From 42c001dd1495c5ee1feea283558ac8e6e58fb722 Mon Sep 17 00:00:00 2001
From: Thibault Jamet <tjamet@users.noreply.github.com>
Date: Fri, 13 Sep 2024 19:43:53 +0200
Subject: [PATCH] fix(appset): Fix perpetual appset reconciliation (#19822)
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Golang maps do not guarantee the order of the application resources
from the applicationset which causes rapid sync activity for the applicationset
as the objects and hence their resourceVersions are updated after each reconcile loop.

This then triggers reconciliation of all objects watching the
ApplicationSet.

In order to prevent this behaviour, ensure that the ApplicationSet
reconciler provides an idempotent list of resources, ensuring objects
are not updated.

Fixes: #19757

Signed-off-by: Thibault Jamet <thibault.jamet@adevinta.com>
Signed-off-by: Fabián Sellés <fabian.selles@adevinta.com>
Co-authored-by: Fabian Selles <fabian.sellesrosa@gmail.com>
Co-authored-by: Ariadna Rouco <ariadna.rouco@adevinta.com>
---
 .../controllers/applicationset_controller.go  |  4 +
 .../applicationset_controller_test.go         | 99 +++++++++++++++++++
 2 files changed, 103 insertions(+)

diff --git a/applicationset/controllers/applicationset_controller.go b/applicationset/controllers/applicationset_controller.go
index 70fa60e97a0f6..d3911f1e0c7c4 100644
--- a/applicationset/controllers/applicationset_controller.go
+++ b/applicationset/controllers/applicationset_controller.go
@@ -18,6 +18,7 @@ import (
 	"context"
 	"fmt"
 	"reflect"
+	"sort"
 	"strings"
 	"time"
 
@@ -1295,6 +1296,9 @@ func (r *ApplicationSetReconciler) updateResourcesStatus(ctx context.Context, lo
 	for _, status := range statusMap {
 		statuses = append(statuses, status)
 	}
+	sort.Slice(statuses, func(i, j int) bool {
+		return statuses[i].Name < statuses[j].Name
+	})
 	appset.Status.Resources = statuses
 	// DefaultRetry will retry 5 times with a backoff factor of 1, jitter of 0.1 and a duration of 10ms
 	err := retry.RetryOnConflict(retry.DefaultRetry, func() error {
diff --git a/applicationset/controllers/applicationset_controller_test.go b/applicationset/controllers/applicationset_controller_test.go
index d5813d5f114a8..02608175245b4 100644
--- a/applicationset/controllers/applicationset_controller_test.go
+++ b/applicationset/controllers/applicationset_controller_test.go
@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"reflect"
+	"strconv"
 	"strings"
 	"testing"
 	"time"
@@ -6137,6 +6138,104 @@ func TestUpdateResourceStatus(t *testing.T) {
 	}
 }
 
+func generateNAppResourceStatuses(n int) []v1alpha1.ResourceStatus {
+	var r []v1alpha1.ResourceStatus
+	for i := 0; i < n; i++ {
+		r = append(r, v1alpha1.ResourceStatus{
+			Name:   "app" + strconv.Itoa(i),
+			Status: v1alpha1.SyncStatusCodeSynced,
+			Health: &v1alpha1.HealthStatus{
+				Status:  health.HealthStatusHealthy,
+				Message: "OK",
+			},
+		},
+		)
+	}
+	return r
+}
+
+func generateNHealthyApps(n int) []v1alpha1.Application {
+	var r []v1alpha1.Application
+	for i := 0; i < n; i++ {
+		r = append(r, v1alpha1.Application{
+			ObjectMeta: metav1.ObjectMeta{
+				Name: "app" + strconv.Itoa(i),
+			},
+			Status: v1alpha1.ApplicationStatus{
+				Sync: v1alpha1.SyncStatus{
+					Status: v1alpha1.SyncStatusCodeSynced,
+				},
+				Health: v1alpha1.HealthStatus{
+					Status:  health.HealthStatusHealthy,
+					Message: "OK",
+				},
+			},
+		})
+	}
+	return r
+}
+
+func TestResourceStatusAreOrdered(t *testing.T) {
+	scheme := runtime.NewScheme()
+	err := v1alpha1.AddToScheme(scheme)
+	require.NoError(t, err)
+
+	err = v1alpha1.AddToScheme(scheme)
+	require.NoError(t, err)
+	for _, cc := range []struct {
+		name              string
+		appSet            v1alpha1.ApplicationSet
+		apps              []v1alpha1.Application
+		expectedResources []v1alpha1.ResourceStatus
+	}{
+		{
+			name: "Ensures AppSet is always ordered",
+			appSet: v1alpha1.ApplicationSet{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "name",
+					Namespace: "argocd",
+				},
+				Status: v1alpha1.ApplicationSetStatus{
+					Resources: []v1alpha1.ResourceStatus{},
+				},
+			},
+			apps:              generateNHealthyApps(10),
+			expectedResources: generateNAppResourceStatuses(10),
+		},
+	} {
+		t.Run(cc.name, func(t *testing.T) {
+			kubeclientset := kubefake.NewSimpleClientset([]runtime.Object{}...)
+			argoDBMock := dbmocks.ArgoDB{}
+			argoObjs := []runtime.Object{}
+
+			client := fake.NewClientBuilder().WithScheme(scheme).WithStatusSubresource(&cc.appSet).WithObjects(&cc.appSet).Build()
+			metrics := appsetmetrics.NewFakeAppsetMetrics(client)
+
+			r := ApplicationSetReconciler{
+				Client:           client,
+				Scheme:           scheme,
+				Recorder:         record.NewFakeRecorder(1),
+				Generators:       map[string]generators.Generator{},
+				ArgoDB:           &argoDBMock,
+				ArgoAppClientset: appclientset.NewSimpleClientset(argoObjs...),
+				KubeClientset:    kubeclientset,
+				Metrics:          metrics,
+			}
+
+			err := r.updateResourcesStatus(context.TODO(), log.NewEntry(log.StandardLogger()), &cc.appSet, cc.apps)
+			require.NoError(t, err, "expected no errors, but errors occurred")
+
+			err = r.updateResourcesStatus(context.TODO(), log.NewEntry(log.StandardLogger()), &cc.appSet, cc.apps)
+			require.NoError(t, err, "expected no errors, but errors occurred")
+
+			err = r.updateResourcesStatus(context.TODO(), log.NewEntry(log.StandardLogger()), &cc.appSet, cc.apps)
+			require.NoError(t, err, "expected no errors, but errors occurred")
+
+			assert.Equal(t, cc.expectedResources, cc.appSet.Status.Resources, "expected resources did not match actual")
+		})
+	}
+}
+
 func TestOwnsHandler(t *testing.T) {
 	// progressive syncs do not affect create, delete, or generic
 	ownsHandler := getOwnsHandlerPredicates(true)