How to start a Docker instance on Ubuntu start up?

Starting a Docker Instance on Ubuntu at Startup

Introduction

Docker is a popular containerization platform that allows developers to package, ship, and run applications in containers. Ubuntu is a popular Linux distribution that is widely used for server and desktop environments. In this article, we will show you how to start a Docker instance on Ubuntu at startup.

Prerequisites

Before we begin, make sure you have the following prerequisites:

• Ubuntu 18.04 or later: Docker is supported on Ubuntu 18.04 and later versions.
• Docker Engine: You need to have Docker Engine installed on your system. You can download it from the official Docker website.
• Docker Compose: Docker Compose is a tool that allows you to define and run multi-container Docker applications. You can download it from the official Docker website.

Step 1: Install Docker

To start a Docker instance on Ubuntu at startup, you need to install Docker Engine. Here’s how:

• Open a terminal and run the following command:

  sudo apt update
  
  sudo apt install docker.io

• Once the installation is complete, run the following command to start Docker Engine:

  sudo systemctl start docker

• You can verify that Docker Engine is running by running the following command:

  sudo systemctl status docker

Step 2: Create a Docker User and Group

To use Docker, you need to create a Docker user and group. Here’s how:

• Open a terminal and run the following command:

  sudo useradd -m docker

• This will create a new user called docker with a home directory.
• Run the following command to create a new group called docker:

  sudo groupadd docker

• You can verify that the user and group are created by running the following command:

  sudo getent group docker

Step 3: Create a Docker User and Group with Docker Compose

To use Docker Compose, you need to create a Docker user and group with the following commands:

• Open a terminal and run the following command:

  sudo useradd -m docker-compose

• This will create a new user called docker-compose with a home directory.
• Run the following command to create a new group called docker-compose:

  sudo groupadd docker-compose

• You can verify that the user and group are created by running the following command:

  sudo getent group docker-compose

Step 4: Configure Docker to Use the New User and Group

To configure Docker to use the new user and group, you need to edit the docker-compose.conf file. Here’s how:

• Open a text editor and create a new file called docker-compose.conf in the /etc/docker/ directory:

  sudo nano /etc/docker/daemon.json

• Add the following lines to the file:

  {
  
  "newUser": "docker",
  
  "newGroup": "docker"
  
  }

• Save and close the file.

Step 5: Restart Docker Engine

To apply the changes, you need to restart Docker Engine. Here’s how:

• Open a terminal and run the following command:

  sudo systemctl restart docker

• You can verify that Docker Engine is restarted by running the following command:

  sudo systemctl status docker

Step 6: Verify Docker Instance at Startup

To verify that Docker instance is started at startup, you can use the following command:

• Open a terminal and run the following command:

  sudo systemctl status docker

• You should see a message indicating that Docker Engine is running.

Troubleshooting

If you encounter any issues while starting Docker at startup, here are some troubleshooting steps:

• Check the Docker logs by running the following command:

  sudo docker logs

• Check the Docker status by running the following command:

  sudo docker status

• Check the system logs by running the following command:

  sudo journalctl

• Check the Docker configuration by running the following command:

  sudo docker-compose -f /etc/docker/daemon.json -f /etc/docker/daemon.json

• Check the system configuration by running the following command:

  sudo systemctl status docker

Conclusion

Starting a Docker instance on Ubuntu at startup is a straightforward process that requires installing Docker Engine, creating a Docker user and group, configuring Docker to use the new user and group, and restarting Docker Engine. By following these steps, you can ensure that your Ubuntu system starts with a fully functional Docker environment.