Docker批量容器編排

calong發表於2020-09-12
Docker

Dockerfile build run是手動操作單個容器，假如使用微服務架構，需要啟動100+個容器，他們之間的依賴關係如何維護？
Docker Compose用來輕鬆高效地管理容器，定義執行多個容器。
三個步驟：

  • Dockerfile
  • Services & docker-compose.yml
  • docker-compose up
  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
version: "1.0" #版本
services: #服務列表
    service1:
        #服務配置
        container_name: #容器名稱
        depends_on: #依賴列表
        - depend1
        - depend2
        images: #映象
        - image1
        - image2
        build:. #構建目錄
        network: #網路
        ......
    service2: test2
        ......
volumnes: #掛載目錄列表
networks: #網路列表
configs: #其他配置
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