Docker Compose 入门 (二)（docker compose -f）-技术教程-四时宝库

Docker Compose 启动顺序#

docker compose可以同时部署多个服务，但是有时候服务是相互依赖的，比如你的web service需要依赖mysql，所以只有当mysql 服务启动好之后才能启动你的web service，此时我们就需要控制docker compose 配置文件中服务的启动顺序。

创建项目#

创建项目，这里使用spring-boot创建一个mysql的读写应用，该应用依赖mysql服务，所以我们的应用包括两个部分

一个是后台服务由spring boot 编写，另外一个是mysql提供数据库服务。具体spring boot mysql

目录结构如下: 奇技淫巧 find . -maxdepth 2 | sed -e "s/[^-][^\/]*\// |/g" -e "s/|\([^ ]\)/|-\1/"

 |-docker                         //构建docker依赖的文件夹
 | |-init_db.sql                  //为了延长数据库启动时间，我们在启动时执行创建脚本
 | |-wait.sh                      //延时脚本，等待mysql启动
 |-mvnw.cmd
 |-Dockerfile                     //Dockerfile 编译web service的配置文件
 |-pom.xml
 |-docker-compose.yml             //docker compose配置文件
 |-src
 | |-test
 | |-main

编写shell 脚本#

shell 脚本循环ping mysql 服务端口，直到mysql 启动，然后启动web服务

#!/bin/bash

echo "Waiting for mysql"
echo "$DB_HOST"
echo "$DB_PORT"
until nc -z -v -w30 $DB_HOST $DB_PORT
do
  echo "Waiting for database connection..."
  sleep 3
done

echo -e "\nmysql ready\n"
echo -e "------------------start ngo------------------"
java $JAVA_OPTS -Djava.security.egd=file:/dev/./urandom -jar ngo.jar
echo -e "------------------ngo ready------------------"

编写Dockerfile#

Dockerfile 用来将我们的应用编译成image，然后通过把image部署到容器中向外提供服务，与之前不同的是我们通过

shell 脚本来启动服务

FROM openjdk:8-jdk-alpine
VOLUME /tmp
ARG JAVA_OPTS
ENV JAVA_OPTS=$JAVA_OPTS
COPY ./target/ngo-0.0.1-SNAPSHOT.jar ngo.jar
ADD ./docker/wait.sh wait.sh
CMD ["chmod", "+x", "wait.sh"]
ENTRYPOINT ["sh", "wait.sh"]

编写docker-compose#

docker-compose.yml文件中定义了两个服务spring-boot-gs-data，以及db. 这里有两种方式, 一是在容器内，二是通过docker-machin。与之前不同的是我们在这里将本地的初始化脚本copy到mysql container中的/docker-entrypoint-initdb.d目录，mysql启动时会使用此目录下的脚本初始化数据库

version: '3.3'
services:
  db:
    image: mysql
    container_name: mysql-container
    volumes:
      - ./docker/init_db.sql:/docker-entrypoint-initdb.d/init_db.sql
    environment:
      - MYSQL_USER=springuser
      - MYSQL_PASSWORD=ThePassword
      - MYSQL_DATABASE=db_example
      - MYSQL_ROOT_PASSWORD=root

  gs_data:
    build: .
    image: spring-boot-gs-data
    container_name: gs-data-container
    ports:
      - "8080:8080"
    depends_on:
      - db
    environment:
      - DB_HOST=db
      - DB_PORT=3306
      - DB_USER=springuser
      - DB_PASSWORD=ThePassword
      - DB_NAME=db_example

运行#

启动时只需要执行如下命令即可一次性部署db，和gs_data两个服务，具体是否还需要其他服务，可以依赖你的需求定制

docker-compose.yml

docker-compose up          //前台启动，启动时会在命令行打印相关的日志信息
docker-compose up -d       //后台启动

输出

docker-compose up
Building ngo                                  //编译NGO service
Step 1/8 : FROM openjdk:8-jdk-alpine
 ---> 97bc1352afde
Step 2/8 : VOLUME /tmp
 ---> Using cache
 ---> 6d58c198c55c
Step 3/8 : ARG JAVA_OPTS
 ---> Using cache
 ---> c3d1f12e9b40
Step 4/8 : ENV JAVA_OPTS=$JAVA_OPTS
 ---> Using cache
 ---> 0a9e45fe483a
Step 5/8 : COPY ./target/ngo-0.0.1-SNAPSHOT.jar ngo.jar
 ---> 08215ddc23c1
Step 6/8 : ADD ./docker/wait.sh wait.sh
 ---> 703a04395914
Step 7/8 : CMD ["chmod", "+x", "wait.sh"]
 ---> Running in 11499b449975
Removing intermediate container 11499b449975
 ---> 4caa2d7dd8f2
Step 8/8 : ENTRYPOINT ["sh", "wait.sh"]          //通过脚本来启动ngo 服务
 ---> Running in 42a5932ef9a2
Removing intermediate container 42a5932ef9a2
 ---> ffaf53498be9

