浅谈Docker-compose中的depends_on顺序的问题解决

使用depends_on进行容器排序时并不能完美的解决容器之间的依赖问题，原因是因为 depends_on只能保证容器进入到 运行状态而不是完全状态（不知道怎么描述了）。

网上已经列出来了解决方法，使用 wait-for-it或者 wait-for，在启动时对需要优先启动的容器进行访问，当可以访问成功时在启动，但是都不够详细，甚至很多都是同样的内容，（这里吐槽一下环境真乱）。

可能我比较笨，花了一天才解决，在这里记录下来。

我使用的是 wait-for ，wait-for-it.sh我测试的时候了出现了保错所以没用。

正文：

需求是要将一个 打包好的 ar文件注册到nacos中，但是nacos启动较慢，就需要进行顺序的设置。

将需要的 jar文件删除到虚拟机或服务器。接下来编写 dockerfile和docker-compose

FROM openjdk:8-jre // 基于 openjdk COPY wait-for . // 将 wait-for 拷贝到虚拟机中 RUN apt-get update // 更新源， RUN apt-get install netcat -y // 安装 netcat， wait-for 需要使用到 WORKDIR /app // 设置落脚点 ADD course.jar course.jar // 将 jar 文件 添加到 虚拟机中 EXPOSE 8002 // 需要暴露的端口

我的配置是以图片为准的，代码块中的是为了更好的理解 ，想来应该没有差别。

docker-compose

version: 3.0 services: nacos: image: nacos/nacos-server:1.1.4 container_name: nacos ports: – “8848:8848” environment: MODE: standalone # nacos 单节点运行 course: build: /root/ container_name: course ports: – “18002:18002” depends_on: – nacos command: [“sh”,”wait-for”,”nacos:8848″,”–“,”java”,”-jar”,”course.jar”]

这里就不做过多的解释了，与平常相差不大。

我之前查找到的帖子中，没有贴出dockerfile文件在这里最重要的就是，将 wait-for文件拷贝到虚拟机中，因为在 docker-compose中配置的command所使用的 文件是容器中的，如果你没有拷贝那么将找不到文件。然后是 apt-get update和 apt-get install netcat -y则是安装 wait-for运行的环境

我的wait-for代码，26行为超时时间，刚开始是15，但是时间太短了 容器超时我就设置为了 60，这是我唯一跟原来不一样的地方,之后就可以测试运行了

#!/bin/sh # The MIT License (MIT) # # Copyright (c) 2017 Eficode Oy # # Permission is hereby granted, free of charge, to any person obtaining a copy # of this software and associated documentation files (the “Software”), to deal # in the Software without restriction, including without limitation the rights # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell # copies of the Software, and to permit persons to whom the Software is # furnished to do so, subject to the following conditions: # # The above copyright notice and this permission notice shall be included in all # copies or substantial portions of the Software. # # THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE # SOFTWARE. set — “$@” — “$TIMEOUT” “$QUIET” “$PROTOCOL” “$HOST” “$PORT” “$result” TIMEOUT=60 QUIET=0 # The protocol to make the request with, either “tcp” or “http” PROTOCOL=”tcp” echoerr() { if [ “$QUIET” -ne 1 ]; then printf “%sn” “$*” 1>&2; fi } usage() { exitcode=”$1″ cat << USAGE >&2 Usage: $0 host:port|url [-t timeout] [– command args] -q | –quiet Do not output any status messages -t TIMEOUT | –timeout=timeout Timeout in seconds, zero for no timeout — COMMAND ARGS Execute command with args after the test finishes USAGE exit “$exitcode” } wait_for() { case “$PROTOCOL” in tcp) if ! command -v nc >/dev/null; then echoerr nc command is missing! exit 1 fi ;; wget) if ! command -v wget >/dev/null; then echoerr wget command is missing! exit 1 fi ;; esac while :; do case “$PROTOCOL” in tcp) nc -w 1 -z “$HOST” “$PORT” > /dev/null 2>&1 ;; http) wget –timeout=1 -q “$HOST” -O /dev/null > /dev/null 2>&1 ;; *) echoerr “Unknown protocol $PROTOCOL” exit 1 ;; esac result=$? if [ $result -eq 0 ] ; then if [ $# -gt 7 ] ; then for result in $(seq $(($# – 7))); do result=$1 shift set — “$@” “$result” done TIMEOUT=$2 QUIET=$3 PROTOCOL=$4 HOST=$5 PORT=$6 result=$7 shift 7 exec “$@” fi exit 0 fi if [ “$TIMEOUT” -le 0 ]; then break fi TIMEOUT=$((TIMEOUT – 1)) sleep 1 done echo “Operation timed out” >&2 exit 1 } while :; do case “$1″ in http://*|https://*) HOST=”$1″ PROTOCOL=”http” shift 1 ;; *:* ) HOST=$(printf “%sn” “$1″| cut -d : -f 1) PORT=$(printf “%sn” “$1″| cut -d : -f 2) shift 1 ;; -q | –quiet) QUIET=1 shift 1 ;; -q-*) QUIET=0 echoerr “Unknown option: $1” usage 1 ;; -q*) QUIET=1 result=$1 shift 1 set — -“${result#-q}” “$@” ;; -t | –timeout) TIMEOUT=”$2″ shift 2 ;; -t*) TIMEOUT=”${1#-t}” shift 1 ;; –timeout=*) TIMEOUT=”${1#*=}” shift 1 ;; –) shift break ;; –help) usage 0 ;; -*) QUIET=0 echoerr “Unknown option: $1” usage 1 ;; *) QUIET=0 echoerr “Unknown argument: $1” usage 1 ;; esac done if ! [ “$TIMEOUT” -ge 0 ] 2>/dev/null; then echoerr “Error: invalid timeout $TIMEOUT” usage 3 fi case “$PROTOCOL” in tcp) if [ “$HOST” = “” ] || [ “$PORT” = “” ]; then echoerr “Error: you need to provide a host and port to test.” usage 2 fi ;; http) if [ “$HOST” = “” ]; then echoerr “Error: you need to provide a host to test.” usage 2 fi ;; esac wait_for “$@”