Docker学习（七）：Docker-compose-wait-for-it.sh脚本

Docker-compose-使用wait-for-it.sh脚本

1. 微服务编排：nacos+redis+mysql+微服务

编写微服务Dockerfile

生成镜像

# 基础镜像使用java
FROM java:8
# 作者
MAINTAINER hsp
# VOLUME 指定临时文件目录为/tmp，在主机/var/lib/docker目录下创建了一个临时文件并链接到容器的/tmp
VOLUME /tmp
# 将jar包添加到容器中并更名为rb_ms_docker.jar
ADD user-service-1.0-SNAPSHOT.jar user_ms_docker.jar
# 运行jar包
RUN bash -c 'touch /user_ms_docker.jar'
ENTRYPOINT ["java","- jar","/user_ms_docker.jar"]
#暴露6088端口作为微服务
EXPOSE 6062

编写docker-compose.yml文件，自定义网络

服务：nacos+redis+mysql+微服务

version: "3"
services:
  user-Service:
    image: userms:1.0
    container_name: userms
    ports:
      - "6066:6062"
    volumes:
      - /app/userMsDocker/tmp:/tmp
    networks: 
      - hsp_net 
    depends_on: 
      - redis
      - mysql
      - nacos
  redis:
    image: redis
    ports:
      - "6381:6379"
    volumes:
      - /app/redis/data:/data
    networks: 
      - hsp_net
    command: --appendonly yes
  nacos:
    image: nacos/nacos-server
    environment:
      MODE: 'standalone'
    ports:
      - "8849:8848"
    networks: 
      - hsp_net
  mysql:
    image: mysql:5.7
    environment:
      MYSQL_ROOT_PASSWORD: 'root'
    ports:
       - "3307:3306"
    volumes:
       - /app/mysql/master/log:/var/log/mysql
       - /app/mysql/master/data:/var/lib/mysql
       - /app/mysql/master/conf:/etc/mysql/conf.d
    networks:
      - hsp_net
networks: 
   hsp_net: 

2. 遇到问题

nacos、mysql、redis都能正常启动，但是自己的微服务项目容器实例启动了一会就自动停止。

排查后发现是微服务连接nacos异常，连接拒绝

通过查资料与大概猜测是微服务启动时，nacos服务还在启动过程或者还未启动，虽然查看容器实例是启动了，服务可能还未启动

docker compose能够编排容器实例的启动顺序，但是容器里的服务启动快慢之分，无法编排服务的启动顺序

nacos服务本身较大较复杂，启动较慢；我自己编写的微服务用于测试较小且简单，启动快，所以微服务启动时连接nacos异常

3.问题解决

使用wait-for-it.sh脚本

编写微服务Dockerfile,加入脚本文件

# 基础镜像使用java
FROM java:8
# 作者
MAINTAINER hsp
# VOLUME 指定临时文件目录为/tmp，在主机/var/lib/docker目录下创建了一个临时文件并链接到容器的/tmp
VOLUME /tmp
# 将jar包添加到容器中并更名为rb_ms_docker.jar
ADD user-service-1.0-SNAPSHOT.jar user_ms_docker.jar
#ADD wait-for-it脚本
ADD wait-for-it.sh /wait-for-it.sh
# 运行jar包
RUN bash -c 'touch /user_ms_docker.jar'
CMD java -jar /user_ms_docker.jar
#暴露6088端口作为微服务
EXPOSE 6062

重新编写docker-compose文件

services:
  user-Service:
    image: userms:5.0
    container_name: userms
    ports:
      - "6066:6062"
    volumes:
      - /app/userMsDocker/tmp:/tmp
    networks: 
      - hsp_net
    command: ./wait-for-it.sh nacos:8848 -t 0 -- java -jar /user_ms_docker.jar
    depends_on: 
      - redis
      - mysql
      - nacos
  redis:
    image: redis
    ports:
      - "6381:6379"
    volumes:
      - /app/redis/data:/data
    networks: 
      - hsp_net
    command: --appendonly yes
  nacos:
    image: nacos/nacos-server
    environment:
      MODE: 'standalone'
    ports:
      - "8849:8848"
    networks: 
      - hsp_net
  mysql:
    image: mysql:5.7
    environment:
      MYSQL_ROOT_PASSWORD: 'root'
    ports:
       - "3307:3306"
    volumes:
       - /app/mysql/master/log:/var/log/mysql
       - /app/mysql/master/data:/var/lib/mysql
       - /app/mysql/master/conf:/etc/mysql/conf.d
    networks:
      - hsp_net
networks: 
   hsp_net: 

脚本使用

#wait-for-it.sh ip:端口 检测该ip与端口是否已经能连接，能了就执行后面的命令
#-t 0 超时参数 检测该ip与端口是否已经能连接，超过指定时间后管ip与端口是否已经能连接执行后续命令 
#-t 0 不设置超时参数  ip与端口不能连接就不执行后续命令
#不加 -t 0 或者 -t 超时时间 都会在超时时间过了之后执行后续命令 不管ip与端口是否已经能连接
#默认超时时间 15秒
./wait-for-it.sh nacos:8848 -t 0 -- java -jar /user_ms_docker.jar

脚本测试

nacos服务关闭，脚本命令启动微服务

#不加超时参数
./wait-for-it.sh nacos:8848  -- java -jar /user_ms_docker.jar
#显示等15s 之后启动后续命令 nacos服务不存在 微服务启动失败
wait-for-it.sh: waiting 15 seconds for nacos:8848
#不设置超时参数  ip与端口不能连接就不执行后续命令
wait-for-it.sh: waiting for nacos:8848 without a timeout
#显示等待nacos服务启动  nacos服务启动后才可以启动后续命令 一直阻塞等待
wait-for-it.sh: waiting for nacos:8848 without a timeout
#重启nacos后 执行后续命令
wait-for-it.sh: nacos:8848 is available after 123 seconds

3. wait-for-it.sh脚本

可以官网下载

#!/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 -n > /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)

WAITFORIT_BUSYTIMEFLAG=""
if [[ $WAITFORIT_TIMEOUT_PATH =~ "busybox" ]]; then
    WAITFORIT_ISBUSY=1
    # Check if busybox timeout uses -t flag
    # (recent Alpine versions don't support -t anymore)
    if timeout &>/dev/stdout | grep -q -e '-t '; then
        WAITFORIT_BUSYTIMEFLAG="-t"
    fi
else
    WAITFORIT_ISBUSY=0
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