Add extra_labels object to BlackboxTarget block (#5157)

---------

Co-authored-by: Clayton Cornell <[email protected]>

CHANGELOG.md

@@ -44,6 +44,8 @@ Main (unreleased)
 - Add a `file_watch` block in `loki.source.file` to configure how often to poll files from disk for changes via `min_poll_frequency` and `max_poll_frequency`.
   In static mode it can be configured in the global `file_watch_config` via `min_poll_frequency` and `max_poll_frequency`.  (@wildum)
 
+- Flow: In `prometheus.exporter.blackbox`, allow setting labels for individual targets. (@spartan0x117)
+
 ### Enhancements
 
 - Clustering: allow advertise interfaces to be configurable, with the possibility to select all available interfaces. (@wildum)

component/prometheus/exporter/blackbox/blackbox.go

@@ -38,6 +38,10 @@ func buildBlackboxTargets(baseTarget discovery.Target, args component.Arguments)
 	a := args.(Arguments)
 	for _, tgt := range a.Targets {
 		target := make(discovery.Target)
+		// Set extra labels first, meaning that any other labels will override
+		for k, v := range tgt.Labels {
+			target[k] = v
+		}
 		for k, v := range baseTarget {
 			target[k] = v
 		}
@@ -62,9 +66,10 @@ var DefaultArguments = Arguments{
 
 // BlackboxTarget defines a target to be used by the exporter.
 type BlackboxTarget struct {
-	Name   string `river:",label"`
-	Target string `river:"address,attr"`
-	Module string `river:"module,attr,optional"`
+	Name   string            `river:",label"`
+	Target string            `river:"address,attr"`
+	Module string            `river:"module,attr,optional"`
+	Labels map[string]string `river:"labels,attr,optional"`
 }
 
 type TargetBlock []BlackboxTarget

component/prometheus/exporter/blackbox/blackbox_test.go

@@ -170,3 +170,47 @@ func TestBuildBlackboxTargets(t *testing.T) {
 	require.Equal(t, "http://example.com", targets[0]["__param_target"])
 	require.Equal(t, "http_2xx", targets[0]["__param_module"])
 }
+
+func TestBuildBlackboxTargetsWithExtraLabels(t *testing.T) {
+	baseArgs := Arguments{
+		ConfigFile: "modules.yml",
+		Targets: TargetBlock{{
+			Name:   "target_a",
+			Target: "http://example.com",
+			Module: "http_2xx",
+			Labels: map[string]string{
+				"env": "test",
+				"foo": "bar",
+			},
+		}},
+		ProbeTimeoutOffset: 1.0,
+	}
+	baseTarget := discovery.Target{
+		model.SchemeLabel:                   "http",
+		model.MetricsPathLabel:              "component/prometheus.exporter.blackbox.default/metrics",
+		"instance":                          "prometheus.exporter.blackbox.default",
+		"job":                               "integrations/blackbox",
+		"__meta_agent_integration_name":     "blackbox",
+		"__meta_agent_integration_instance": "prometheus.exporter.blackbox.default",
+	}
+	args := component.Arguments(baseArgs)
+	targets := buildBlackboxTargets(baseTarget, args)
+	require.Equal(t, 1, len(targets))
+	require.Equal(t, "integrations/blackbox/target_a", targets[0]["job"])
+	require.Equal(t, "http://example.com", targets[0]["__param_target"])
+	require.Equal(t, "http_2xx", targets[0]["__param_module"])
+
+	require.Equal(t, "test", targets[0]["env"])
+	require.Equal(t, "bar", targets[0]["foo"])
+
+	// Check that the extra labels do not override existing labels
+	baseArgs.Targets[0].Labels = map[string]string{
+		"job":      "test",
+		"instance": "test-instance",
+	}
+	args = component.Arguments(baseArgs)
+	targets = buildBlackboxTargets(baseTarget, args)
+	require.Equal(t, 1, len(targets))
+	require.Equal(t, "integrations/blackbox/target_a", targets[0]["job"])
+	require.Equal(t, "prometheus.exporter.blackbox.default", targets[0]["instance"])
+}

docs/sources/flow/reference/components/prometheus.exporter.blackbox.md

@@ -87,7 +87,7 @@ debug metrics.
 ### Collect metrics using a blackbox exporter config file
 
 This example uses a [`prometheus.scrape` component][scrape] to collect metrics
-from `prometheus.exporter.blackbox`:
+from `prometheus.exporter.blackbox`. It adds an extra label, `env="dev"`, to the metrics emitted by the `grafana` target. The `example` target does not have any added labels.
 
 ```river
 prometheus.exporter.blackbox "example" {
@@ -101,6 +101,9 @@ prometheus.exporter.blackbox "example" {
   target "grafana" {
     address = "http://grafana.com"
     module  = "http_2xx"
+    labels = {
+      "env": "dev",
+    }
   }
 }
 
@@ -144,6 +147,9 @@ prometheus.exporter.blackbox "example" {
   target "grafana" {
     address = "http://grafana.com"
     module  = "http_2xx"
+    labels = {
+      "env": "dev",
+    }
   }
 }
 
@@ -171,4 +177,5 @@ Replace the following:
 - `USERNAME`: The username to use for authentication to the remote_write API.
 - `PASSWORD`: The password to use for authentication to the remote_write API.
 
+
 [scrape]: {{< relref "./prometheus.scrape.md" >}}