Reduce amount of firewall status updates through monitor controller.

Currently updates happen as often as the firewall-controller updates the monitor. Most of the time this is completely irrelevant and just producing noise.

controllers/monitor/reconcile.go

@@ -6,6 +6,8 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
 	v2 "github.com/metal-stack/firewall-controller-manager/api/v2"
 	"github.com/metal-stack/firewall-controller-manager/controllers"
 	"github.com/metal-stack/firewall-controller-manager/controllers/firewall"
@@ -43,8 +45,14 @@ func (c *controller) updateFirewallStatus(r *controllers.Ctx[*v2.FirewallMonitor
 		return nil, fmt.Errorf("associated firewall of monitor not found: %w", err)
 	}
 
+	old := fw.DeepCopy()
+
 	firewall.SetFirewallStatusFromMonitor(fw, r.Target)
 
+	if !significantFirewallStatusChange(old.Status, fw.Status) {
+		return fw, nil
+	}
+
 	err = c.c.GetSeedClient().Status().Update(r.Ctx, fw)
 	if err != nil {
 		return nil, fmt.Errorf("unable to update firewall status: %w", err)
@@ -128,3 +136,19 @@ func findCorrespondingSet(ctx context.Context, c client.Client, fw *v2.Firewall)
 
 	return set, nil
 }
+
+func significantFirewallStatusChange(o, n v2.FirewallStatus) bool {
+	// only consider relevant fields, we only care for controller status updates in this controller
+	// (to immediately see when the controller has connected)
+	// after that the firewall controller syncs the status every 2 minutes anyway
+
+	if o.ControllerStatus == nil && n.ControllerStatus != nil {
+		return true
+	}
+
+	if !cmp.Equal(o.Conditions, n.Conditions, cmpopts.IgnoreFields(v2.Condition{}, "Message", "LastUpdateTime", "LastTransitionTime")) {
+		return true
+	}
+
+	return false
+}

controllers/monitor/reconcile_test.go

@@ -0,0 +1,72 @@
+package monitor
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/google/go-cmp/cmp"
+	v2 "github.com/metal-stack/firewall-controller-manager/api/v2"
+	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+func Test_significantFirewallStatusChange(t *testing.T) {
+	now := time.Now()
+
+	tests := []struct {
+		name string
+		o    v2.FirewallStatus
+		n    v2.FirewallStatus
+		want bool
+	}{
+		{
+			name: "controller registers",
+			o: v2.FirewallStatus{
+				ControllerStatus: nil,
+			},
+			n: v2.FirewallStatus{
+				ControllerStatus: &v2.ControllerConnection{
+					ActualVersion: "1.2.3",
+					Updated:       v1.NewTime(now),
+				},
+			},
+			want: true,
+		},
+		{
+			name: "conditions not really changed",
+			o: v2.FirewallStatus{
+				Conditions: v2.Conditions{
+					v2.NewCondition(v2.FirewallControllerSeedConnected, v2.ConditionTrue, "Connected", fmt.Sprintf("Controller reconciled firewall at %s.", now.Add(-1*time.Minute))),
+				},
+			},
+			n: v2.FirewallStatus{
+				Conditions: v2.Conditions{
+					v2.NewCondition(v2.FirewallControllerSeedConnected, v2.ConditionTrue, "Connected", fmt.Sprintf("Controller reconciled firewall at %s.", now.Add(1*time.Minute))),
+				},
+			},
+			want: false,
+		},
+		{
+			name: "controller reconnects",
+			o: v2.FirewallStatus{
+				Conditions: v2.Conditions{
+					v2.NewCondition(v2.FirewallControllerConnected, v2.ConditionFalse, "StoppedReconciling", fmt.Sprintf("Controller has stopped reconciling since %s to shoot.", now)),
+				},
+			},
+			n: v2.FirewallStatus{
+				Conditions: v2.Conditions{
+					v2.NewCondition(v2.FirewallControllerConnected, v2.ConditionTrue, "Connected", fmt.Sprintf("Controller reconciled shoot at %s.", now)),
+				},
+			},
+			want: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := significantFirewallStatusChange(tt.o, tt.n)
+			if diff := cmp.Diff(tt.want, got); diff != "" {
+				t.Errorf("diff (+got -want):\n %s", diff)
+			}
+		})
+	}
+}