Permission denied errors when running Docker commands.
`docker compose` commands fail with permission errors. Cannot run Docker commands without sudo.
User is not in the docker group.
Add user to docker group.
Steps:
1. Add user to docker group: `sudo usermod -aG docker $USER` 2. Log out and log back in (or restart terminal) 3. Verify: `groups $USER` should show `docker`
Add all users who need Docker access to the docker group during initial server setup.