Add propagation of EnableOpenMetricsTextCreatedSamples to prometheus handler

.chloggen/openmetrics-created-timestamp.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: prometheusexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Add support for OpenMetrics created timestamp"
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: []
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

exporter/prometheusexporter/README.md

@@ -31,6 +31,7 @@ The following settings can be optionally configured:
 - `resource_to_telemetry_conversion`
   - `enabled` (default = false): If `enabled` is `true`, all the resource attributes will be converted to metric labels by default.
 - `enable_open_metrics`: (default = `false`): If true, metrics will be exported using the OpenMetrics format. Exemplars are only exported in the OpenMetrics format, and only for histogram and monotonic sum (i.e. counter) metrics.
+- `enable_open_metrics_text_created_samples`: (default = `false`): If true, and if `enable_open_metrics` is also true, the new metric `*_created` with the timestamp of the metric creation will additionally be added to counters, histograms, and summaries. See the [OpenMetrics created timestamp documentation](https://github.com/prometheus/OpenMetrics/blob/v1.0.0/specification/OpenMetrics.md#counter-1) for more details.
 - `add_metric_suffixes`: (default = `true`): If false, addition of type and unit suffixes is disabled. **Deprecated**: Use `translation_strategy` instead. This setting is ignored when `translation_strategy` is explicitly set.
 - `translation_strategy`: Controls how OTLP metric and attribute names are translated into Prometheus metric and label names. When set, this takes precedence over `add_metric_suffixes`. Available options:
   - `UnderscoreEscapingWithSuffixes`: Fully escapes metric names for classic Prometheus metric name compatibility, and includes appending type and unit suffixes.

exporter/prometheusexporter/config.go

@@ -41,6 +41,9 @@ type Config struct {
 	// EnableOpenMetrics enables the use of the OpenMetrics encoding option for the prometheus exporter.
 	EnableOpenMetrics bool `mapstructure:"enable_open_metrics"`
 
+	// EnableOpenMetricsTextCreatedSamples controls whether the created timestamp is added to metrics.
+	EnableOpenMetricsTextCreatedSamples bool `mapstructure:"enable_open_metrics_text_created_samples"`
+
 	// AddMetricSuffixes controls whether suffixes are added to metric names. Defaults to true.
 	// Deprecated: Use TranslationStrategy instead. This setting is ignored when TranslationStrategy is explicitly set.
 	AddMetricSuffixes bool `mapstructure:"add_metric_suffixes"`

exporter/prometheusexporter/factory.go

@@ -26,10 +26,11 @@
 
 func createDefaultConfig() component.Config {
 	return &Config{
 		ConstLabels:       map[string]string{},
 		SendTimestamps:    false,
 		MetricExpiration:  time.Minute * 5,
 		EnableOpenMetrics: false,
+		EnableOpenMetricsTextCreatedSamples: false,
 		AddMetricSuffixes: true,
 	}
 }

exporter/prometheusexporter/prometheus.go

@@ -54,9 +54,10 @@ func newPrometheusExporter(config *Config, set exporter.Settings) (*prometheusEx
 		handler: promhttp.HandlerFor(
 			registry,
 			promhttp.HandlerOpts{
-				ErrorHandling:     promhttp.ContinueOnError,
-				ErrorLog:          newPromLogger(set.Logger),
-				EnableOpenMetrics: config.EnableOpenMetrics,
+				ErrorHandling:                       promhttp.ContinueOnError,
+				ErrorLog:                            newPromLogger(set.Logger),
+				EnableOpenMetrics:                   config.EnableOpenMetrics,
+				EnableOpenMetricsTextCreatedSamples: config.EnableOpenMetricsTextCreatedSamples,
 			},
 		),
 		settings: set.TelemetrySettings,

exporter/prometheusexporter/prometheus_test.go

@@ -696,3 +696,42 @@ this_one_there_where_{arch="x86",instance="test-instance",job="test-service",os=
 		})
 	}
 }
+
+func TestPrometheusExporter_OpenMetricsCreatedSamples(t *testing.T) {
+	addr := testutil.GetAvailableLocalAddress(t)
+	cfg := &Config{
+		Namespace: "test",
+		ServerConfig: confighttp.ServerConfig{
+			Endpoint: addr,
+		},
+		EnableOpenMetrics:                   true,
+		EnableOpenMetricsTextCreatedSamples: true,
+		SendTimestamps:                      true,
+		MetricExpiration:                    120 * time.Minute,
+	}
+
+	factory := NewFactory()
+	set := exportertest.NewNopSettings(metadata.Type)
+	exp, err := factory.CreateMetrics(t.Context(), set, cfg)
+	require.NoError(t, err)
+
+	defer func() { require.NoError(t, exp.Shutdown(t.Context())) }()
+
+	require.NoError(t, exp.Start(t.Context(), componenttest.NewNopHost()))
+
+	md := metricBuilder(0, "", "test-service", "test-instance")
+	assert.NoError(t, exp.ConsumeMetrics(t.Context(), md))
+
+	req, err := http.NewRequest(http.MethodGet, "http://"+addr+"/metrics", http.NoBody)
+	require.NoError(t, err)
+	req.Header.Set("Accept", "application/openmetrics-text;version=1.0.0;escaping=allow-utf-8")
+	res, err := http.DefaultClient.Do(req)
+	require.NoError(t, err)
+	assert.Equal(t, http.StatusOK, res.StatusCode)
+
+	blob, _ := io.ReadAll(res.Body)
+	_ = res.Body.Close()
+	output := string(blob)
+
+	assert.Contains(t, output, "test_this_one_there_where_created")
+}