docker-compose 使用介绍

简介

Docker-Compose项目是Docker官方的开源项目，负责实现对Docker容器集群的快速编排。Compose允许用户通过一个单独的docker-compose.yml模板文件（YAML 格式）来定义一组相关联的应用容器为一个项目（project）。Docker-Compose项目由Python编写，调用Docker服务提供的API来对容器进行管理。因此，只要所操作的平台支持Docker API，就可以在其上利用Compose来进行编排管理。

Docker-Compose将所管理的容器分为三层，分别是工程（project），服务（service）以及容器（container）。Docker-Compose运行目录下的所有文件（docker-compose.yml，extends文件或环境变量文件等）组成一个工程，若无特殊指定工程名即为当前目录名。一个工程当中可包含多个服务，每个服务中定义了容器运行的镜像，参数，依赖。一个服务当中可包括多个容器实例，Docker-Compose并没有解决负载均衡的问题，因此需要借助其它工具实现服务发现及负载均衡。

Docker-Compose的工程配置文件默认为docker-compose.yml，可通过环境变量COMPOSE_FILE或-f参数自定义配置文件，其定义了多个有依赖关系的服务及每个服务运行的容器。
使用一个Dockerfile模板文件，可以让用户很方便的定义一个单独的应用容器。在工作中，经常会碰到需要多个容器相互配合来完成某项任务的情况。例如要实现一个Web项目，除了Web服务容器本身，往往还需要再加上后端的数据库服务容器，甚至还包括负载均衡容器等。

Docker-compose常用命令

• 查看配置：docker-compose config
• 后台启动：docker-compose up -d
• 构建镜像：docker-compose build
• 下载镜像：docker-compose pull
• 运行的：docker-compose ps
• 进程：docker-compose top
• 启动： docker-compose start
• 停止：docker-compose stop

docker-compose 模版文件

Compose允许用户通过一个docker-compose.yml模板文件（YAML 格式）来定义一组相关联的应用容器为一个项目（project）。
Compose模板文件是一个定义服务、网络和卷的YAML文件。Compose模板文件默认路径是当前目录下的docker-compose.yml，可以使用.yml或.yaml作为文件扩展名。
Docker-Compose标准模板文件应该包含version、services、networks 三大部分，最关键的是services和networks两个部分。

version: "2.1"
services:
  img-name:
    image: xxxx

Compose目前有三个版本分别为Version 1，Version 2，Version 3，Compose区分Version 1和Version 2（Compose 1.6.0+，Docker Engine 1.10.0+）。Version 2支持更多的指令。Version 1将来会被弃用。

挂载文件
docker-compose支持两种方式设置持久化的文件

servicename:
  image: image-name
  volumes:
  - /path/to/file:/path/to/container/file

这种方式将文件直接挂载到容器中，使用起来比较直观，但是需要管理本地路径。

servicename:
  image: image-name
  volumes:
  - volume-name:/path/to/container/file
volumes:
  volume-name: /path/to/local/file

使用docker volume ls命令可以查看本地挂载的文件。
使用docker volume inspect volume-name命令可以查看具体的真实地址。

具体示例

chenshifengdeMacBook-Pro:docker-compose chenshifeng$ pwd
/Users/chenshifeng/docker/docker-compose
chenshifengdeMacBook-Pro:docker-compose chenshifeng$ ls -a
.                  ..                 .env               Dockerfile         app.py             docker-compose.yml

docker-compose.yml 文件

version: '3'
services: 
  web:
    build: 
      context: .
    depends_on: 
      - redis
    ports: 
      - "5000:5000"

  redis:
    image: ${REDIS_VERSION}
    restart: always

Dockerfile

FROM python:3.7-alpine
LABEL maintainer="shifeng"

