Fix ForwardBackend filters initialization in routegroup

dataclients/kubernetes/routegroup.go

@@ -298,6 +298,7 @@ func applyBackend(ctx *routeGroupContext, backend *definitions.SkipperBackend, r
 	case eskip.ForwardBackend:
 		r.Backend = ctx.forwardBackendURL
 		r.BackendType = eskip.NetworkBackend
+		r.Filters = []*eskip.Filter{}
 	}
 
 	if ctx.backendNameTracingTag {

dataclients/kubernetes/testdata/routegroups/backends/forward-with-filters.eskip

@@ -0,0 +1,8 @@
+kube_rg____example_org__catchall__0_0:
+	Host("^(example[.]org[.]?(:[0-9]+)?)$")
+	-> <shunt>;
+
+kube_rg__default__myapp__all__0_0:
+	Host("^(example[.]org[.]?(:[0-9]+)?)$")
+	&& PathSubtree("/")
+	-> "http://forward.example";

dataclients/kubernetes/testdata/routegroups/backends/forward-with-filters.kube

@@ -0,0 +1 @@
+forward-backend-url: http://forward.example

dataclients/kubernetes/testdata/routegroups/backends/forward-with-filters.yaml

@@ -0,0 +1,16 @@
+apiVersion: zalando.org/v1
+kind: RouteGroup
+metadata:
+  name: myapp
+spec:
+  hosts:
+    - example.org
+  backends:
+    - name: fwd
+      type: forward
+  routes:
+    - pathSubtree: /
+      filters:
+        - status(200)
+      backends:
+        - backendName: fwd

routesrv/routesrv_test.go

@@ -651,6 +651,37 @@ func TestRoutesWithForwardBackend(t *testing.T) {
 	wantHTTPCode(t, w, http.StatusOK)
 }
 
+func TestRoutesWithForwardBackendFiltersDropped(t *testing.T) {
+	defer tl.Reset()
+	ks, _ := newKubeServer(t, loadKubeYAML(t, "testdata/forward-backend-with-filter.yaml"))
+	ks.Start()
+	defer ks.Close()
+	rs := newRouteServerWithOptions(t, skipper.Options{
+		SourcePollTimeout: pollInterval,
+		Kubernetes:        true,
+		KubernetesURL:     ks.URL,
+		ForwardBackendURL: "http://forward.example",
+	})
+
+	rs.StartUpdates()
+	defer rs.StopUpdates()
+
+	if err := tl.WaitFor(routesrv.LogRoutesInitialized, waitTimeout); err != nil {
+		t.Fatalf("routes not initialized: %v", err)
+	}
+	w := getRoutes(rs)
+
+	want := parseEskipFixture(t, "testdata/forward-backend-with-filter.eskip")
+	got, err := eskip.Parse(w.Body.String())
+	if err != nil {
+		t.Fatalf("served routes are not valid eskip: %s", w.Body)
+	}
+	if !eskip.EqLists(got, want) {
+		t.Errorf("expected to receive route without filters: %s", cmp.Diff(got, want))
+	}
+	wantHTTPCode(t, w, http.StatusOK)
+}
+
 func TestESkipBytesHandlerWithCorrectEtag(t *testing.T) {
 	defer tl.Reset()
 	ks, _ := newKubeServer(t, loadKubeYAML(t, "testdata/lb-target-multi.yaml"))

routesrv/testdata/forward-backend-with-filter.eskip

@@ -0,0 +1 @@
+kube_rg__default__my_test__all__0_0: PathSubtree("/") -> "http://forward.example";

routesrv/testdata/forward-backend-with-filter.yaml

@@ -0,0 +1,14 @@
+apiVersion: zalando.org/v1
+kind: RouteGroup
+metadata:
+  name: my-test
+spec:
+  backends:
+    - name: fwd
+      type: forward
+  routes:
+    - pathSubtree: /
+      filters:
+        - status(200)
+      backends:
+        - backendName: fwd