Linux post-installation steps for Docker Engine
These optional post-installation procedures describe how to configure your Linux host machine to work better with Docker.
The Docker daemon binds to a Unix socket, not a TCP port. By default it's the
root user that owns the Unix socket, and other users can only access it using
sudo. The Docker daemon always runs as the
If you don't want to preface the
docker command with
sudo, create a Unix
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 for you to
manually create the group.
dockergroup grants root-level privileges to the user. For details on how this impacts security in your system, see Docker Daemon Attack Surface.
To run Docker without root privileges, see Run the Docker daemon as a non-root user (Rootless mode).
To create the
docker group and add your user:
$ sudo groupadd docker
Add your user to the
$ 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.
You can also run the following command to activate the changes to groups:
$ newgrp docker
Verify that you can run
$ 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.
If you initially ran Docker CLI commands using
sudobefore adding your user to the
dockergroup, you may see the following error:
WARNING: Error loading config file: /home/user/.docker/config.json - stat /home/user/.docker/config.json: permission denied
This error indicates that the permission settings for the
~/.docker/directory are incorrect, due to having used the
To fix this problem, either remove the
~/.docker/directory (it's recreated automatically, but any custom settings are lost), or change its ownership and permissions using the following commands:
$ sudo chown "$USER":"$USER" /home/"$USER"/.docker -R $ sudo chmod g+rwx "$HOME/.docker" -R
Many modern Linux distributions use systemd to manage which services start when the system boots. On Debian and Ubuntu, the Docker service starts on boot by default. To automatically start Docker and containerd on boot for other Linux distributions using systemd, run the following commands:
$ sudo systemctl enable docker.service $ sudo systemctl enable containerd.service
To stop this behavior, use
$ sudo systemctl disable docker.service $ sudo systemctl disable containerd.service
If you need to add an HTTP proxy, set a different directory or partition for the Docker runtime files, or make other customizations, see customize your systemd Docker daemon options.
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 expand in size, leading to
potential exhaustion of disk resources.
To avoid issues with overusing disk for log data, consider one of the following options:
- Configure the
json-filelogging driver to turn on log rotation.
- Use an alternative logging driver such as the "local" logging driver that performs log rotation by default.
- Use a logging driver that sends logs to a remote logging aggregator.