Added example systemd service for running the starter

CHANGELOG.md

@@ -1,5 +1,6 @@
 # Changes from version 0.10.4 to master
 
+- Added SystemD example. See `examples/systemd/README.md`.
 - Added `--log.dir` option to configure a custom directory to which all log files will be written.
 - It is no longer allowed to use `log.file` as a passthrough option.
 - Added `--starter.host` option, to bind the HTTP server to a specific network interface instead of the default `0.0.0.0`.

examples/systemd/README.md

@@ -0,0 +1,27 @@
+# Run ArangoDB Starter with SystemD
+
+This example shows how you can run the ArangoDB starter in a systemd service.
+
+The example will run the starter as user `arangodb` in group `arangodb`.
+It requires an environment variable file called `/etc/arangodb.env`
+with the following variables.
+
+```text
+STARTERENDPOINTS=<comma seperated list of endpoints of all starters (for --starter.join)>
+CLUSTERSECRET=<JWT secret used by the cluster>
+CLUSTERSECRETPATH=<full path of file containing the JWT secret used by the cluster>
+```
+
+To use this service, do the following on every machine on which the starter should run:
+
+- Create the `/etc/arangodb.env` environment file as specified above.
+- Copy the `arangodb.service` file to `/etc/systemd/system/arangodb.service`.
+- Trigger a systemd reload using `sudo systemctl daemon-reload`.
+- Enable the service using `sudo systemctl enable arangodb.service`.
+- Start the service using `sudo systemctl start arangodb.service`.
+
+Once started, you can view the logs of the starter using:
+
+```bash
+sudo journalctl -flu arangodb.service
+```

examples/systemd/arangodb.service

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+[Unit]
+Description=Run the ArangoDB Starter 
+After=network.target
+
+[Service]
+Restart=on-failure
+User=arangodb
+Group=arangodb
+EnvironmentFile=/etc/arangodb.env
+Environment=DATADIR=/var/lib/arangodb/cluster
+ExecStartPre=/usr/bin/sh -c "mkdir -p $(dirname $CLUSTERSECRETPATH)"
+ExecStartPre=/usr/bin/sh -c "mkdir -p ${DATADIR}"
+ExecStartPre=/usr/bin/sh -c "echo ${CLUSTERSECRET} > ${CLUSTERSECRETPATH}"
+ExecStart=/usr/bin/arangodb \
+    --starter.data-dir=${DATADIR} \
+    --starter.join=${STARTERENDPOINTS} \
+    --server.storage-engine=rocksdb \
+    --auth.jwt-secret=${CLUSTERSECRETPATH} \
+    --all.log.level=info --all.log.output=+
+TimeoutStopSec=60
+
+[Install]
+WantedBy=multi-user.target