMEOUT &
      fi
      WAITFORIT_PID=$!
      trap "kill -INT -$WAITFORIT_PID" INT
      wait $WAITFORIT_PID
      WAITFORIT_RESULT=$?
      if [[ $WAITFORIT_RESULT -ne 0 ]]; then
          echoerr "$WAITFORIT_cmdname: timeout occurred after waiting $WAITFORIT_TIMEOUT seconds for $WAITFORIT_HOST:$WAITFORIT_PORT"
      fi
      return $WAITFORIT_RESULT
  }
  
  # process arguments
  while [[ $# -gt 0 ]]
  do
      case "$1" in
          *:* )
          WAITFORIT_hostport=(${1//:/ })
          WAITFORIT_HOST=${WAITFORIT_hostport[0]}
          WAITFORIT_PORT=${WAITFORIT_hostport[1]}
          shift 1
          ;;
          --child)
          WAITFORIT_CHILD=1
          shift 1
          ;;
          -q | --quiet)
          WAITFORIT_QUIET=1
          shift 1
          ;;
          -s | --strict)
          WAITFORIT_STRICT=1
          shift 1
          ;;
          -h)
          WAITFORIT_HOST="$2"
          if [[ $WAITFORIT_HOST == "" ]]; then break; fi
          shift 2
          ;;
          --host=*)
          WAITFORIT_HOST="${1#*=}"
          shift 1
          ;;
          -p)
          WAITFORIT_PORT="$2"
          if [[ $WAITFORIT_PORT == "" ]]; then break; fi
          shift 2
          ;;
          --port=*)
          WAITFORIT_PORT="${1#*=}"
          shift 1
          ;;
          -t)
          WAITFORIT_TIMEOUT="$2"
          if [[ $WAITFORIT_TIMEOUT == "" ]]; then break; fi
          shift 2
          ;;
          --timeout=*)
          WAITFORIT_TIMEOUT="${1#*=}"
          shift 1
          ;;
          --)
          shift
          WAITFORIT_CLI=("$@")
          break
          ;;
          --help)
          usage
          ;;
          *)
          echoerr "Unknown argument: $1"
          usage
          ;;
      esac
  done
  
  if [[ "$WAITFORIT_HOST" == "" || "$WAITFORIT_PORT" == "" ]]; then
      echoerr "Error: you need to provide a host and port to test."
      usage
  fi
  
  WAITFORIT_TIMEOUT=${WAITFORIT_TIMEOUT:-15}
  WAITFORIT_STRICT=${WAITFORIT_STRICT:-0}
  WAITFORIT_CHILD=${WAITFORIT_CHILD:-0}
  WAITFORIT_QUIET=${WAITFORIT_QUIET:-0}
  
  # check to see if timeout is from busybox?
  WAITFORIT_TIMEOUT_PATH=$(type -p timeout)
  WAITFORIT_TIMEOUT_PATH=$(realpath $WAITFORIT_TIMEOUT_PATH 2>/dev/null || readlink -f $WAITFORIT_TIMEOUT_PATH)
  if [[ $WAITFORIT_TIMEOUT_PATH =~ "busybox" ]]; then
          WAITFORIT_ISBUSY=1
          WAITFORIT_BUSYTIMEFLAG="-t"
  
  else
          WAITFORIT_ISBUSY=0
          WAITFORIT_BUSYTIMEFLAG=""
  fi
  
  if [[ $WAITFORIT_CHILD -gt 0 ]]; then
      wait_for
      WAITFORIT_RESULT=$?
      exit $WAITFORIT_RESULT
  else
      if [[ $WAITFORIT_TIMEOUT -gt 0 ]]; then
          wait_for_wrapper
          WAITFORIT_RESULT=$?
      else
          wait_for
          WAITFORIT_RESULT=$?
      fi
  fi
  
  if [[ $WAITFORIT_CLI != "" ]]; then
      if [[ $WAITFORIT_RESULT -ne 0 && $WAITFORIT_STRICT -eq 1 ]]; then
          echoerr "$WAITFORIT_cmdname: strict mode, refusing to execute subprocess"
          exit $WAITFORIT_RESULT
      fi
      exec "${WAITFORIT_CLI[@]}"
  else
      exit $WAITFORIT_RESULT
  fi
  

vishnubob/wait-for-it: Pure bash script to test and wait on the availability of a TCP host and port
https://github.com/vishnubob/wait-for-it

指令

• docker-compose的指令说明：https://docs.docker.com/compose/reference/
• 也可以通过docker-compose --help获得指令帮助说明
• 以下是最常用的指令

  doceker-compose -f customname.yml up  # 自定义yml文件名，默认都是docker-compose.yml名称
  doceker-compose up -d # 表示后台启动
  docker-compose restart # 重启
  docker-compose stop #停止服务
  docker-compose down # 停止服务并删除镜像
  docker-compose down --volumes # 停止服务，删除镜像并删除数据卷
  docker-compose ps # 查看当前正在跑的服务
  

参考

(1条消息)我的docker随笔5：docker-compose的安装与使用 - 李迟的专栏 - CSDN博客
https://blog.csdn.net/subfate/article/details/80905985

Compose file version 3 reference | Docker Documentation
https://docs.docker.com/compose/compose-file/
docker-compose命令 - 坚强的小蚂蚁 - 博客园
https://www.cnblogs.com/regit/p/8309959.html
docker compose 服务启动顺序控制 - wang_yb - 博客园
https://www.cnblogs.com/wang_yb/p/9400291.html

docker-compose命令 - 坚强的小蚂蚁 - 博客园
https://www.cnblogs.com/regit/p/8309959.html