Manage Docker as a Non-Root User¶

The Docker daemon binds to a Unix socket, not a TCP port. By default, the root user owns the Unix socket, and other users can only access it using sudo. The Docker daemon always runs as the root user.

If you don't want to preface the docker command with sudo, create a Unix group called docker and add users to it. When the Docker daemon starts, it creates a Unix socket accessible by members of the docker group. On some Linux distributions, the system automatically creates this group when installing Docker Engine using a package manager. In that case, there is no need to manually create the group.

Warning
The docker group grants root-level privileges to the user. For details on how this impacts security in your system, see Docker Daemon Attack Surface.

Note: To run Docker without root privileges, see Run the Docker daemon as a non-root user (Rootless mode).

Steps to Create the Docker Group and Add Your User¶

Create the docker group:
```
sudo groupadd docker
```
Add your user to the docker group:
```
sudo usermod -aG docker $USER
```
Log out and log back in so that your group membership is re-evaluated.
- If you're running Linux in a virtual machine, it may be necessary to restart the virtual machine for changes to take effect.
- Alternatively, run the following command to activate the changes to groups:
```
newgrp docker
```
Verify that you can run Docker commands without sudo:
```
docker run hello-world
```
This command downloads a test image and runs it in a container. When the container runs, it prints a message and exits.

Fixing Permission Errors¶

If you initially ran Docker CLI commands using sudo before adding your user to the docker group, you may encounter the following error:

WARNING: Error loading config file: /home/user/.docker/config.json -
stat /home/user/.docker/config.json: permission denied

To fix this issue, either:

Remove the ~/.docker/ directory (it will be recreated automatically, but any custom settings will be lost):
```
rm -rf ~/.docker
```

Or change its ownership and permissions:

sudo chown "$USER":"$USER" /home/"$USER"/.docker -R
sudo chmod g+rwx "$HOME/.docker" -R

Configure Docker to Start on Boot with systemd¶

Many modern Linux distributions use systemd to manage services at boot. On Debian and Ubuntu, the Docker service starts on boot by default. To enable this behavior on other Linux distributions using systemd, run:

sudo systemctl enable docker.service
sudo systemctl enable containerd.service

To disable this behavior, use:

sudo systemctl disable docker.service
sudo systemctl disable containerd.service

You can also use systemd unit files to configure the Docker service on startup. For example, you can add an HTTP proxy, set a different directory for Docker runtime files, or apply other customizations. See Configure the daemon to use a proxy for more details.

Configure Default Logging Driver¶

Docker provides logging drivers for collecting and viewing log data from all containers running on a host. The default logging driver, json-file, writes log data to JSON-formatted files on the host filesystem. Over time, these log files can grow in size, potentially exhausting disk resources.

To avoid disk overuse, consider one of the following options:

Configure the json-file logging driver to enable log rotation.
Use an alternative logging driver, such as the local logging driver, which performs log rotation by default.
Use a logging driver that sends logs to a remote logging aggregator.

Next Steps¶

Explore the Docker workshop to learn how to build an image and run it as a containerized application.