add a test for adding dynamic backends to directors at runtime, and

for deleting backends that have been added to directors

src/tests/z00004.vtc

+varnishtest "add and remove backends from directors at runtime"
+
+server s1 {} -start
+
+server s2 {
+	rxreq
+	txresp
+} -start
+
+varnish v1 -vcl {
+	import backend_dyn from "${vmod_topbuild}/src/.libs/libvmod_backend_dyn.so";
+	import ${vmod_directors};
+	backend dummy { .host="${bad_ip}"; }
+
+	sub vcl_init {
+		if (!backend_dyn.create(name="be", host="${s1_addr}",
+		   			port="${s1_port}")) {
+			return(fail);
+		}
+                new rr = directors.round_robin();
+                rr.add_backend(backend_dyn.by_name("be"));
+	}
+
+	sub vcl_recv {
+		if (req.method == "DELETE") {
+			if (backend_dyn.delete(backend_dyn.by_name("be"))) {
+				return(synth(204));
+			}
+			else {
+				return(synth(500));
+			}
+		}
+		if (req.method == "PUT") {
+			if (!backend_dyn.create(name="s2", host="${s2_addr}",
+			   			port="${s2_port}")) {
+				return(synth(500));
+			}
+			rr.add_backend(backend_dyn.by_name("s2"));
+			return(synth(204));
+		}
+		set req.backend_hint = rr.backend();
+		return(pass);
+	}
+
+	sub vcl_backend_response {
+		set beresp.http.X-Backend = beresp.backend.name;
+	}
+} -start
+
+client c1 {
+	txreq -req "PUT"
+	rxresp
+	expect resp.status == 204
+	txreq -req "DELETE"
+	rxresp
+	expect resp.status == 204
+	txreq
+	rxresp
+	expect resp.status == 200
+	expect resp.http.X-Backend == "s2"
+} -run
+
+server s2 -start
+varnish v1 -stop
+varnish v1 -start
+
+client c1 {
+	txreq -req "DELETE"
+	rxresp
+	expect resp.status == 204
+	txreq
+	rxresp
+	expect resp.status == 503
+	txreq -req "PUT"
+	rxresp
+	expect resp.status == 204
+	txreq
+	rxresp
+	expect resp.status == 200
+	expect resp.http.X-Backend == "s2"
+} -run