Alerting: Add X-Remote-Alertmanager header to the remote AM client (#94913)

Author: santihernandezc

pkg/services/ngalert/remote/alertmanager_test.go

@@ -125,8 +125,11 @@ func TestNewAlertmanager(t *testing.T) {
 }
 
 func TestApplyConfig(t *testing.T) {
+	const tenantID = "test"
 	// errorHandler returns an error response for the readiness check and state sync.
 	errorHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		require.Equal(t, tenantID, r.Header.Get(client.MimirTenantHeader))
+		require.Equal(t, "true", r.Header.Get(client.RemoteAlertmanagerHeader))
 		w.Header().Add("content-type", "application/json")
 		w.WriteHeader(http.StatusInternalServerError)
 		require.NoError(t, json.NewEncoder(w).Encode(map[string]string{"status": "error"}))
@@ -135,6 +138,8 @@ func TestApplyConfig(t *testing.T) {
 	var configSent client.UserGrafanaConfig
 	var lastConfigSync, lastStateSync time.Time
 	okHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		require.Equal(t, tenantID, r.Header.Get(client.MimirTenantHeader))
+		require.Equal(t, "true", r.Header.Get(client.RemoteAlertmanagerHeader))
 		if r.Method == http.MethodPost {
 			if strings.Contains(r.URL.Path, "/config") {
 				require.NoError(t, json.NewDecoder(r.Body).Decode(&configSent))
@@ -166,7 +171,7 @@ func TestApplyConfig(t *testing.T) {
 	server := httptest.NewServer(errorHandler)
 	cfg := AlertmanagerConfig{
 		OrgID:         1,
-		TenantID:      "test",
+		TenantID:      tenantID,
 		URL:           server.URL,
 		DefaultConfig: defaultGrafanaConfig,
 		PromoteConfig: true,
@@ -228,6 +233,7 @@ func TestApplyConfig(t *testing.T) {
 }
 
 func TestCompareAndSendConfiguration(t *testing.T) {
+	const tenantID = "test"
 	cfgWithSecret, err := notifier.Load([]byte(testGrafanaConfigWithSecret))
 	require.NoError(t, err)
 	testValue := []byte("test")
@@ -240,6 +246,8 @@ func TestCompareAndSendConfiguration(t *testing.T) {
 
 	var got string
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		require.Equal(t, tenantID, r.Header.Get(client.MimirTenantHeader))
+		require.Equal(t, "true", r.Header.Get(client.RemoteAlertmanagerHeader))
 		w.Header().Add("content-type", "application/json")
 
 		b, err := io.ReadAll(r.Body)
@@ -255,7 +263,7 @@ func TestCompareAndSendConfiguration(t *testing.T) {
 	m := metrics.NewRemoteAlertmanagerMetrics(prometheus.NewRegistry())
 	cfg := AlertmanagerConfig{
 		OrgID:         1,
-		TenantID:      "test",
+		TenantID:      tenantID,
 		URL:           server.URL,
 		DefaultConfig: defaultGrafanaConfig,
 	}
@@ -336,6 +344,7 @@ func TestCompareAndSendConfiguration(t *testing.T) {
 }
 
 func Test_TestReceiversDecryptsSecureSettings(t *testing.T) {
+	const tenantID = "test"
 	const testKey = "test-key"
 	const testValue = "test-value"
 	decryptFn := func(_ context.Context, payload []byte) ([]byte, error) {
@@ -347,6 +356,8 @@ func Test_TestReceiversDecryptsSecureSettings(t *testing.T) {
 
 	var got apimodels.TestReceiversConfigBodyParams
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		require.Equal(t, tenantID, r.Header.Get(client.MimirTenantHeader))
+		require.Equal(t, "true", r.Header.Get(client.RemoteAlertmanagerHeader))
 		w.Header().Add("Content-Type", "application/json")
 		require.NoError(t, json.NewDecoder(r.Body).Decode(&got))
 		require.NoError(t, r.Body.Close())
@@ -358,7 +369,7 @@ func Test_TestReceiversDecryptsSecureSettings(t *testing.T) {
 	m := metrics.NewRemoteAlertmanagerMetrics(prometheus.NewRegistry())
 	cfg := AlertmanagerConfig{
 		OrgID:         1,
-		TenantID:      "test",
+		TenantID:      tenantID,
 		URL:           server.URL,
 		DefaultConfig: defaultGrafanaConfig,
 	}

pkg/services/ngalert/remote/client/mimir_auth_round_tripper.go

@@ -4,7 +4,10 @@ import (
 	"net/http"
 )
 
-const mimirTenantHeader = "X-Scope-OrgID"
+const (
+	MimirTenantHeader        = "X-Scope-OrgID"
+	RemoteAlertmanagerHeader = "X-Remote-Alertmanager"
+)
 
 type MimirAuthRoundTripper struct {
 	TenantID string
@@ -16,8 +19,9 @@ type MimirAuthRoundTripper struct {
 // It adds an `X-Scope-OrgID` header with the TenantID if only provided with a tenantID or sets HTTP Basic Authentication if both
 // a tenantID and a password are provided.
 func (r *MimirAuthRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	req.Header.Set(RemoteAlertmanagerHeader, "true")
 	if r.TenantID != "" && r.Password == "" {
-		req.Header.Set(mimirTenantHeader, r.TenantID)
+		req.Header.Set(MimirTenantHeader, r.TenantID)
 	}
 
 	if r.TenantID != "" && r.Password != "" {