Docker-compose: Docker-compose

Docker-compose is the official open source container creation, multi-container orchestration tool.

We know that a complete application system often consists of multiple containers that provide services mutually. For example, if a Web application needs to contain Web services, databases, etc., docker-compose can be easily used to control and manage multiple containers.

Open source: github.com/docker/comp…

Docker-compose installation

Docker-compose is written in Python and can be installed via PIP package management

PIP install docker - compose # or yum install wget https://repo.huaweicloud.com/docker-ce/linux/centos/docker-ce.repo - O D /docker-ce. Repo yum install docker-compose # clone GitHubreleaseCopy the code

Docker-compose is composed by docker-compose

Docker Compose manages three layers of containers, which are project, Service and Container.

The docker-compose. Yml file resides in the docker-compose project. A project contains multiple services, and each service defines the image, container name, port, network and other parameters of the container. That is, a service can contain multiple container instances.

A docker-comemage. yml file is shown below

version: '2.3'  
services:
  log:
    image: Goharbor/harbor - log: v2.1.5
    container_name: harbor-log
    restart: always
    dns_search: .
    cap_drop:
      - ALL
    cap_add:
      - CHOWN
      - DAC_OVERRIDE
      - SETGID
      - SETUID
    volumes:
      - /var/log/harbor/:/var/log/docker/:z
      - type: bind
        source: ./common/config/log/logrotate.conf
        target: /etc/logrotate.d/logrotate.conf
      - type: bind
        source: ./common/config/log/rsyslog_docker.conf
        target: /etc/rsyslog.d/rsyslog_docker.conf
    ports:
      - 127.0. 01.: 1514-10514
    networks:
      - harbor
  registry:
    image: Goharbor/registry - photon: v2.1.5
    container_name: registry
    restart: always
    .
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Docker-compose docker-compose

  • Ps: Lists all running containers
docker-compose ps
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  • Logs: View service log output
docker-compose logs
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  • Build: Builds or rebuilds the service
docker-compose build
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  • Start: starts an existing container for the specified service
docker-compose start nginx
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  • Stop: stops a container for running services
docker-compose stop nginx
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  • Rm: Delete the container of the specified service
docker-compose rm nginx
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  • Up: Builds and starts the container
docker-compose up
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  • Kill: Stops a container for a specified service by sending the SIGKILL signal
docker-compose kill nginx
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  • Pull: Downloads the service image
Version: '2' services: db: image: postgres Web: build:. Command: bundle exec Rails s-p 3000-b '0.0.0.0' volumes: - .:/myapp ports: - "3000:3000" depends_on: - db $ docker-compose pull db Pulling db (postgres:latest)... latest: Pulling from library/postgres cd0a524342ef: Pull complete 9c784d04dcb0: Pull complete d99dddf7e662: Pull complete e5bff71e3ce6: Pull complete cb3e0a865488: Pull complete 31295d654cd5: Pull complete fc930a4e09f5: Pull complete 8650cce8ef01: Pull complete 61949acd8e52: Pull complete 527a203588c0: Pull complete 26dec14ac775: Pull complete 0efc0ed5a9e5: Pull complete 40cd26695b38: Pull complete Digest: sha256:fd6c0e2a9d053bebb294bb13765b3e01be7817bf77b01d58c2377ff27a4a46dc Status: Downloaded newer image for postgres:latestCopy the code
  • Scale: Sets the number of containers for the specified service luck.
docker-compose scale nginx=3 redis=3
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  • Run: Executes a command on a service
docker-compose run web bash
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For details about commands and descriptions, see the official documentsDocs.docker.com/compose/ref…

Docker-compose practice

Deploy a Python Web application using Docker-compose.

1. Create a project directory
 mkdir mycompose
 cd mycompose
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2. Create a flask application app.py
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)
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3. Create arequirements.txt
flask
redis
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4. CreateDockerfilefile
# syntax=docker/dockerfile:1 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  EXPOSE 5000 COPY . . CMD ["flask", "run"]Copy the code
5. Create yoursdocker-compose.ymlContains two containers, Web and Redis
Version: "3.0" Services: Web: build:. Ports: - "5000:5000" Redis: image: "Redis :alpine"Copy the code
6. Build and run docker-compose project
[root@VM-0-5-centos mycompose]# ls app.py docker-compose. Yml Dockerfile requirements. TXT docker-compose upCopy the code

Start building the container

Docker PS can check that the two containers have been up

Verify the installation http://ip. The following installation is complete.

Update docker-comemage. yml to add mount

Version: "3.0" Services: web: build:. Ports: - "5000:5000" volumes: -.:/code environment: FLASK_ENV: development redis: image: "redis:alpine"Copy the code

Edit app. Py

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(): raise exc retries -= 1 time.sleep(0.5) @app.route('/') def hello(): Get_hit_count () return 'I have been seen {} times.\n'. Format (count) #Copy the code

Rebuild the Web container

[root@VM-0-5-centos mycompose]# docker-compose up -d
Starting mycompose_web_1 ... 
Starting mycompose_web_1 ... done
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The web page is as follows:

Docker – compose basis after use, in-depth study refer to official document docs.docker.com/compose/ref…

Feel free to point out any shortcomings in the comments section.

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