fix: validate smtp smarthost and smtp from fields

SMTP smarthost and SMTP from are required
fields which needs to be specified at
either global or at receiver level.

This change will make sure reconciliation fails
if there is empty at both levels.

Related-to #6003

Signed-off-by: Jayapriya Pai <slashpai9@gmail.com>

pkg/alertmanager/amcfg.go

@@ -258,6 +258,13 @@ func (cb *configBuilder) initializeFromAlertmanagerConfig(ctx context.Context, g
 	}
 	globalAlertmanagerConfig.Global = global
 
+	// This is need to check required fields are set either at global or receiver level at later step.
+	if global != nil {
+		cb.cfg = &alertmanagerConfig{
+			Global: global,
+		}
+	}
+
 	// Add inhibitRules to globalAlertmanagerConfig.InhibitRules without enforce namespace
 	for _, inhibitRule := range amConfig.Spec.InhibitRules {
 		globalAlertmanagerConfig.InhibitRules = append(globalAlertmanagerConfig.InhibitRules, cb.convertInhibitRule(&inhibitRule))
@@ -1048,6 +1055,18 @@ func (cb *configBuilder) convertEmailConfig(ctx context.Context, in monitoringv1
 		RequireTLS:    in.RequireTLS,
 	}
 
+	if in.Smarthost == "" {
+		if cb.cfg.Global == nil || cb.cfg.Global.SMTPSmarthost.Host == "" {
+			return nil, fmt.Errorf("SMTP smarthost is a mandatory field, it is neither specified at global config nor at receiver level")
+		}
+	}
+
+	if in.From == "" {
+		if cb.cfg.Global == nil || cb.cfg.Global.SMTPFrom == "" {
+			return nil, fmt.Errorf("SMTP from is a mandatory field, it is neither specified at global config nor at receiver level")
+		}
+	}
+
 	if in.Smarthost != "" {
 		out.Smarthost.Host, out.Smarthost.Port, _ = net.SplitHostPort(in.Smarthost)
 	}

pkg/alertmanager/amcfg_test.go

@@ -1019,6 +1019,7 @@ func TestGenerateConfig(t *testing.T) {
 		matcherStrategy monitoringv1.AlertmanagerConfigMatcherStrategy
 		amConfigs       map[string]*monitoringv1alpha1.AlertmanagerConfig
 		golden          string
+		expectedError   bool
 	}
 	version24, err := semver.ParseTolerant("v0.24.0")
 	require.NoError(t, err)
@@ -2364,6 +2365,157 @@ func TestGenerateConfig(t *testing.T) {
 			},
 			golden: "CR_with_MSTeams_Receiver_Partial_Conf.golden",
 		},
+		{
+			name:      "CR with EmailConfig with Required Fields specified at Receiver level",
+			amVersion: &version26,
+			kclient:   fake.NewSimpleClientset(),
+			baseConfig: alertmanagerConfig{
+				Route: &route{
+					Receiver: "null",
+				},
+				Receivers: []*receiver{{Name: "null"}},
+			},
+			amConfigs: map[string]*monitoringv1alpha1.AlertmanagerConfig{
+				"mynamespace": {
+					ObjectMeta: metav1.ObjectMeta{
+						Name:      "myamc",
+						Namespace: "mynamespace",
+					},
+					Spec: monitoringv1alpha1.AlertmanagerConfigSpec{
+						Route: &monitoringv1alpha1.Route{
+							Receiver: "test",
+						},
+						Receivers: []monitoringv1alpha1.Receiver{
+							{
+								Name: "test",
+								EmailConfigs: []monitoringv1alpha1.EmailConfig{
+									{
+										Smarthost: "example.com:25",
+										From:      "admin@example.com",
+										To:        "customers@example.com",
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			golden: "CR_with_EmailConfig_Receiver_Conf.golden",
+		},
+		{
+			name:      "CR with EmailConfig Missing SmartHost Field",
+			amVersion: &version26,
+			kclient:   fake.NewSimpleClientset(),
+			baseConfig: alertmanagerConfig{
+				Route: &route{
+					Receiver: "null",
+				},
+				Receivers: []*receiver{{Name: "null"}},
+			},
+			amConfigs: map[string]*monitoringv1alpha1.AlertmanagerConfig{
+				"mynamespace": {
+					ObjectMeta: metav1.ObjectMeta{
+						Name:      "myamc",
+						Namespace: "mynamespace",
+					},
+					Spec: monitoringv1alpha1.AlertmanagerConfigSpec{
+						Route: &monitoringv1alpha1.Route{
+							Receiver: "test",
+						},
+						Receivers: []monitoringv1alpha1.Receiver{
+							{
+								Name: "test",
+								EmailConfigs: []monitoringv1alpha1.EmailConfig{
+									{
+										From: "admin@example.com",
+										To:   "customers@example.com",
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			expectedError: true,
+		},
+		{
+			name:      "CR with EmailConfig Missing SMTP From Field",
+			amVersion: &version26,
+			kclient:   fake.NewSimpleClientset(),
+			baseConfig: alertmanagerConfig{
+				Route: &route{
+					Receiver: "null",
+				},
+				Receivers: []*receiver{{Name: "null"}},
+			},
+			amConfigs: map[string]*monitoringv1alpha1.AlertmanagerConfig{
+				"mynamespace": {
+					ObjectMeta: metav1.ObjectMeta{
+						Name:      "myamc",
+						Namespace: "mynamespace",
+					},
+					Spec: monitoringv1alpha1.AlertmanagerConfigSpec{
+						Route: &monitoringv1alpha1.Route{
+							Receiver: "test",
+						},
+						Receivers: []monitoringv1alpha1.Receiver{
+							{
+								Name: "test",
+								EmailConfigs: []monitoringv1alpha1.EmailConfig{
+									{
+										From: "admin@example.com",
+										To:   "customers@example.com",
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			expectedError: true,
+		},
+		{
+			name:      "CR with EmailConfig Missing Required Fields from Receiver level but specified at Global level",
+			amVersion: &version26,
+			kclient:   fake.NewSimpleClientset(),
+			baseConfig: alertmanagerConfig{
+				Global: &globalConfig{
+					SMTPSmarthost: config.HostPort{
+						Host: "smtp.example.org",
+						Port: "587",
+					},
+					SMTPFrom: "admin@globaltest.com",
+				},
+				Route: &route{
+					Receiver: "null",
+				},
+				Receivers: []*receiver{{Name: "null"}},
+			},
+			amConfigs: map[string]*monitoringv1alpha1.AlertmanagerConfig{
+				"mynamespace": {
+					ObjectMeta: metav1.ObjectMeta{
+						Name:      "myamc",
+						Namespace: "mynamespace",
+					},
+					Spec: monitoringv1alpha1.AlertmanagerConfigSpec{
+						Route: &monitoringv1alpha1.Route{
+							Receiver: "test",
+						},
+						Receivers: []monitoringv1alpha1.Receiver{
+							{
+								Name: "test",
+								EmailConfigs: []monitoringv1alpha1.EmailConfig{
+									{
+										To: "customers@example.com",
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			golden: "CR_with_EmailConfig_Receiver_Global_Defaults_Conf.golden",
+		},
 	}
 
