docs: add systemd instructions (#276)

Add how to run soft-serve using systemd instructions

README.md

@@ -113,6 +113,12 @@ full privileges.
 Using this environment variable, Soft Serve will create a new `admin` user that
 has full privileges. You can rename and change the user settings later.
 
+Check out [Systemd][systemd] on how to run Soft Serve as a service using
+Systemd. Soft Serve packages in our Apt/Yum repositories come with Systemd
+service units.
+
+[systemd]: https://github.com/charmbracelet/soft-serve/blob/main/systemd.md
+
 ### Server Settings
 
 Once you start the server for the first time, the settings will be in
@@ -188,11 +194,9 @@ http:
 stats:
   # The address on which the stats server will listen.
   listen_addr: ":23233"
-
 # Additional admin keys.
 #initial_admin_keys:
 #  - "ssh-rsa AAAAB3NzaC1yc2..."
-
 ```
 
 You can also use environment variables, to override these settings. All server

systemd.md

@@ -0,0 +1,99 @@
+# Running Soft Serve as a Systemd Service
+
+Most Linux OSes use Systemd as an init system and service management. You can
+use Systemd to manage Soft Serve as a service on your host machine.
+
+Our Soft Serve deb/rpm packages come with Systemd service files pre-packaged.
+You can install `soft-serve` from our Apt/Yum repositories. Follow the
+[installation instructions](https://github.com/charmbracelet/soft-serve#installation) for
+more information.
+
+## Writing a Systemd Service File
+
+> **Note** you can skip this section if you are using our deb/rpm packages or
+> installed Soft Serve from our Apt/Yum repositories.
+
+Start by writing a Systemd service file to define how your Soft Serve server
+should start.
+
+First, we need to specify where the data should live for our server. Here I
+will be choosing `/var/local/lib/soft-serve` to store the server's data. Soft
+Serve will look for this path in the `SOFT_SERVE_DATA_PATH` environment
+variable.
+
+Make sure this directory exists before proceeding.
+
+```sh
+sudo mkdir -p /var/local/lib/soft-serve
+```
+
+We will also create a `/etc/soft-serve.conf` file for any extra server settings that we want to override.
+
+```conf
+# Config defined here will override the config in /var/local/lib/soft-serve/config.yaml
+# Keys defined in `SOFT_SERVE_INITIAL_ADMIN_KEYS` will be merged with
+# the `initial_admin_keys` from /var/local/lib/soft-serve/config.yaml.
+#
+#SOFT_SERVE_GIT_LISTEN_ADDR=:9418
+#SOFT_SERVE_HTTP_LISTEN_ADDR=:23232
+#SOFT_SERVE_SSH_LISTEN_ADDR=:23231
+#SOFT_SERVE_SSH_KEY_PATH=ssh/soft_serve_host_ed25519
+#SOFT_SERVE_INITIAL_ADMIN_KEYS='ssh-ed25519 AAAAC3NzaC1lZDI1...'
+```
+
+> **Note** Soft Serve stores its server configuration and settings in
+> `config.yaml` under its _data path_ directory specified using
+> `SOFT_SERVE_DATA_PATH` environment variable.
+
+Now, let's write a new `/etc/systemd/system/soft-serve.service` Systemd service file:
+
+```conf
+[Unit]
+Description=Soft Serve git server 🍦
+Documentation=https://github.com/charmbracelet/soft-serve
+Requires=network-online.target
+After=network-online.target
+
+[Service]
+Type=simple
+Restart=always
+RestartSec=1
+ExecStart=/usr/bin/soft serve
+Environment=SOFT_SERVE_DATA_PATH=/var/local/lib/soft-serve
+EnvironmentFile=-/etc/soft-serve.conf
+WorkingDirectory=/var/local/lib/soft-serve
+
+[Install]
+WantedBy=multi-user.target
+```
+
+Great, we now have a Systemd service file for Soft Serve. The settings defined
+here may vary depending on your specific setup. This assumes that you want to
+run Soft Serve as `root`. For more information on Systemd service files, refer
+to
+[systemd.service](https://www.freedesktop.org/software/systemd/man/systemd.service.html)
+
+## Start Soft Serve on boot
+
+Now that we have our Soft Serve Systemd service file in-place, let's go ahead
+and enable and start Soft Serve to run on-boot.
+
+```sh
+# Reload systemd daemon
+sudo systemctl daemon-reload
+# Enable Soft Serve to start on-boot
+sudo systemctl enable soft-serve.service
+# Start Soft Serve now!!
+sudo systemctl start soft-serve.service
+```
+
+You can monitor the server logs using `journalctl -u soft-serve.service`. Use
+`-f` to _tail_ and follow the logs as they get written.
+
+***
+
+Part of [Charm](https://charm.sh).
+
+<a href="https://charm.sh/"><img alt="The Charm logo" src="https://stuff.charm.sh/charm-badge-unrounded.jpg" width="400"></a>
+
+Charm热爱开源 • Charm loves open source