How To Install Docker Compose on AlmaLinux 9

Docker has revolutionized the way developers and system administrators deploy and manage applications. By leveraging containerization technology, Docker allows applications to be packaged with their dependencies, ensuring consistency across different environments. Docker Compose, a powerful tool in the Docker ecosystem, simplifies the management of multi-container applications. It enables you to define and run complex applications using a single configuration file, making it easier to set up and orchestrate multiple services. In this article, we will guide you through the process of installing Docker Compose on AlmaLinux 9, a stable and open-source Linux distribution.

Prerequisites

Before we dive into the installation process, ensure that your system meets the following requirements:

• AlmaLinux 9 installed on your system
• A user account with sudo privileges
• Internet connectivity to download the necessary packages

If you have any older versions of Docker or Docker Compose installed, it’s recommended to remove them to avoid conflicts. You can do this by running the following command:

sudo dnf remove docker docker-compose

Step 1: Update System Packages

To ensure that your AlmaLinux 9 system is up to date, run the following command:

sudo dnf update -y

This command will update all the installed packages to their latest versions, providing you with the latest bug fixes, security patches, and improvements.

Step 2: Install Docker

Before installing Docker Compose, you need to have Docker installed on your AlmaLinux 9 system. Follow these steps to install Docker:

Add Docker Repository

To install Docker, you need to add the official Docker repository to your system. This ensures that you have access to the latest version of Docker. Run the following command to add the repository:

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

Install Docker Engine

With the Docker repository added, you can now install the Docker Engine. Execute the following command:

sudo dnf install docker-ce docker-ce-cli containerd.io

This command will install the Docker Community Edition (CE) along with the command-line interface (CLI) and the containerd runtime.

Start and Enable Docker Service

After the installation is complete, start the Docker service and enable it to start automatically on system boot:

sudo systemctl start docker
sudo systemctl enable docker

These commands will start the Docker daemon and ensure that it starts automatically whenever your system boots up.

Step 3: Install Docker Compose

Now that Docker is installed, let’s proceed with installing Docker Compose. Follow these steps:

Download Docker Compose Binary

Docker Compose is a single binary file that you can download from the official GitHub repository. Run the following command to download the latest version of Docker Compose:

sudo curl -L "https://github.com/docker/compose/releases/download/v2.12.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose

This command uses curl to download the Docker Compose binary for your specific operating system and architecture. It saves the binary in the /usr/local/bin directory.

Set Executable Permissions

To be able to run Docker Compose, you need to set the appropriate executable permissions on the downloaded binary. Use the following command:

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

This command grants execute permissions to the Docker Compose binary, allowing you to run it as a command.

Step 4: Verify Installation

After completing the installation steps, it’s crucial to verify that both Docker and Docker Compose are installed correctly.

Verify Docker Installation

To check the installed version of Docker, run the following command:

docker --version

You should see the Docker version displayed in the output, indicating a successful installation.

Verify Docker Compose Installation

Similarly, you can verify the installation of Docker Compose by checking its version:

docker-compose --version

If the installation was successful, you will see the version number of Docker Compose printed in the output.

Step 5: Basic Usage of Docker Compose

Now that you have Docker Compose installed, let’s explore a basic example of how to use it. We’ll create a simple web server using Nginx.

First, create a new directory for your project and navigate to it:

mkdir ~/compose-demo && cd ~/compose-demo

Next, create a docker-compose.yml file in the project directory with the following content:

echo "version: '3.7'
services:
  web:
    image: nginx:alpine
    ports:
      - '8000:80'" > docker-compose.yml

This docker-compose.yml file defines a single service named “web” that uses the nginx:alpine image. It maps port 8000 on the host to port 80 in the container.

To start the web server, run the following command:

docker-compose up -d

Docker Compose will download the necessary image (if not already present) and start the container in detached mode.

You can now access the web server by opening a web browser and visiting http://localhost:8000. You should see the default Nginx welcome page.

To stop the web server and remove the containers, run:

docker-compose down

Troubleshooting Common Issues

If you encounter any issues during the installation or usage of Docker Compose, here are a few troubleshooting tips:

• If you face permission-related errors, ensure that you have sudo privileges and prefix the commands with sudo.
• If Docker Compose commands are not recognized, double-check the installation steps and ensure that the binary is located in the /usr/local/bin directory.
• If containers fail to start or exhibit unexpected behavior, review the docker-compose.yml file for any syntax errors or misconfiguration.
• Check the Docker and Docker Compose logs for any error messages or warnings that can help identify the issue. You can use the docker logs and docker-compose logs commands for this purpose.