#将工作路径设定为/code
WORKDIR /code

#创建环境变量给 Flask 使用
ENV FLASK_APP app.py
ENV FLASK_RUN_HOST 0.0.0.0

#复制 app.py 到容器内 /code 目录
COPY app.py /code

#安装 gcc 工具、python 的依赖
RUN pip install flask && pip install redis

#映射端口
EXPOSE 5000

STOPSIGNAL SIGTERM

#为容器设置默认启动命令
CMD ["flask","run"]

app.py文件

import time
import redis
from flask import Flask

app = Flask(__name__)
cache = redis.Redis(host='redis',port=6379)

def get_hit_count():
    retries = 5
    while True:
        try:
            return cache.incr('hits')
        except redis.exceptions.ConnectionError as exc:
            if retries == 0:
                raise exc
            retries -= 1
            time.sleep(0.5)

@app.route('/')
def hello():
    count = get_hit_count()
    return 'Hello Wirld! I have been see {} times.
'.format(count)

.env 文件

REDIS_VERSION=redis:alpine

chenshifengdeMacBook-Pro:docker-compose chenshifeng$ docker-compose up
Creating network "docker-compose_default" with the default driver
Pulling redis (redis:alpine)...
alpine: Pulling from library/redis
801bfaa63ef2: Pull complete
9a8d0188e481: Pull complete
8a3f5c4e0176: Pull complete
51a20dbe2f6a: Pull complete
0aacff13b8d7: Pull complete
adc9264cf133: Pull complete
Digest: sha256:68d4030e07912c418332ba6fdab4ac69f0293d9b1daaed4f1f77bdeb0a5eb048
Status: Downloaded newer image for redis:alpine
Building web
Step 1/10 : FROM python:3.7-alpine
3.7-alpine: Pulling from library/python
801bfaa63ef2: Already exists
7678dd7631a2: Pull complete
673b2cf6feb8: Pull complete
924474d3e184: Pull complete
3531f307fdb1: Pull complete
Digest: sha256:a73d0fdab3235920c0df44d55c420e2c3096f1b1a95e5f913a0287eee4192bdb
Status: Downloaded newer image for python:3.7-alpine
 ---> 72e4ef8abf8e
Step 2/10 : LABEL maintainer="shifeng"
 ---> Running in 793121c1f8dd
Removing intermediate container 793121c1f8dd
 ---> ed4aff0b54e8
Step 3/10 : WORKDIR /code
 ---> Running in 98ee8098e153
Removing intermediate container 98ee8098e153
 ---> 4900195b572f
Step 4/10 : ENV FLASK_APP app.py
 ---> Running in 3e2758418f80
Removing intermediate container 3e2758418f80
 ---> 171470c2ac1b
Step 5/10 : ENV FLASK_RUN_HOST 0.0.0.0
 ---> Running in 04b8ad3e08a7
Removing intermediate container 04b8ad3e08a7
 ---> 1347210f446e
Step 6/10 : COPY app.py /code
 ---> 7e5a2528c571
Step 7/10 : RUN pip install flask && pip install redis
 ---> Running in 0e844207fd06
Collecting flask
  Downloading Flask-1.1.2-py2.py3-none-any.whl (94 kB)
Collecting click>=5.1
  Downloading click-7.1.2-py2.py3-none-any.whl (82 kB)
Collecting itsdangerous>=0.24
  Downloading itsdangerous-1.1.0-py2.py3-none-any.whl (16 kB)
Collecting Jinja2>=2.10.1
  Downloading Jinja2-2.11.2-py2.py3-none-any.whl (125 kB)
Collecting MarkupSafe>=0.23
  Downloading MarkupSafe-1.1.1.tar.gz (19 kB)
Collecting Werkzeug>=0.15
  Downloading Werkzeug-1.0.1-py2.py3-none-any.whl (298 kB)
Building wheels for collected packages: MarkupSafe
  Building wheel for MarkupSafe (setup.py): started
  Building wheel for MarkupSafe (setup.py): finished with status 'done'
  Created wheel for MarkupSafe: filename=MarkupSafe-1.1.1-py3-none-any.whl size=12629 sha256=5645144c3e873524880c2e8ece40cc7d195ef92acf2d7e2f4fbbdca8959411ac
  Stored in directory: /root/.cache/pip/wheels/b9/d9/ae/63bf9056b0a22b13ade9f6b9e08187c1bb71c47ef21a8c9924
Successfully built MarkupSafe
Installing collected packages: MarkupSafe, Werkzeug, Jinja2, itsdangerous, click, flask
Successfully installed Jinja2-2.11.2 MarkupSafe-1.1.1 Werkzeug-1.0.1 click-7.1.2 flask-1.1.2 itsdangerous-1.1.0
Collecting redis
  Downloading redis-3.5.3-py2.py3-none-any.whl (72 kB)
Installing collected packages: redis
Successfully installed redis-3.5.3
Removing intermediate container 0e844207fd06
 ---> 53a70dd92c04
Step 8/10 : EXPOSE 5000
 ---> Running in 6987bd583661
Removing intermediate container 6987bd583661
 ---> e20fb875f578
Step 9/10 : STOPSIGNAL SIGTERM
 ---> Running in 31e0f0933348
Removing intermediate container 31e0f0933348
 ---> 48291e02cb4e
Step 10/10 : CMD ["flask","run"]
 ---> Running in 9405853c0548
Removing intermediate container 9405853c0548
 ---> bce891d25361

