upstream-zulip/docs/development/setup/install-docker.md

##### 2. Create the `docker` group and add yourself to it:

```console
$ sudo groupadd docker
$ sudo usermod -aG docker $USER
```

You will need to log out and log back in (or reboot) for this change to take effect.
If it worked, you will see `docker` in your list of groups:

```console
$ groups | grep docker
YOURUSERNAME adm cdrom sudo dip plugdev lpadmin sambashare docker
```

##### 3. Make sure the Docker daemon is running

Docker runs as a background service (daemon), which must be running for Docker commands to work.
You can check using the following:

```console
$ systemctl status docker
● docker.service - Docker Application Container Engine
   Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2019-07-15 23:20:46 IST; 18min ago
```

If the service is not running, you'll see `Active: inactive (dead)` on
the second line, and will need to enable and start the Docker service
using the following:

```console
$ sudo systemctl unmask docker
$ sudo systemctl enable docker
$ sudo systemctl start docker
```