Detailed explanation of Docker Compose deployment and basic usage

1. Docker Compose Overview

Compose is a tool for defining and running multi-container Docker applications. With Compose, you use YAML files to configure your application's services. Then, with a single command, you can create and start all services from the configuration.

Compose works in all environments: production, staging, development, testing, and CI workflows.

Using Compose is basically a three-step process:

1. Define your application environment in a Dockerfile so it can be reproduced anywhere.
2. Define the services that make up your application in docker-compose.yml so that they can run together in isolated environments.
3. Run docker-compose up and Compose start and run the whole application.

An example of the docker-compose.yml format is as follows:

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

Compose has commands to manage the entire lifecycle of your application:

• Starting, stopping and rebuilding services
• View the status of running services
• Streaming log output from running services
• Run a one-time command on a service

2. Docker Compose Installation

2.1 Binary download and installation

 root@docker01:~# sudo curl -L "https://github.com/docker/compose/releases/download/1.22.0/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
root@docker01:~# sudo chmod +x /usr/local/bin/docker-compose

2.2 Installation with pip (recommended)

root@docker01:~# apt-get -y install python
root@docker01:~# curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
root@docker01:~# python get-pip.py #Install PIP
root@docker01:~# pip install docker-compose #Install docker compose
 root@docker01:~# docker-compose version #Verify installation

Three Docker Compose Examples

3.1 Building the Application

root@docker01:~# mkdir composetest #Create Docker Compose directoryroot@docker01:~# cd composetest/
root@docker01:~/composetest# vi app.py

Tip: Use Python to build a simple application. For specific application content, refer to the official example.
https://docs.docker.com/compose/gettingstarted/#step-1-setup

3.2 Create Dockerfile

root@docker01:~/composetest# vi Dockerfile #Use Dockerfile to build the image FROM python:3.4-alpine
RUN mkdir /root/.pip #Create pip source configuration directory ADD pip.conf /root/.pip/pip.conf #Add domestic pip source to the image to be built ADD ./code
WORKDIR /code
RUN pip install -r requirements.txt #Use pip to install according to the file list CMD ["python", "app.py"]

Tip: For the above Dockerfile related commands, refer to "004.Docker Image Management".

root@docker01:~/composetest# vi requirements.txt #Create installation software list file flask
redis
root@docker01:~/composetest# vi pip.conf #Create a file based on domestic pip source [global]
index-url = https://mirrors.aliyun.com/pypi/simple/
[install]
trusted-host=mirrors.aliyun.com

Dockerfile explained:

1. Build the image starting from the Python 3.4 image.
2. Create pip configuration directory.
3. Add the domestic pip source configuration file to the path in /root/.pip/ in your image.
4. Add the current directory . to the path in the /code image.
5. Set the working directory to /code.
6. Install Python related packages.
7. Set the container’s default command to python app.py.

3.3 Building Services with Docker Compose

root@docker01:~/composetest# vi docker-compose.yml
version: '3'
services:
 web:
  build: .
  ports:
   - "5000:5000"
 redis:
  image: "redis:alpine"

Docker Compose explained:

This Compose file defines two services, web and redis.

Web Services:

• Use the image built from the Dockerfile in the current directory.
• Forward the exposed port 5000 on the container to port 5000 on the host. That is, using the default port 5000 of the Flask web server.

redis service:

Use the public Redis image pulled from Docker Hub.

root@docker01:~/composetest# docker-compose up -d #Start building

Four verification confirmation

Browser access: http://172.24.8.111:5000/

root@docker01:~/composetest# docker-compose ps
root@docker01:~/composetest# docker ps 

 root@docker01:~/composetest# docker image ls 

hint:

The container name rule built using Docker Compose is: [directory where the build is located]_[service name defined in the yml build file]_[container startup sequence number].
The naming rule of the image built with Docker Compose is: [directory where the build is located]_[service name defined by the yml build file], and its tag is latest.

Five mount volume construction

root@docker01:~/composetest# vi docker-compose.yml
version: '3'
services:
 web:
  build: .
  ports:
   - "5000:5000"
  volumes:
   - .:/code
 redis:
  image: "redis:alpine"
root@docker01:~/composetest# docker-compose up -d #Build againroot@docker01:~/composetest# vi app.py
…
return 'Hello Docker! I have been seen {} times.\n'.format(count)
…

Browser access: http://172.24.8.111:5000/

Tip: After mounting a local volume to a container, you can quickly modify local files, thereby dynamically modifying the container without rebuilding the image.

6. Other common commands of Docker Compose

docker-compose up -d: runs the service in the background;
docker-compose ps: view the currently running containers;
docker-compose run: Runs a one-time command, such as docker-compose run web env. 

docker-compose stop: stop the service, such as docker-compose stop web

Tip: docker-compose takes the service name in yaml as a parameter, not the container name or ID.

docker-compose down --volumes: Completely delete the container and delete the data volumes used by the container.

The above is the full content of this article. I hope it will be helpful for everyone’s study. I also hope that everyone will support 123WORDPRESS.COM.