2 dockers installed on ubuntu server

2 min read 10-03-2025

This guide provides a detailed walkthrough of setting up and managing two separate Docker installations on a single Ubuntu server. This might be necessary for various reasons, such as isolating environments for different projects, testing, or managing distinct Docker versions. We'll cover the installation process, configuration, and management of these separate instances.

Why Run Two Docker Installations?

Before diving into the technical details, let's explore the reasons why you might need two separate Docker installations on your Ubuntu server:

Isolation: Separate installations provide strong isolation between your Docker environments. This prevents conflicts between applications, versions, or configurations. If one Docker instance encounters issues, it won't affect the other.
Version Control: Maintaining different Docker versions allows for testing compatibility with older applications or experimenting with new features without impacting your production environment.
Project Separation: Separating projects into individual Docker installations improves organization and simplifies management. This is particularly useful for developers working on multiple projects simultaneously.
Security: By segmenting your Docker environments, you can enhance the security of your server. A compromised container in one instance is less likely to affect the other.

Method 1: Using Different User Accounts

The simplest method involves installing Docker twice, once for each user. This creates completely separate environments.

Step 1: Create a New User

First, create a new user account on your Ubuntu server:

sudo adduser dockeruser2
sudo usermod -aG docker dockeruser2

This creates a user named dockeruser2 and adds them to the docker group, granting Docker access.

Step 2: Install Docker for the Second User

sudo apt update
sudo apt install docker.io
sudo systemctl start docker
sudo systemctl enable docker

You now have two independent Docker installations; one for your default user and one for dockeruser2. Manage each separately, using sudo if necessary for system-level commands.

Method 2: Installing Docker in Different Directories (Advanced)

This method is more complex but provides greater isolation. It involves installing Docker in separate directories, ensuring no file conflicts. This requires manual configuration and is generally not recommended unless absolutely necessary.

Step 1: Download Docker

Download the Docker installation package manually into your desired directory (e.g., /opt/docker2).

Step 2: Manual Installation

This process involves extracting the package, configuring it manually, and setting up environment variables to avoid conflicts with the existing Docker installation. This is highly advanced and requires in-depth knowledge of Docker's internal workings. It is strongly advised to consult the official Docker documentation for guidance on this intricate process.

Managing Multiple Docker Installations

Regardless of the chosen method, managing your multiple Docker installations requires careful attention. Remember to use sudo when necessary, especially when interacting with system-level services like systemctl. Consider using Docker Compose to manage multi-container applications within each instance for better organization.

Troubleshooting

If you encounter problems, check the following:

Permissions: Ensure that your user has the necessary permissions to run Docker commands.
Conflicts: Make sure there are no conflicting configuration files or environment variables.
Daemon Status: Verify that the Docker daemon is running for both installations using sudo systemctl status docker.

Conclusion

Running two Docker installations on a single Ubuntu server provides significant advantages for managing multiple projects, isolating environments, and testing different versions. While the first method (using different user accounts) is the recommended approach for simplicity, understanding the complexities of Method 2 is crucial for more advanced use cases. Always prioritize security and carefully manage your configurations to avoid conflicts. Remember to consult the official Docker documentation for the most up-to-date information and best practices.