Docker批量容器编排的实现

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)

docker-compose.yml

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