Docker 实战（四）：Docker Compose

Posted on 2016-12-01 Edited on 2024-09-11 In docker Views:

之前都是单个 Docker 容器，现在，基于 Docker Compose，你可以同时控制多个相关联的 Docker 容器。
比如典型的 Nginx + Tomcat + MySQL 的 Web 架构，只需要几个简单的配置，敲击几个命令，原来可能需要好几个小时的工作，现在几分钟就可以搞定。

使用 Compose 主要由以下三步组成：

定义 Dockerfile；
定义 docker-compose.yml；
运行 docker-compose up 启动所有容器。

这里会构造一个 HAProxy + 两个 Tomcat 负载均衡的架构。

docker-compose.yml

weba:
    build: ./web
    expose:
        - 8080

webb:
    build: ./web
    expose:
        - 8080

haproxy:
    image: haproxy:latest
    volumes:
        - ./haproxy:/haproxy-override
        - ./haproxy/haproxy.cfg:/usr/local/etc/haproxy/haproxy.cfg:ro
    links:
        - weba
        - webb
    ports:
        - "80:80"
        - "70:70"
    expose:
        - "80"
        - "70"

haproxy.cfg

global
  log 127.0.0.1	local0
  log 127.0.0.1	local1 notice
  maxconn 4096
  daemon

defaults
  log	global
  mode	http
  option	httplog
  option	dontlognull
  retries	3
  option redispatch
  maxconn	2000
  timeout connect	5000
  timeout client	50000
  timeout server	50000

frontend balancer
  bind 0.0.0.0:80
  mode http
  default_backend servers

backend servers
  option httpchk OPTIONS /
  option forwardfor
  cookie JSESSIONID prefix
  server tomcat1 weba:8080 cookie JSESSIONID_SERVER_1 check inter 5000
  server tomcat2 webb:8080 cookie JSESSIONID_SERVER_2 check inter 5000

listen status
  mode http
  default_backend servers
  bind 0.0.0.0:70
  stats enable
  stats hide-version
  stats uri     /stats
  stats auth    admin:password
  stats admin if TRUE

Dockerfile

FROM batizhao/java:8

# 创建者信息
MAINTAINER batizhao <zhaobati@gmail.com>

# Install dependencies
RUN apt-get update && \
    apt-get install -y wget tar && \
    apt-get clean && \
    rm -rf /var/lib/apt/lists/*

# Define commonly used JAVA_HOME variable
ENV TOMCAT_VERSION 8.5.8

# Get Tomcat
RUN wget --no-cookies http://ftp.jaist.ac.jp/pub/apache/tomcat/tomcat-8/v${TOMCAT_VERSION}/bin/apache-tomcat-${TOMCAT_VERSION}.tar.gz -O /tmp/tomcat.tgz && \
    tar xzvf /tmp/tomcat.tgz -C /opt && \
    mv /opt/apache-tomcat-${TOMCAT_VERSION} /opt/tomcat && \
    rm /tmp/tomcat.tgz && \
    rm -rf /opt/tomcat/webapps/examples && \
    rm -rf /opt/tomcat/webapps/docs && \
    rm -rf /opt/tomcat/webapps/manager && \
    rm -rf /opt/tomcat/webapps/host-manager && \
    rm -rf /opt/tomcat/webapps/ROOT/*

ADD index.html /opt/tomcat/webapps/ROOT

ENV CATALINA_HOME /opt/tomcat
ENV PATH $PATH:$CATALINA_HOME/bin

EXPOSE 8080
WORKDIR /opt/tomcat

# Launch Tomcat
CMD ["/opt/tomcat/bin/catalina.sh", "run"]

index.html

1	Hello, Docker.

启动容器

$ docker-compose up
Creating composehaproxyweb_webb_1
Creating composehaproxyweb_weba_1
Creating composehaproxyweb_haproxy_1
Attaching to composehaproxyweb_weba_1, composehaproxyweb_webb_1, composehaproxyweb_haproxy_1
haproxy_1  | <7>haproxy-systemd-wrapper: executing /usr/local/sbin/haproxy -p /run/haproxy.pid -f /usr/local/etc/haproxy/haproxy.cfg -Ds
webb_1     | 30-Nov-2016 12:50:21.524 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server version:        Apache Tomcat/8.5.8
weba_1     | 30-Nov-2016 12:50:21.531 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server version:        Apache Tomcat/8.5.8
...

