Docker Compose is an essential tool for defining and running multi-container Docker applications. It allows you to configure and manage your application’s services with a single YAML file, simplifying complex setups. If you’re using Ubuntu 20.04, installing Docker Compose is straightforward and adds immense flexibility to your Docker workflows.
In this guide, we will walk you through the steps to install Docker Compose on Ubuntu 20.04. Whether you’re new to Docker or an experienced user, you’ll find these instructions easy to follow and understand.
What is Docker Compose?
Docker Compose is a tool that enables you to define and manage multi-container Docker applications. With Docker Compose, you can:
- Define your entire application stack (including databases, caching services, and more) in a single
docker-compose.ymlfile. - Use a simple command to spin up multiple containers and start the application.
- Easily scale services and maintain complex application architectures.
For example, if you want to run a web app alongside a database, Docker Compose can start both containers and link them together, all with minimal configuration.
Benefits of Using Docker Compose
- Simplified Multi-Container Management: Manage multiple containers as a single entity, making complex setups easy to deploy.
- Reproducibility: Ensure the same configuration across different environments—whether it’s local development, testing, or production.
- Easy Scaling: Scale individual services up or down without affecting other containers.
- Reduced Complexity: The YAML configuration file simplifies the process of defining containerized applications.
Now that we know why Docker Compose is essential, let’s look at the steps to install it on Ubuntu 20.04.
Prerequisites
Before you begin, ensure that you have the following:
- Ubuntu 20.04 system: Docker Compose is supported on Ubuntu 20.04 and earlier versions.
- Docker Engine Installed: Docker Compose requires Docker to be installed on your system.
Once Docker is installed, you’re good to go!
Step-by-Step Guide to Install Docker Compose on Ubuntu 20.04
Step 1: Update Your System
First, you should update your system to ensure that all existing packages are up-to-date. This helps to avoid issues during installation.
Open your terminal and run:
sudo apt update && sudo apt upgrade -y
This will update both the package lists and the installed packages on your system.
Step 2: Install Dependencies
Docker Compose requires curl to download its installation script. If curl is not already installed, you can install it by running:
sudo apt install curl -y
Step 3: Download Docker Compose
Next, you need to download the Docker Compose binary from the official Docker GitHub repository. Run the following command to get the latest stable release of Docker Compose:
sudo curl -L "https://github.com/docker/compose/releases/download/$(curl -s https://api.github.com/repos/docker/compose/releases/latest | jq -r .tag_name)/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
Here’s a breakdown of the command:
curl -L: This fetches the Docker Compose binary from the Docker repository.jq: This tool helps parse the latest release tag from Docker Compose’s GitHub page./usr/local/bin/docker-compose: This is the target directory where thedocker-composebinary will be saved.
Step 4: Set Permissions
Once the binary is downloaded, you need to set the executable permission for the Docker Compose binary. Run the following command:
sudo chmod +x /usr/local/bin/docker-compose
This command grants execute permissions to the docker-compose binary, allowing it to run on your system.
Step 5: Verify the Installation
To confirm that Docker Compose was installed successfully, run:
docker-compose --version
If everything went well, you should see the version of Docker Compose you installed, for example:
docker-compose version 1.29.2, build 5becea4c
This means Docker Compose is now ready to use on your Ubuntu 20.04 system!
Using Docker Compose on Ubuntu 20.04
Once Docker Compose is installed, you can start using it to define and manage multi-container applications. Docker Compose uses a configuration file named docker-compose.yml to define the services, networks, and volumes used by your application.
Example: A Simple Docker Compose File
Here’s a basic example of a docker-compose.yml file that runs a simple web app and a MySQL database container:
version: "3"
services:
web:
image: nginx:latest
ports:
- "8080:80"
db:
image: mysql:latest
environment:
MYSQL_ROOT_PASSWORD: example
In this file:
- The
webservice uses the latestnginximage and binds port 8080 on the host to port 80 in the container. - The
dbservice uses the latestmysqlimage, and it sets a root password for MySQL via environment variables.
Step 1: Create the docker-compose.yml File
First, create a directory for your project and navigate to it:
mkdir my-docker-compose-project
cd my-docker-compose-project
Then, create the docker-compose.yml file:
nano docker-compose.yml
Paste the contents of the example configuration and save the file.
Step 2: Run Docker Compose
Now that the docker-compose.yml file is set up, you can start the containers defined in the file by running:
docker-compose up
This command will pull the required images and start the services as defined in your docker-compose.yml file.
Step 3: Scale Services
If you need to scale a service, you can do so easily with Docker Compose. For example, to run 3 instances of the web service, use the following command:
docker-compose up --scale web=3
This will create 3 containers running the nginx image, load-balanced by Docker Compose.
Step 4: Stopping and Removing Containers
To stop and remove the containers defined by Docker Compose, use:
docker-compose down
This will stop the containers and remove the associated networks. If you want to remove volumes as well, add the -v flag:
docker-compose down -v
Troubleshooting Common Issues
Error: docker-compose: command not found
If you encounter the error docker-compose: command not found, it may indicate that the binary is not in the correct directory or didn’t install properly. To resolve this, try re-running the installation steps and ensure that /usr/local/bin is in your $PATH.
Permission Denied
If you get a “permission denied” error when trying to execute Docker Compose, ensure that the binary has executable permissions:
sudo chmod +x /usr/local/bin/docker-compose
Updating Docker Compose
To update Docker Compose to the latest version, simply run the same curl command you used for installation, which will fetch the latest release. Before doing so, you can remove the older binary with:
sudo rm /usr/local/bin/docker-compose
Then, run the installation steps again to download the latest version.
Conclusion
In this guide, we’ve shown you how to install Docker Compose on Ubuntu 20.04 and start managing multi-container applications with ease. Docker Compose simplifies the process of managing complex applications and makes scaling and deploying microservices a breeze.
With Docker Compose installed and working on your system, you can start defining and deploying your applications more efficiently, saving time and improving productivity.
Next Steps
- Explore Docker Compose documentation: Learn about advanced Compose features like networks, volumes, and environment variables.
- Experiment with your own
docker-compose.ymlconfigurations: Define multi-container applications based on your project needs. - Consider using Docker Swarm or Kubernetes: If you’re scaling your applications to production, consider using orchestrators like Docker Swarm or Kubernetes.
