Cannot connect to the Docker daemon at unix:///var/run/dock…

This error occurs when the Docker client is unable to connect to the Docker daemon, which is necessary for executing Docker commands. This can happen if the Docker service is not running or if the user does not have the necessary permissions to access the Docker socket.

The root cause is typically that the Docker daemon is not running, or the current user does not have permission to access the Docker socket file located at /var/run/docker.sock. Without the daemon running or proper permissions, the client cannot establish a connection.

To resolve this issue, first check if the Docker service is running by executing 'systemctl status docker'. If it is not running, start it with 'sudo systemctl start docker'. Additionally, ensure your user is added to the 'docker' group to avoid permission issues by running 'sudo usermod -aG docker $USER' and then logging out and back in.