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8.使用Docker Compose管理多个容器

Docker Compose是一个用来定义和运行复杂应用的Docker工具。使用Compose,你可以在一个文件中定义一个多容器应用,然后使用一条命令来启动你的应用,完成一切准备工作。

- github.com/docker/compose

一个使用Docker容器的应用,通常由多个容器组成。使用Docker Compose,不再需要使用shell脚本来启动容器。在配置文件中,所有的容器通过 services 来定义,然后使用 docker-compose 脚本来启动,停止和重启应用,和应用中的服务以及所有依赖服务的容器。完整的命令列表如下:

build 构建或重建服务

help 命令帮助

kill 杀掉容器

logs 显示容器的输出内容

port 打印绑定的开放端口

ps 显示容器

pull 拉取服务镜像

restart 重启服务

rm 删除停止的容器

run 运行一个一次性命令

scale 设置服务的容器数目

start 开启服务

stop 停止服务

up 创建并启动容器

参考 https://docs.docker.com/compose/install/ 。你能运行Compose在OSX和64位Linux。当前不支持Windows操作系统。

8.1. 安装Docker Compose

curl -L https://github.com/docker/compose/releases/download/1.4.2/docker-compose-`uname -s`-`uname -m` > /usr/local/bin/docker-compose
chmod x /usr/local/bin/docker-compose

8.2. 配置文件

1.Compose的配置文件是 docker-compose.yml 。让我们看看下面这个文件:

mysqldb:
image: [classroom.example.com:5000/]mysql
environment:
MYSQL_DATABASE: sample
MYSQL_USER: mysql
MYSQL_PASSWORD: mysql
MYSQL_ROOT_PASSWORD: supersecret
mywildfly:
image: [classroom.example.com:5000|arungupta]/wildfly-mysql-javaee7
links:
- mysqldb:db
ports:
- 8080

这个文件在 https://raw.githubusercontent. ... dees/ ,它表明:

a. 定义了两个服务分别叫做 mysqldbmywildfy

b. 使用 image 定义每个服务的镜像名

c. MySQL容器的环境变量定义在 environment

d. MySQL容器使用 links 和WildFly容器链接

e. 使用 ports 实现端口转发

8.3. 启动服务

1. 如果你从互联网运行,将 docker-compose-internet.yml 保存为 docker-compose.yml

  1. 如果你使用教师给的镜像,将 docker-compose-instructor.yml 保存为 docker-compose.yml
  2. 使用下面的命令,所有的服务将使用后台模式被启动
    docker-compose up -d
    显示的输出如下:
    Creating attendees_mysqldb_1...
    Creating attendees_mywildfly_1...

    使用 -f 指定代替的compose文件。
    使用 -p 指定代替compose文件所在的目录。
  3. 验证启动的服务
    docker-compose ps
    Name Command State Ports
    attendees_mysqldb_1 /entrypoint.sh mysqld Up 3306/tcp
    attendees_mywildfly_1 /opt/jboss/wildfly/customi ... Up 0.0.0.0:32773->8080/tcp
    这里提供了一个整合的列表显示所有启动的服务和容器。

同时,通常使用 docker ps 命令来验证应用的容器,和在Docker主机上运行的其他容器。

docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
3598e545bd2f arungupta/wildfly-mysql-javaee7:latest "/opt/jboss/wildfly/ 59 seconds ago Up 58 seconds 0.0.0.0:32773->8080/tcp attendees_mywildfly_1
b8cf6a3d518b mysql:latest "/entrypoint.sh mysq 2 minutes ago Up 2 minutes 3306/tcp attendees_mysqldb_1
  1. 查询服务日志

    {{{

    taching to attendees_mywildfly_1, attendees_mysqldb_1

    mywildfly_1 | => Starting WildFly server

    mywildfly_1 | => Waiting for the server to boot

    mywildfly_1 | =========================================================================

    mywildfly_1 |

    mywildfly_1 | JBoss Bootstrap Environment

    mywildfly_1 |

    mywildfly_1 | JBOSS_HOME: /opt/jboss/wildfly

    mywildfly_1 |

    mywildfly_1 | JAVA: /usr/lib/jvm/java/bin/java

    mywildfly_1 |

    mywildfly_1 | JAVA_OPTS: -server -Xms64m -Xmx512m -XX:MaxPermSize=256m -Djava.net.preferIPv4Stack=true -Djboss.modules.system.pkgs=org.jboss.byteman -Djava.awt.headless=true

    mywildfly_1 |

. . .