Successfully built ffaf53498be9
Successfully tagged ngo:latest
WARNING: Image for service ngo was built because it did not already exist. To rebuild this image you must use `docker-compose build` or `docker-compose up --build`.
Creating mysql-container ... done
Creating server_ngo_1    ... done
Attaching to mysql-container, server_ngo_1
mysql-container | Initializing database
ngo_1  | Waiting for mysql
ngo_1  | db
ngo_1  | 3306

ngo_1  | Waiting for database connection...       //在数据库未启动时，会持续等待并打印此句
ngo_1  | db (172.18.0.2:3306) open
ngo_1  |
ngo_1  | mysql ready                              //数据库初始化完毕，启动ngo 服务
ngo_1  |
mysql-container | 2018-12-15T18:58:31.516026Z 0 [Note] mysqld: ready for connections.
mysql-container | Version: '5.7.24'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  MySQL Community Server (GPL)
ngo_1  | ------------------start ngo------------------
ngo_1  |

查看运行的container

docker ps -a
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                    NAMES
0ceb404fed0a        ngo                 "sh wait.sh chmod +x…"   21 minutes ago      Up 1 second         0.0.0.0:8080->8080/tcp   server_ngo_1
03a8a8cdf73d        mysql:5.7           "docker-entrypoint.s…"   21 minutes ago      Up 3 seconds

删除container，删除镜像使用docker rm 容器名即可，容器名可以通过docker ps查询

docker rm 0ceb404fed0a

删除镜像, 删除镜像之前保证没有container使用该镜像，如果有需要先删除container

docker image rm ngo

查看ngo container, 通过Dockefile我们把宿主机上的jar文件以及shell 脚本copy到了ngo container中，

docker exec -it 0ceb404fed0a ls -al     
total 53248
drwxr-xr-x    1 root     root          4096 Dec 15 18:58 .
drwxr-xr-x    1 root     root          4096 Dec 15 18:58 ..
-rwxr-xr-x    1 root     root             0 Dec 15 18:58 .dockerenv
drwxr-xr-x    2 root     root          4096 Sep 11 20:23 bin
drwxr-xr-x    5 root     root           340 Dec 15 19:19 dev
drwxr-xr-x    1 root     root          4096 Dec 15 18:58 etc
drwxr-xr-x    2 root     root          4096 Sep 11 20:23 home
drwxr-xr-x    1 root     root          4096 Oct 24 22:31 lib
drwxr-xr-x    5 root     root          4096 Sep 11 20:23 media
drwxr-xr-x    2 root     root          4096 Sep 11 20:23 mnt
-rw-r--r--    1 root     root      54456491 Dec 15 18:53 ngo.jar
dr-xr-xr-x  136 root     root             0 Dec 15 19:19 proc
drwx------    2 root     root          4096 Sep 11 20:23 root
drwxr-xr-x    2 root     root          4096 Sep 11 20:23 run
drwxr-xr-x    2 root     root          4096 Sep 11 20:23 sbin
drwxr-xr-x    2 root     root          4096 Sep 11 20:23 srv
dr-xr-xr-x   13 root     root             0 Dec 15 19:19 sys
drwxrwxrwt    5 root     root          4096 Dec 15 18:58 tmp
drwxr-xr-x    1 root     root          4096 Oct 24 22:31 usr
drwxr-xr-x    1 root     root          4096 Sep 11 20:23 var
-rw-r--r--    1 root     root           465 Dec 14 16:34 wait.sh

查看mysql container, 它是通过docker compose 自动部署的，

docker exec -it 03a8a8cdf73d bash

ls -al
total 80
drwxr-xr-x   1 root root 4096 Dec 15 18:58 .
drwxr-xr-x   1 root root 4096 Dec 15 18:58 ..
-rwxr-xr-x   1 root root    0 Dec 15 18:58 .dockerenv
drwxr-xr-x   1 root root 4096 Nov 16 01:14 bin
drwxr-xr-x   2 root root 4096 Oct 20 10:40 boot
drwxr-xr-x   5 root root  340 Dec 15 19:19 dev
drwxr-xr-x   1 root root 4096 Dec 15 18:58 docker-entrypoint-initdb.d
lrwxrwxrwx   1 root root   34 Nov 16 01:14 entrypoint.sh -> usr/local/bin/docker-entrypoint.sh
drwxr-xr-x   1 root root 4096 Dec 15 18:58 etc
drwxr-xr-x   2 root root 4096 Oct 20 10:40 home
drwxr-xr-x   1 root root 4096 Nov 12 00:00 lib
drwxr-xr-x   2 root root 4096 Nov 12 00:00 lib64
drwxr-xr-x   2 root root 4096 Nov 12 00:00 media
drwxr-xr-x   2 root root 4096 Nov 12 00:00 mnt
drwxr-xr-x   2 root root 4096 Nov 12 00:00 opt
dr-xr-xr-x 136 root root    0 Dec 15 19:19 proc
drwx------   1 root root 4096 Nov 16 01:11 root
drwxr-xr-x   1 root root 4096 Nov 16 01:14 run
drwxr-xr-x   2 root root 4096 Nov 12 00:00 sbin
drwxr-xr-x   2 root root 4096 Nov 12 00:00 srv
dr-xr-xr-x  13 root root    0 Dec 15 19:19 sys
drwxrwxrwt   1 root root 4096 Dec 15 19:19 tmp
drwxr-xr-x   1 root root 4096 Nov 12 00:00 usr
drwxr-xr-x   1 root root 4096 Nov 12 00:00 var

//当我们查看docker-entrypoint-initdb.d目录时会发现我们数据库的初始化脚本
//数据库启动的时候会执行此脚本

cd docker-entrypoint-initdb.d/
root@03a8a8cdf73d:/docker-entrypoint-initdb.d# ls
init_db.sql

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