Docker批量容器编排

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)
  1. docker-compose.yml
    version: '3'
    services:
    web:
     build: .
     ports:
    - "5000:5000"
     volumes:
    - .:/code
     - logvolume01:/var/log
     links:
    - redis
    redis:
     image: redis
    volumes:
    logvolume01: {}
  1. 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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