fix(collectors): make sure config map rendering is stable

In particular with respect to the inherently non-deterministic ordering
of the list of monitoring resources.

fixes ENG-3946

internal/backendconnection/otelcolresources/desired_state.go

@@ -6,6 +6,7 @@ package otelcolresources
 import (
 	"fmt"
 	"path/filepath"
+	"slices"
 	"strings"
 
 	appsv1 "k8s.io/api/apps/v1"
@@ -197,6 +198,11 @@ func assembleDesiredState(
 	resourceSpecs *OTelColResourceSpecs,
 	forDeletion bool,
 ) ([]clientObject, error) {
+	// Make sure the resulting objects (in particular the config maps) are do not depend on the (potentially non-stable)
+	// sort order of the input slices.
+	slices.Sort(monitoredNamespaces)
+	slices.Sort(namespacesWithPrometheusScraping)
+
 	var desiredState []clientObject
 	desiredState = append(desiredState, addCommonMetadata(assembleServiceAccountForDaemonSet(config)))
 	daemonSetCollectorConfigMap, err := assembleDaemonSetCollectorConfigMap(

internal/backendconnection/otelcolresources/desired_state_test.go

@@ -9,6 +9,8 @@ import (
 
 	appsv1 "k8s.io/api/apps/v1"
 	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/utils/ptr"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 
 	dash0v1alpha1 "github.com/dash0hq/dash0-operator/api/dash0monitoring/v1alpha1"
@@ -321,6 +323,81 @@ var _ = Describe("The desired state of the OpenTelemetry Collector resources", f
 		Expect(selfMonitoringConfiguration.Export.Grpc).To(BeNil())
 		Expect(selfMonitoringConfiguration.Export.Http).To(BeNil())
 	})
+
+	It("rendered objects must be stable", func() {
+		mr1 := dash0v1alpha1.Dash0Monitoring{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      MonitoringResourceName,
+				Namespace: "namespace-1",
+			},
+			Spec: dash0v1alpha1.Dash0MonitoringSpec{
+				PrometheusScrapingEnabled: ptr.To(true),
+			},
+		}
+		mr2 := dash0v1alpha1.Dash0Monitoring{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      MonitoringResourceName,
+				Namespace: "namespace-2",
+			},
+			Spec: dash0v1alpha1.Dash0MonitoringSpec{
+				PrometheusScrapingEnabled: ptr.To(true),
+			},
+		}
+		mr3 := dash0v1alpha1.Dash0Monitoring{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      MonitoringResourceName,
+				Namespace: "namespace-3",
+			},
+			Spec: dash0v1alpha1.Dash0MonitoringSpec{
+				PrometheusScrapingEnabled: ptr.To(false),
+			},
+		}
+		mr4 := dash0v1alpha1.Dash0Monitoring{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      MonitoringResourceName,
+				Namespace: "namespace-4",
+			},
+			Spec: dash0v1alpha1.Dash0MonitoringSpec{
+				PrometheusScrapingEnabled: ptr.To(false),
+			},
+		}
+
+		desiredState1, err := assembleDesiredStateForUpsert(&oTelColConfig{
+			Namespace:  namespace,
+			NamePrefix: namePrefix,
+			Export:     Dash0ExportWithEndpointAndToken(),
+			Images:     TestImages,
+		}, []dash0v1alpha1.Dash0Monitoring{mr1, mr2, mr3, mr4}, &DefaultOTelColResourceSpecs)
+		Expect(err).NotTo(HaveOccurred())
+		desiredState2, err := assembleDesiredStateForUpsert(&oTelColConfig{
+			Namespace:  namespace,
+			NamePrefix: namePrefix,
+			Export:     Dash0ExportWithEndpointAndToken(),
+			Images:     TestImages,
+		}, []dash0v1alpha1.Dash0Monitoring{mr3, mr4, mr1, mr2}, &DefaultOTelColResourceSpecs)
+		Expect(err).NotTo(HaveOccurred())
+		desiredState3, err := assembleDesiredStateForUpsert(&oTelColConfig{
+			Namespace:  namespace,
+			NamePrefix: namePrefix,
+			Export:     Dash0ExportWithEndpointAndToken(),
+			Images:     TestImages,
+		}, []dash0v1alpha1.Dash0Monitoring{mr4, mr3, mr2, mr1}, &DefaultOTelColResourceSpecs)
+		Expect(err).NotTo(HaveOccurred())
+		desiredState4, err := assembleDesiredStateForUpsert(&oTelColConfig{
+			Namespace:  namespace,
+			NamePrefix: namePrefix,
+			Export:     Dash0ExportWithEndpointAndToken(),
+			Images:     TestImages,
+		}, []dash0v1alpha1.Dash0Monitoring{mr3, mr1, mr4, mr2}, &DefaultOTelColResourceSpecs)
+		Expect(err).NotTo(HaveOccurred())
+
+		Expect(reflect.DeepEqual(desiredState1, desiredState2)).To(BeTrue())
+		Expect(reflect.DeepEqual(desiredState1, desiredState3)).To(BeTrue())
+		Expect(reflect.DeepEqual(desiredState1, desiredState4)).To(BeTrue())
+		Expect(reflect.DeepEqual(desiredState2, desiredState3)).To(BeTrue())
+		Expect(reflect.DeepEqual(desiredState2, desiredState4)).To(BeTrue())
+		Expect(reflect.DeepEqual(desiredState3, desiredState4)).To(BeTrue())
+	})
 })
 
 func getConfigMap(desiredState []clientObject, name string) *corev1.ConfigMap {

test/util/monitoring_resource.go

@@ -27,7 +27,6 @@ var (
 		Namespace: TestNamespaceName,
 		Name:      MonitoringResourceName,
 	}
-
 	MonitoringResourceDefaultObjectMeta = metav1.ObjectMeta{
 		Name:      MonitoringResourceName,
 		Namespace: TestNamespaceName,