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 "%s\n" "$*" 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 "%s\n" "$1"| cut -d : -f 1) port=$(printf "%s\n" "$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 [ "$host" = "" ]; then echoerr "error: you need to provide a host to test." usage 2 fi ;; esac wait_for "$@"
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