add postinst script

Author: heldner

debian/fmd.service

@@ -4,8 +4,8 @@ Documentation=https://gitlab.com/Nulide/findmydeviceserver
 After=network.target
 
 [Service]
+User=fmd
 CapabilityBoundingSet=CAP_NET_BIND_SERVICE
-DynamicUser=true
 ExecStart=/usr/bin/fmd serve --config /etc/findmydeviceserver/config.yml --web-dir /usr/lib/fmd-web --db-dir /var/cache/fmd-db
 KillMode=process
 Restart=always

debian/postinst

@@ -0,0 +1,14 @@
+#! /bin/sh
+set -e
+
+FMDUSER=fmd
+
+if [ "$1" = 'configure' ] && [ -z "$DPKG_ROOT" ] && ! getent passwd $FMDUSER >/dev/null; then
+    # add unprivileged user for the findmydeviceserver
+    adduser --force-badname --system --home /nonexistent  \
+        --no-create-home --quiet $FMDUSER || true
+fi
+
+if [ $(stat -c %U /var/cache/fmd-db) != "$FMDUSER" ]; then
+    chown -R /var/cache/fmd-db
+fi