AzureMonitor: Add custom header support to Azure Monitor (#60269)

* Add integration test for Azure Monitor

- Add Azure Monitor to datasource types
- Update instance creation to correctly set HTTP client options
- Combine custom azure headers and custom grafana headers on HTTP client creation
- Update HTTP client tests

* Test custom azure headers

pkg/tsdb/azuremonitor/azuremonitor.go

@@ -68,9 +68,9 @@ type Service struct {
 	tracer          tracing.Tracer
 }
 
-func getDatasourceService(cfg *setting.Cfg, clientProvider *httpclient.Provider, dsInfo types.DatasourceInfo, routeName string) (types.DatasourceService, error) {
+func getDatasourceService(cfg *setting.Cfg, clientProvider *httpclient.Provider, dsInfo types.DatasourceInfo, routeName string, httpClientOptions httpclient.Options) (types.DatasourceService, error) {
 	route := dsInfo.Routes[routeName]
-	client, err := newHTTPClient(route, dsInfo, cfg, clientProvider)
+	client, err := newHTTPClient(route, dsInfo, cfg, clientProvider, httpClientOptions)
 	if err != nil {
 		return types.DatasourceService{}, err
 	}
@@ -86,13 +86,17 @@ func NewInstanceSettings(cfg *setting.Cfg, clientProvider *httpclient.Provider,
 		if err != nil {
 			return nil, fmt.Errorf("error reading settings: %w", err)
 		}
-
 		jsonDataObj := map[string]interface{}{}
 		err = json.Unmarshal(settings.JSONData, &jsonDataObj)
 		if err != nil {
 			return nil, fmt.Errorf("error reading settings: %w", err)
 		}
 
+		httpClientOpts, err := settings.HTTPClientOptions()
+		if err != nil {
+			return nil, fmt.Errorf("error getting http options: %w", err)
+		}
+
 		azMonitorSettings := types.AzureMonitorSettings{}
 		err = json.Unmarshal(settings.JSONData, &azMonitorSettings)
 		if err != nil {
@@ -126,7 +130,7 @@ func NewInstanceSettings(cfg *setting.Cfg, clientProvider *httpclient.Provider,
 		}
 
 		for routeName := range executors {
-			service, err := getDatasourceService(cfg, clientProvider, model, routeName)
+			service, err := getDatasourceService(cfg, clientProvider, model, routeName, httpClientOpts)
 			if err != nil {
 				return nil, err
 			}

pkg/tsdb/azuremonitor/httpclient.go

@@ -13,9 +13,9 @@ import (
 	"github.com/grafana/grafana/pkg/tsdb/azuremonitor/types"
 )
 
-func newHTTPClient(route types.AzRoute, model types.DatasourceInfo, cfg *setting.Cfg, clientProvider httpclient.Provider) (*http.Client, error) {
-	opts := sdkhttpclient.Options{
-		Headers: route.Headers,
+func newHTTPClient(route types.AzRoute, model types.DatasourceInfo, cfg *setting.Cfg, clientProvider httpclient.Provider, httpClientOptions sdkhttpclient.Options) (*http.Client, error) {
+	for header, value := range route.Headers {
+		httpClientOptions.Headers[header] = value
 	}
 
 	// Use Azure credentials if the route has OAuth scopes configured
@@ -23,8 +23,8 @@ func newHTTPClient(route types.AzRoute, model types.DatasourceInfo, cfg *setting
 		if cred, ok := model.Credentials.(*azcredentials.AzureClientSecretCredentials); ok && cred.ClientSecret == "" {
 			return nil, fmt.Errorf("unable to initialize HTTP Client: clientSecret not found")
 		}
-		azhttpclient.AddAzureAuthentication(&opts, cfg.Azure, model.Credentials, route.Scopes)
+		azhttpclient.AddAzureAuthentication(&httpClientOptions, cfg.Azure, model.Credentials, route.Scopes)
 	}
 
-	return clientProvider.New(opts)
+	return clientProvider.New(httpClientOptions)
 }

pkg/tsdb/azuremonitor/httpclient_test.go

@@ -28,7 +28,7 @@ func TestHttpClient_AzureCredentials(t *testing.T) {
 			Scopes: []string{"https://management.azure.com/.default"},
 		}
 
-		_, err := newHTTPClient(route, model, cfg, provider)
+		_, err := newHTTPClient(route, model, cfg, provider, sdkhttpclient.Options{})
 		require.NoError(t, err)
 
 		require.NotNil(t, provider.opts)
@@ -41,7 +41,7 @@ func TestHttpClient_AzureCredentials(t *testing.T) {
 			Scopes: []string{},
 		}
 
-		_, err := newHTTPClient(route, model, cfg, provider)
+		_, err := newHTTPClient(route, model, cfg, provider, sdkhttpclient.Options{})
 		require.NoError(t, err)
 
 		assert.NotNil(t, provider.opts)
@@ -50,6 +50,33 @@ func TestHttpClient_AzureCredentials(t *testing.T) {
 			assert.Len(t, provider.opts.Middlewares, 0)
 		}
 	})
+
+	t.Run("should combine custom azure and custom grafana headers", func(t *testing.T) {
+		route := types.AzRoute{
+			Headers: map[string]string{
+				"AzureHeader": "AzureValue",
+			},
+		}
+		opts := sdkhttpclient.Options{
+			Headers: map[string]string{
+				"GrafanaHeader": "GrafanaValue",
+			},
+		}
+
+		res := map[string]string{
+			"GrafanaHeader": "GrafanaValue",
+			"AzureHeader":   "AzureValue",
+		}
+		_, err := newHTTPClient(route, model, cfg, provider, opts)
+		require.NoError(t, err)
+
+		assert.NotNil(t, provider.opts)
+
+		if provider.opts.Headers != nil {
+			assert.Len(t, provider.opts.Headers, 2)
+			assert.Equal(t, res, provider.opts.Headers)
+		}
+	})
 }
 
 type fakeHttpClientProvider struct {