[exporter/prometheusremotewrite] Add the possibility to disable queui…

…ng (#6718)

* [prometheusremotewriteexporter] Add the possibility to disable queuing

A new configuration key, `remote_write queue.enabled` is added, which
controls the queue enabling.

* [exporter/awsprometheusremotewriteexporter] Fix config unit tests.

Update the expected prometheusremotewriteexporter default config.

exporter/awsprometheusremotewriteexporter/config_test.go

@@ -64,6 +64,7 @@ func TestLoadConfig(t *testing.T) {
 				MaxElapsedTime:  10 * time.Minute,
 			},
 			RemoteWriteQueue: prw.RemoteWriteQueue{
+				Enabled:      true,
 				QueueSize:    10000,
 				NumConsumers: 5,
 			},

exporter/prometheusremotewriteexporter/README.md

@@ -39,7 +39,8 @@ The following settings can be optionally configured:
   - *Note the following headers cannot be changed: `Content-Encoding`, `Content-Type`, `X-Prometheus-Remote-Write-Version`, and `User-Agent`.*
 - `namespace`: prefix attached to each exported metric name.
 - `remote_write_queue`: fine tuning for queueing and sending of the outgoing remote writes.
-  - `queue_size`: number of OTLP metrics that can be queued.
+  - `enabled`: enable the sending queue
+  - `queue_size`: number of OTLP metrics that can be queued. Ignored if `enabled` is `false`
   - `num_consumers`: minimum number of workers to use to fan out the outgoing requests.
 
 Example:

exporter/prometheusremotewriteexporter/config.go

@@ -51,8 +51,12 @@ type Config struct {
 
 // RemoteWriteQueue allows to configure the remote write queue.
 type RemoteWriteQueue struct {
+	// Enabled if false the queue is not enabled, the export requests
+	// are executed synchronously.
+	Enabled bool `mapstructure:"enabled"`
+
 	// QueueSize is the maximum number of OTLP metric batches allowed
-	// in the queue at a given time.
+	// in the queue at a given time. Ignored if Enabled is false.
 	QueueSize int `mapstructure:"queue_size"`
 
 	// NumWorkers configures the number of workers used by
@@ -69,6 +73,11 @@ func (cfg *Config) Validate() error {
 	if cfg.RemoteWriteQueue.QueueSize < 0 {
 		return fmt.Errorf("remote write queue size can't be negative")
 	}
+
+	if cfg.RemoteWriteQueue.Enabled && cfg.RemoteWriteQueue.QueueSize == 0 {
+		return fmt.Errorf("a 0 size queue will drop all the data")
+	}
+
 	if cfg.RemoteWriteQueue.NumConsumers < 0 {
 		return fmt.Errorf("remote write consumer number can't be negative")
 	}

exporter/prometheusremotewriteexporter/config_test.go

@@ -60,6 +60,7 @@ func Test_loadConfig(t *testing.T) {
 				MaxElapsedTime:  10 * time.Minute,
 			},
 			RemoteWriteQueue: RemoteWriteQueue{
+				Enabled:      true,
 				QueueSize:    2000,
 				NumConsumers: 10,
 			},
@@ -103,3 +104,14 @@ func TestNegativeNumConsumers(t *testing.T) {
 	_, err = configtest.LoadConfigAndValidate(path.Join(".", "testdata", "negative_num_consumers.yaml"), factories)
 	assert.Error(t, err)
 }
+
+func TestDisabledQueue(t *testing.T) {
+	factories, err := componenttest.NopFactories()
+	assert.NoError(t, err)
+
+	factory := NewFactory()
+	factories.Exporters[typeStr] = factory
+	cfg, err := configtest.LoadConfigAndValidate(path.Join(".", "testdata", "disabled_queue.yaml"), factories)
+	assert.NoError(t, err)
+	assert.False(t, cfg.Exporters[config.NewComponentID(typeStr)].(*Config).RemoteWriteQueue.Enabled)
+}

exporter/prometheusremotewriteexporter/factory.go

@@ -65,7 +65,7 @@ func createMetricsExporter(_ context.Context, set component.ExporterCreateSettin
 		prwe.PushMetrics,
 		exporterhelper.WithTimeout(prwCfg.TimeoutSettings),
 		exporterhelper.WithQueue(exporterhelper.QueueSettings{
-			Enabled:      true,
+			Enabled:      prwCfg.RemoteWriteQueue.Enabled,
 			NumConsumers: 1,
 			QueueSize:    prwCfg.RemoteWriteQueue.QueueSize,
 		}),
@@ -101,6 +101,7 @@ func createDefaultConfig() config.Exporter {
 		},
 		// TODO(jbd): Adjust the default queue size.
 		RemoteWriteQueue: RemoteWriteQueue{
+			Enabled:      true,
 			QueueSize:    10000,
 			NumConsumers: 5,
 		},

exporter/prometheusremotewriteexporter/testdata/disabled_queue.yaml

@@ -0,0 +1,21 @@
+receivers:
+    nop:
+
+processors:
+    nop:
+
+exporters:
+    prometheusremotewrite:
+        endpoint: "localhost:8888"
+        remote_write_queue:
+            enabled: false
+            num_consumers: 10
+
+service:
+    pipelines:
+        metrics:
+            receivers: [nop]
+            processors: [nop]
+            exporters: [prometheusremotewrite]
+
+