vmalertmanager: fixed ignore templates

docs/CHANGELOG.md

@@ -19,6 +19,7 @@ aliases:
 * BUGFIX: [converter](https://docs.victoriametrics.com/operator/integrations/prometheus/#objects-conversion): disable all prometheus controllers if CRD group was not found. See [#2838](https://github.com/VictoriaMetrics/helm-charts/issues/2838).
 * BUGFIX: [vmdistributed](https://docs.victoriametrics.com/operator/resources/vmdistributed/): change default load balancing policy for write requests from `first_available` to `least_loaded`. This should allow to evenly distribute write load across all VMAgents.
 * BUGFIX: [vmalertmanagerconfig](https://docs.victoriametrics.com/operator/resources/vmalertmanagerconfig/): fix previously ignored negative values in VMAlertmanagerConfig. See [#2132](https://github.com/VictoriaMetrics/operator/issues/2132).
+* BUGFIX: [vmalertmanager](https://docs.victoriametrics.com/operator/resources/vmalertmanager/): fixed ignored alertmanager template if it has no discovered VMAlertmanagerconfig CRs or tracing config defined. See [#2121](https://github.com/VictoriaMetrics/operator/issues/2121).
 
 ## [v0.69.0](https://github.com/VictoriaMetrics/operator/releases/tag/v0.69.0)
 **Release date:** 22 April 2026

internal/controller/operator/factory/vmalertmanager/config.go

@@ -105,7 +105,7 @@ type parsedObjects struct {
 }
 
 func (pos *parsedObjects) buildConfig(cr *vmv1beta1.VMAlertmanager, data []byte, ac *build.AssetsCache) ([]byte, error) {
-	if len(pos.configs.All()) == 0 && cr.Spec.TracingConfig == nil {
+	if len(pos.configs.All()) == 0 && cr.Spec.TracingConfig == nil && len(cr.Spec.Templates) == 0 {
 		return data, nil
 	}
 	var baseCfg amConfig

internal/controller/operator/factory/vmalertmanager/config_test.go

@@ -62,6 +62,48 @@ func TestBuildConfig(t *testing.T) {
 		assert.Equal(t, o.want, string(data))
 	}
 
+	// templates only
+	f(opts{
+		cr: &vmv1beta1.VMAlertmanager{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      "test",
+				Namespace: "default",
+			},
+			Spec: vmv1beta1.VMAlertmanagerSpec{
+				EnforcedNamespaceLabel:  "alert-namespace",
+				ConfigNamespaceSelector: &metav1.LabelSelector{},
+				Templates: []vmv1beta1.ConfigMapKeyReference{
+					{LocalObjectReference: corev1.LocalObjectReference{Name: "test-am"}, Key: "test_1.tmpl"},
+				},
+			},
+		},
+		baseCfg: []byte(`global:
+ time_out: 1min
+ smtp_smarthost: some:443
+`),
+		predefinedObjects: []runtime.Object{
+			&corev1.Secret{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "ca",
+					Namespace: "default",
+				},
+				Data: map[string][]byte{
+					"key": []byte("value"),
+				},
+			},
+		},
+		want: `global:
+  smtp_smarthost: some:443
+  time_out: 1min
+route:
+  receiver: blackhole
+receivers:
+- name: blackhole
+templates:
+- /etc/vm/templates/test-am/test_1.tmpl
+`,
+	})
+
 	// tracing without discovered objects
 	f(opts{
 		cr: &vmv1beta1.VMAlertmanager{