访问 http://localhost
可以看到 Hello, Docker.

访问 http://localhost:70/stats

后台运行

增加 -d 参数

$ docker-compose up -d
Starting composehaproxyweb_webb_1
Starting composehaproxyweb_weba_1
Starting composehaproxyweb_haproxy_1

查看 compose 进程

$ docker-compose ps
           Name                          Command               State                   Ports
-------------------------------------------------------------------------------------------------------------
composehaproxyweb_haproxy_1   /docker-entrypoint.sh hapr ...   Up      0.0.0.0:70->70/tcp, 0.0.0.0:80->80/tcp
composehaproxyweb_weba_1      /opt/tomcat/bin/catalina.s ...   Up      8080/tcp
composehaproxyweb_webb_1      /opt/tomcat/bin/catalina.s ...   Up      8080/tcp

在 weba 上执行命令，比如 env

$ docker-compose run weba env
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/opt/tomcat/bin
HOSTNAME=4fd738ffc9b2
TERM=xterm
COMPOSEHAPROXYWEB_WEBA_1_PORT=tcp://172.17.0.2:8080
COMPOSEHAPROXYWEB_WEBA_1_PORT_8080_TCP=tcp://172.17.0.2:8080
COMPOSEHAPROXYWEB_WEBA_1_PORT_8080_TCP_ADDR=172.17.0.2
COMPOSEHAPROXYWEB_WEBA_1_PORT_8080_TCP_PORT=8080
COMPOSEHAPROXYWEB_WEBA_1_PORT_8080_TCP_PROTO=tcp
COMPOSEHAPROXYWEB_WEBA_1_NAME=/composehaproxyweb_weba_run_1/composehaproxyweb_weba_1
COMPOSEHAPROXYWEB_WEBA_1_ENV_TOMCAT_VERSION=8.5.8
COMPOSEHAPROXYWEB_WEBA_1_ENV_CATALINA_HOME=/opt/tomcat
WEBA_PORT=tcp://172.17.0.2:8080
WEBA_PORT_8080_TCP=tcp://172.17.0.2:8080
WEBA_PORT_8080_TCP_ADDR=172.17.0.2
WEBA_PORT_8080_TCP_PORT=8080
WEBA_PORT_8080_TCP_PROTO=tcp
WEBA_NAME=/composehaproxyweb_weba_run_1/weba
WEBA_ENV_TOMCAT_VERSION=8.5.8
WEBA_ENV_CATALINA_HOME=/opt/tomcat
WEBA_1_PORT=tcp://172.17.0.2:8080
WEBA_1_PORT_8080_TCP=tcp://172.17.0.2:8080
WEBA_1_PORT_8080_TCP_ADDR=172.17.0.2
WEBA_1_PORT_8080_TCP_PORT=8080
WEBA_1_PORT_8080_TCP_PROTO=tcp
WEBA_1_NAME=/composehaproxyweb_weba_run_1/weba_1
WEBA_1_ENV_TOMCAT_VERSION=8.5.8
WEBA_1_ENV_CATALINA_HOME=/opt/tomcat
TOMCAT_VERSION=8.5.8
CATALINA_HOME=/opt/tomcat
HOME=/root

停止后台进程

$ docker-compose stop
Stopping composehaproxyweb_haproxy_1 ... done
Stopping composehaproxyweb_webb_1 ... done
Stopping composehaproxyweb_weba_1 ... done

问题

No such image

这是缓存造成的一个问题，可能由于你直接手动删除了 compose 生成的 image。
你可以通过 docker-compose ps 查看，也通过 docker-compose rm 直接清除。
想要避免这个问题，你需要 docker-compose down。

目录