Merge pull request 'Sort render inputs so config is deterministic (stop restart loop)' (#11) from benvin/deterministic-render into main

Reviewed-on: #11

internal/bind/render.go

@@ -28,9 +28,28 @@ type RenderInput struct {
 // cluster. Both variants are shipped in the ConfigMap; the entrypoint selects
 // one based on the pod ordinal.
 func RenderNamedConf(in RenderInput) (primary string, secondary string) {
+	// client.List returns cache-ordered (non-deterministic) results, so sort
+	// every input slice before rendering. Otherwise the rendered config
+	// reshuffles between reconciles, churning the ConfigMap — and with the
+	// pod-template config hash that means an endless rolling restart.
+	sortInput(&in)
 	return render(in, true), render(in, false)
 }
 
+// sortInput orders every list rendered into named.conf deterministically.
+func sortInput(in *RenderInput) {
+	sort.Slice(in.ACLs, func(i, j int) bool { return in.ACLs[i].Name < in.ACLs[j].Name })
+	sort.Slice(in.Views, func(i, j int) bool {
+		if in.Views[i].Spec.Order != in.Views[j].Spec.Order {
+			return in.Views[i].Spec.Order < in.Views[j].Spec.Order
+		}
+		return in.Views[i].Name < in.Views[j].Name
+	})
+	sort.Slice(in.Forwards, func(i, j int) bool { return in.Forwards[i].Spec.ZoneName < in.Forwards[j].Spec.ZoneName })
+	sort.Slice(in.Policies, func(i, j int) bool { return in.Policies[i].Spec.ZoneName < in.Policies[j].Spec.ZoneName })
+	sort.Slice(in.DNSSECPolicies, func(i, j int) bool { return in.DNSSECPolicies[i].Name < in.DNSSECPolicies[j].Name })
+}
+
 func render(in RenderInput, isPrimary bool) string {
 	c := in.Cluster
 	var b strings.Builder

internal/bind/render_test.go

@@ -146,3 +146,34 @@ func TestCatalogHashStable(t *testing.T) {
 		t.Fatalf("expected 40-char hex sha1, got %d: %s", len(h1), h1)
 	}
 }
+
+func TestRenderDeterministicWithShuffledForwards(t *testing.T) {
+	// client.List order is non-deterministic; the render must not depend on
+	// input order, or the ConfigMap churns and (with the config hash) the
+	// StatefulSet rolls forever.
+	mkFwd := func(zone, fwd string) bindv1alpha1.BindZone {
+		return bindv1alpha1.BindZone{
+			ObjectMeta: metav1.ObjectMeta{Name: zone},
+			Spec: bindv1alpha1.BindZoneSpec{
+				ClusterRef: "r", Type: bindv1alpha1.ZoneForward,
+				ZoneName: zone, Forwarders: []string{fwd},
+			},
+		}
+	}
+	base := RenderInput{Cluster: newCluster(bindv1alpha1.ModeResolver)}
+	orderA := base
+	orderA.Forwards = []bindv1alpha1.BindZone{
+		mkFwd("unkin.net", "198.18.200.6"), mkFwd("consul", "198.18.19.14"),
+		mkFwd("k8s.syd1.au.unkin.net", "198.18.200.8"), mkFwd("13.18.198.in-addr.arpa", "198.18.200.6"),
+	}
+	orderB := base
+	orderB.Forwards = []bindv1alpha1.BindZone{
+		mkFwd("13.18.198.in-addr.arpa", "198.18.200.6"), mkFwd("k8s.syd1.au.unkin.net", "198.18.200.8"),
+		mkFwd("consul", "198.18.19.14"), mkFwd("unkin.net", "198.18.200.6"),
+	}
+	pa, _ := RenderNamedConf(orderA)
+	pb, _ := RenderNamedConf(orderB)
+	if pa != pb {
+		t.Fatalf("render must be independent of forward-zone input order:\n--- A ---\n%s\n--- B ---\n%s", pa, pb)
+	}
+}