metrics-generator: don't inject X-Scope-OrgID header for single-tenan…

…t setups (#1417)

* metrics-generator: don't inject X-Scope-OrgID header for single-tenant setups

* Update CHANGELOG.md

CHANGELOG.md

@@ -1,5 +1,7 @@
 ## main / unreleased
 
+* [BUGFIX] metrics-generator: don't inject X-Scope-OrgID header for single-tenant setups [1417](https://github.com/grafana/tempo/pull/1417) (@kvrhdn)
+
 ## v1.4.0 / 2022-04-28
 
 * [CHANGE] Vulture now exercises search at any point during the block retention to test full backend search.

modules/generator/storage/config_util.go

@@ -7,6 +7,8 @@ import (
 	"github.com/go-kit/log/level"
 	prometheus_config "github.com/prometheus/prometheus/config"
 	"github.com/weaveworks/common/user"
+
+	"github.com/grafana/tempo/pkg/util"
 )
 
 // generateTenantRemoteWriteConfigs creates a copy of the remote write configurations with the
@@ -31,7 +33,9 @@ func generateTenantRemoteWriteConfigs(originalCfgs []prometheus_config.RemoteWri
 		}
 
 		// inject the X-Scope-OrgId header for multi-tenant metrics backends
-		cloneCfg.Headers[user.OrgIDHeaderName] = tenant
+		if tenant != util.FakeTenantID {
+			cloneCfg.Headers[user.OrgIDHeaderName] = tenant
+		}
 
 		cloneCfgs = append(cloneCfgs, cloneCfg)
 	}

modules/generator/storage/config_util_test.go

@@ -9,6 +9,8 @@ import (
 	prometheus_common_config "github.com/prometheus/common/config"
 	prometheus_config "github.com/prometheus/prometheus/config"
 	"github.com/stretchr/testify/assert"
+
+	"github.com/grafana/tempo/pkg/util"
 )
 
 func Test_generateTenantRemoteWriteConfigs(t *testing.T) {
@@ -39,6 +41,23 @@ func Test_generateTenantRemoteWriteConfigs(t *testing.T) {
 	assert.Equal(t, map[string]string{"foo": "bar", "X-Scope-OrgID": "my-tenant"}, result[1].Headers)
 }
 
+func Test_generateTenantRemoteWriteConfigs_singleTenant(t *testing.T) {
+	logger := log.NewLogfmtLogger(log.NewSyncWriter(os.Stdout))
+
+	original := []prometheus_config.RemoteWriteConfig{
+		{
+			URL:     &prometheus_common_config.URL{URL: urlMustParse("http://prometheus-1/api/prom/push")},
+			Headers: map[string]string{},
+		},
+	}
+
+	result := generateTenantRemoteWriteConfigs(original, util.FakeTenantID, logger)
+
+	assert.Equal(t, original[0].URL, result[0].URL)
+	// X-Scope-OrgID has not been injected
+	assert.Empty(t, result[0].Headers)
+}
+
 func Test_copyMap(t *testing.T) {
 	original := map[string]string{
 		"k1": "v1",