 	logger := newNopLogger(t)
@@ -2380,6 +2532,10 @@ func TestGenerateConfig(t *testing.T) {
 			cb := newConfigBuilder(logger, *tc.amVersion, store, tc.matcherStrategy)
 			cb.cfg = &tc.baseConfig
 
+			if tc.expectedError {
+				require.Error(t, cb.addAlertmanagerConfigs(context.Background(), tc.amConfigs))
+				return
+			}
 			require.NoError(t, cb.addAlertmanagerConfigs(context.Background(), tc.amConfigs))
 
 			cfgBytes, err := cb.marshalJSON()

pkg/alertmanager/testdata/CR_with_EmailConfig_Receiver_Conf.golden

@@ -0,0 +1,15 @@
+route:
+  receiver: "null"
+  routes:
+  - receiver: mynamespace/myamc/test
+    matchers:
+    - namespace="mynamespace"
+    continue: true
+receivers:
+- name: "null"
+- name: mynamespace/myamc/test
+  email_configs:
+  - to: customers@example.com
+    from: admin@example.com
+    smarthost: example.com:25
+templates: []

pkg/alertmanager/testdata/CR_with_EmailConfig_Receiver_Global_Defaults_Conf.golden

@@ -0,0 +1,16 @@
+global:
+  smtp_from: admin@globaltest.com
+  smtp_smarthost: smtp.example.org:587
+route:
+  receiver: "null"
+  routes:
+  - receiver: mynamespace/myamc/test
+    matchers:
+    - namespace="mynamespace"
+    continue: true
+receivers:
+- name: "null"
+- name: mynamespace/myamc/test
+  email_configs:
+  - to: customers@example.com
+templates: []

test/e2e/alertmanager_test.go

@@ -1083,7 +1083,9 @@ func testAlertmanagerConfigCRD(t *testing.T) {
 					SendResolved: func(b bool) *bool {
 						return &b
 					}(true),
-					To: "test@example.com",
+					Smarthost: "example.com:25",
+					From:      "admin@example.com",
+					To:        "test@example.com",
 					AuthPassword: &v1.SecretKeySelector{
 						LocalObjectReference: v1.LocalObjectReference{
 							Name: testingSecret,
@@ -1496,6 +1498,8 @@ receivers:
   email_configs:
   - send_resolved: true
     to: test@example.com
+    from: admin@example.com
+    smarthost: example.com:25
     auth_password: 1234abc
     auth_secret: 1234abc
     headers: