02. Install docker-compose under CentOS7

Install docker-compose under CentOS7

Docker Compose is a tool officially provided by Docker to define and run application services of multiple Docker containers through YAML files. It allows you to define multiple containers, networks, volumes, and other related configurations through a single configuration file, so as to realize container orchestration and management of application services.

Step 1: Install Docker

Before installing Docker Compose, you first need to install Docker on CentOS 7. You can install it as follows:

1. Update the system package:

sudo yum update -y

2. Install the required packages in order to use Docker's repository:

sudo yum install -y yum-utils device-mapper-persistent-data lvm2

3. Add Docker's official repository and Alibaba Cloud mirror library:

sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo

sudo yum-config-manager --add-repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

4. Install Docker Community Edition (CE):

sudo yum install -y docker-ce

5. Start the Docker service and set it to start automatically:

sudo systemctl enable docker

6. Verify that the Docker installation was successful:

docker --version

The installed Docker version information should be displayed.

Step 2: Install Docker Compose

After installing Docker, you can proceed to install Docker Compose. You can install it as follows:

1. Download the Docker Compose binary:

sudo curl -L https://github.com/docker/compose/releases/download/1.29.2/docker-compose-`uname -s`-`uname -m` -o /usr/local/bin/docker-compose

The Docker Compose 1.29.2 version is used here as an example, and you can update it according to the latest version information.

2. Authorize the execution permission of the binary file:

sudo chmod +x /usr/local/bin/docker-compose

3. Verify that the Docker Compose installation was successful:

docker-compose --version

The installed Docker Compose version information should be displayed.

Step 3: Configure Docker Compose

After installing Docker Compose, you can create a project directory and create a file named Docker in this directory docker-compose.ymlto define the configuration of the Docker service. It can be configured as follows:

1. Create a project directory:

cd my_docker_project

2. Create docker-compose.ymla file and edit:

nano docker-compose.yml

In this file, YAML syntax can be used to define configuration items of Docker services, including related configurations such as services, networks, and volumes. According to your needs and application scenarios, you can configure different services and associations.

3. Save and exit the editor.

Step 4: Manage Docker services with Docker Compose

After completing the configuration, you can use Docker Compose to manage the lifecycle of Docker services, including operations such as start, stop, restart, build, and delete. Here are some examples of commonly used commands:

• Start the service:

docker-compose up -d

• Out of service:

docker-compose down

• Restart the service:

docker-compose restart

• Build and start the service:

docker-compose up --build -d

• View service status:

docker-compose ps

• Check the service log:

docker-compose logs

This is just a small part of the functions of Docker Compose. For more commands and configuration items, please refer to the official documentation of Docker Compose.

Advantages of docker-compose

Key benefits of Docker Compose include:

1. Simplified container orchestration: With Docker Compose, you can centralize the configuration and management of multiple containers into a single YAML file, simplifying the complexity of container orchestration. You can define the relationship between containers, network connections, volume mounts, etc., so as to easily manage multi-container applications.
2. Repeatability and portability: With Docker Compose, you can define all the configuration and dependencies of the application in one file, thus realizing the repeatability and portability of the application. This means that you can easily deploy and manage applications in different environments without worrying about configuration differences and dependencies.
3. Scalability: Docker Compose supports horizontal expansion of applications by extending services. You can easily scale the capacity and performance of your application by defining the number of replicas for multiple instances in the configuration file.
4. Manage multi-container applications: Docker Compose provides a set of simple command-line tools for managing the life cycle of multi-container applications, including operations such as start, stop, restart, build, and delete. This allows you to easily manage the running and status of the entire application.

The configuration file of Docker Compose is in YAML format, which allows you to define multiple services, networks, volumes and other related configurations. A typical docker-compose.yml file contains the following main configuration items:

• services: defines the configuration of each service (that is, container), including information such as mirroring, port mapping, environment variables, and mounted volumes.
• networks: defines the network connection method between services, including connecting to the default network or custom network.
• volumes: defines the configuration of volumes for persistent data.
• configs and secrets: used to define how configuration files and sensitive information are managed.
• Environment variables: Environment variables can be set in the service configuration to pass configuration parameters for the application.

By writing a docker-compose.yml file, you can define the configuration and association of multiple services, and then use docker-composecommands to manage and orchestrate the entire application. For example, you can use docker-compose upcommands to start the application, use docker-compose downcommands to stop the application, use docker-compose pscommands to view the application's container status, and so on.

In general, Docker Compose is a powerful tool that can simplify the orchestration and management of multi-container applications, improve the repeatability, portability and scalability of applications, and is a very useful part of the Docker ecosystem.