Successfully built bce891d25361
Successfully tagged docker-compose_web:latest
WARNING: Image for service web was built because it did not already exist. To rebuild this image you must use `docker-compose build` or `docker-compose up --build`.
Creating docker-compose_redis_1 ... done
Creating docker-compose_web_1   ... done
Attaching to docker-compose_redis_1, docker-compose_web_1
redis_1  | 1:C 05 Jan 2021 15:53:41.991 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
redis_1  | 1:C 05 Jan 2021 15:53:41.991 # Redis version=6.0.9, bits=64, commit=00000000, modified=0, pid=1, just started
redis_1  | 1:C 05 Jan 2021 15:53:41.991 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
redis_1  | 1:M 05 Jan 2021 15:53:41.993 * Running mode=standalone, port=6379.
redis_1  | 1:M 05 Jan 2021 15:53:41.994 # Server initialized
redis_1  | 1:M 05 Jan 2021 15:53:41.995 * Ready to accept connections
web_1    |  * Serving Flask app "app.py"
web_1    |  * Environment: production
web_1    |    WARNING: This is a development server. Do not use it in a production deployment.
web_1    |    Use a production WSGI server instead.
web_1    |  * Debug mode: off
web_1    |  * Running on http://0.0.0.0:5000/ (Press CTRL+C to quit)
web_1    | 172.20.0.1 - - [05/Jan/2021 15:53:58] "GET / HTTP/1.1" 200 -
web_1    | 172.20.0.1 - - [05/Jan/2021 15:53:59] "GET /favicon.ico HTTP/1.1" 404 -
web_1    | 172.20.0.1 - - [05/Jan/2021 15:54:01] "GET / HTTP/1.1" 200 -

chenshifengdeMacBook-Pro:docker-compose chenshifeng$ docker-compose ps
         Name                       Command               State           Ports         
----------------------------------------------------------------------------------------
docker-compose_redis_1   docker-entrypoint.sh redis ...   Up      6379/tcp              
docker-compose_web_1     flask run                        Up      0.0.0.0:5000->5000/tcp

chenshifengdeMacBook-Pro:docker-compose chenshifeng$ docker-compose top
docker-compose_redis_1
 PID    USER   TIME     COMMAND   
----------------------------------
17626   999    0:03   redis-server

docker-compose_web_1
 PID    USER   TIME                          COMMAND                        
----------------------------------------------------------------------------
17732   root   0:00   {flask} /usr/local/bin/python /usr/local/bin/flask run