mywildfly_1 | 15:40:20,866 INFO [org.jboss.resteasy.spi.ResteasyDeployment] (MSC service thread 1-2) Deploying javax.ws.rs.core.Application: class org.javaee7.samples.employees.MyApplication

mywildfly_1 | 15:40:20,914 INFO [org.wildfly.extension.undertow] (MSC service thread 1-2) JBAS017534: Registered web context: /employees

mywildfly_1 | 15:40:21,032 INFO [org.jboss.as.server] (ServerService Thread Pool -- 28) JBAS018559: Deployed "employees.war" (runtime-name : "employees.war")

mywildfly_1 | 15:40:21,077 INFO [org.jboss.as] (Controller Boot Thread) JBAS015961: Http management interface listening on http://127.0.0.1:9990/management

mywildfly_1 | 15:40:21,077 INFO [org.jboss.as] (Controller Boot Thread) JBAS015951: Admin console listening on http://127.0.0.1:9990

mywildfly_1 | 15:40:21,077 INFO [org.jboss.as] (Controller Boot Thread) JBAS015874: WildFly 8.2.0.Final "Tweek" started in 9572ms - Started 280 of 334 services (92 services are lazy, passive or on-demand)

mysqldb_1 | Running mysql_install_db

mysqldb_1 | 2015-06-05 15:38:31 0 [Note] /usr/sbin/mysqld (mysqld 5.6.25) starting as process 27 ...

mysqldb_1 | 2015-06-05 15:38:31 27 [Note] InnoDB: Using atomics to ref count buffer pool pages

. . .

mysqldb_1 | 2015-06-05 15:38:40 1 [Note] Event Scheduler: Loaded 0 events

mysqldb_1 | 2015-06-05 15:38:40 1 [Note] mysqld: ready for connections.

mysqldb_1 | Version: '5.6.25' socket: '/var/run/mysqld/mysqld.sock' port: 3306 MySQL Community Server (GPL)

mysqldb_1 | 2015-06-05 15:40:18 1 [Warning] IP address '172.17.0.24' could not be resolved: Name or service not known

}}}

8.4. 验证应用

  1. 通过 http://dockerhost:32773/employ ... yees/ 访问应用。在浏览器里显示如下:

    > 使用 docker-compose ps 命令显示端口

    8.使用Docker Compose管理多个容器

8.5. 扩展服务

你能像这样扩展服务:

docker-compose scale mywildfly=4
Creating and starting 2... done
Creating and starting 3... done
Creating and starting 4... done

检查日志:

docker-compose logs

检查运行的实例:

docker-compose ps

Name Command State Ports

rafael_mysqldb_1 /entrypoint.sh mysqld Up 3306/tcp

rafael_mywildfly_1 /opt/jboss/wildfly/customi ... Up 0.0.0.0:32773->8080/tcp

rafael_mywildfly_2 /opt/jboss/wildfly/customi ... Up 0.0.0.0:32777->8080/tcp

rafael_mywildfly_3 /opt/jboss/wildfly/customi ... Up 0.0.0.0:32780->8080/tcp

rafael_mywildfly_4 /opt/jboss/wildfly/customi ... Up 0.0.0.0:32781->8080/tcp

你也能减少运行的实例数目:

docker-compose scale mywildfly=2
Stopping rafael_mywildfly_3... done
Stopping rafael_mywildfly_4... done
Removing rafael_mywildfly_3... done
Removing rafael_mywildfly_4... done

8.6. 停止服务

停止服务:

docker-compose stop
Stopping attendees_mywildfly_1...
Stopping attendees_mywildfly_2...
Stopping attendees_mysqldb_1...

警告:再次停止和启动将会得到如下错误:

wildfly_1 |
wildfly_1 | 09:11:07,802 ERROR [org.jboss.as.controller.management-operation] (management-handler-thread - 4) JBAS014613: Operation ("add") failed - address: ([
wildfly_1 | ("subsystem" => "datasources"),
wildfly_1 | ("jdbc-driver" => "mysql")
wildfly_1 | ]) - failure description: "JBAS014803: Duplicate resource [
wildfly_1 | (/"subsystem/" => /"datasources/"),
wildfly_1 | (/"jdbc-driver/" => /"mysql/")
wildfly_1 | ]"

这是因为JDBC资源在每个运行的容器中创建,在实际情况下,这是已经写在配置中的。

原文链接: Multiple Containers Using Docker Compose

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