gbproxy: add example .service

Change-Id: Ic8144777a77efce4bad44abf6c6abde12fc5149c
Related: SYS#3610
diff --git a/openbsc/contrib/systemd/osmo-gbproxy.service b/openbsc/contrib/systemd/osmo-gbproxy.service
new file mode 100644
index 0000000..a0b7829
--- /dev/null
+++ b/openbsc/contrib/systemd/osmo-gbproxy.service
@@ -0,0 +1,12 @@
+[Unit]
+Description=Osmocom Gb proxy
+
+[Service]
+Type=simple
+ExecStart=/usr/bin/osmo-gbproxy -c /etc/osmocom/osmo-gbproxy.cfg
+Restart=always
+RestartSec=2
+RestartPreventExitStatus=1
+
+[Install]
+WantedBy=multi-user.target