Support multiple daemon instances with systemd in Debian.

debian/systemd@.service

@@ -0,0 +1,31 @@
+[Unit]
+Description=dnsmasq (%i) - A lightweight DHCP and caching DNS server
+Requires=network.target
+Wants=nss-lookup.target
+Before=nss-lookup.target
+After=network.target
+
+[Service]
+Type=forking
+PIDFile=/run/dnsmasq/dnsmasq.%i.pid
+
+# Test the config file and refuse starting if it is not valid.
+ExecStartPre=/etc/init.d/dnsmasq checkconfig "%i"
+
+# We run dnsmasq via the /etc/init.d/dnsmasq script which acts as a
+# wrapper picking up extra configuration files and then execs dnsmasq
+# itself, when called with the "systemd-exec" function.
+ExecStart=/etc/init.d/dnsmasq systemd-exec "%i"
+
+# The systemd-*-resolvconf functions configure (and deconfigure)
+# resolvconf to work with the dnsmasq DNS server. They're called like
+# this to get correct error handling (ie don't start-resolvconf if the
+# dnsmasq daemon fails to start).
+ExecStartPost=/etc/init.d/dnsmasq systemd-start-resolvconf "%i"
+ExecStop=/etc/init.d/dnsmasq systemd-stop-resolvconf "%i"
+
+
+ExecReload=/bin/kill -HUP $MAINPID
+
+[Install]
+WantedBy=multi-user.target