简介

Dockerfile build run是手动操作单个容器，假如使用微服务架构，需要启动100+个容器，他们之间的依赖关系如何维护？
Docker Compose用来轻松高效地管理容器，定义运行多个容器。
三个步骤：

• Dockerfile
• Services & docker-compose.yml
• docker-compose up

初体验

1. Dockerfile

   FROM python:3.7-alpine
   WORKDIR /code
   ENV FLASK_APP app.py
   ENV FLASK_RUN_HOST 0.0.0.0
   RUN apk add --no-cache gcc musl-dev linux-headers
   COPY requirements.txt requirements.txt
   RUN pip install -r requirements.txt
   COPY . .
   CMD ["flask", "run"]

2.Service

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 World! I have been seen {} times.\n'.format(count)

3. docker-compose.yml

   version: '3'
   services:
   web:
    build: .
    ports:
   - "5000:5000"
    volumes:
   - .:/code
    - logvolume01:/var/log
    links:
   - redis
   redis:
    image: redis
   volumes:
   logvolume01: {}

4. docker-compose up

   Starting compose-demo_web_1   ... done
   Starting compose-demo_redis_1 ... done
   Attaching to compose-demo_redis_1, compose-demo_web_1
   redis_1  | 1:C 12 Sep 2020 07:34:09.654 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
   redis_1  | 1:C 12 Sep 2020 07:34:09.655 # Redis version=6.0.7, bits=64, commit=00000000, modified=0, pid=1, just started
   redis_1  | 1:C 12 Sep 2020 07:34:09.655 # 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 12 Sep 2020 07:34:09.657 * Running mode=standalone, port=6379.
   redis_1  | 1:M 12 Sep 2020 07:34:09.657 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
   redis_1  | 1:M 12 Sep 2020 07:34:09.657 # Server initialized
   redis_1  | 1:M 12 Sep 2020 07:34:09.658 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
   redis_1  | 1:M 12 Sep 2020 07:34:09.658 * Loading RDB produced by version 6.0.7
   redis_1  | 1:M 12 Sep 2020 07:34:09.658 * RDB age 156 seconds
   redis_1  | 1:M 12 Sep 2020 07:34:09.658 * RDB memory usage when created 0.77 Mb
   redis_1  | 1:M 12 Sep 2020 07:34:09.658 * DB loaded from disk: 0.000 seconds
   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

YML文件规则

version: "1.0" #版本
services: #服务列表
    service1:
        #服务配置
        container_name: #容器名称
        depends_on: #依赖列表
        - depend1
        - depend2
        images: #镜像
        - image1
        - image2
        build:. #构建目录
        network: #网络
        ......
    service2: test2
        ......
volumnes: #挂载目录列表
networks: #网络列表
configs: #其他配置

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