Addressing PR review feedback

internal/runtime/foreach_test.go

@@ -39,6 +39,26 @@ func TestForeach(t *testing.T) {
 	}
 }
 
+func TestForeachMetrics(t *testing.T) {
+	directory := "./testdata/foreach_metrics"
+	for _, file := range getTestFiles(directory, t) {
+		tc := buildTestForEach(t, filepath.Join(directory, file.Name()))
+		t.Run(tc.description, func(t *testing.T) {
+			if tc.module != "" {
+				defer os.Remove("module.alloy")
+				require.NoError(t, os.WriteFile("module.alloy", []byte(tc.module), 0664))
+			}
+			if tc.update != nil {
+				testConfigForEach(t, tc.main, tc.reloadConfig, func() {
+					require.NoError(t, os.WriteFile(tc.update.name, []byte(tc.update.updateConfig), 0664))
+				}, tc.expectedMetrics, tc.expectedDurationMetrics)
+			} else {
+				testConfigForEach(t, tc.main, tc.reloadConfig, nil, tc.expectedMetrics, tc.expectedDurationMetrics)
+			}
+		})
+	}
+}
+
 type testForEachFile struct {
 	description             string      // description at the top of the txtar file
 	main                    string      // root config that the controller should load
@@ -115,11 +135,9 @@ func testConfigForEach(t *testing.T, config string, reloadConfig string, update
 			"alloy_component_evaluation_seconds",
 		}
 
-		if countedMetrics, err := testutil.GatherAndCount(reg, metricsToCheck...); err != nil {
-			require.NoError(t, err)
-		} else {
-			require.Equal(t, *expectedDurationMetrics, countedMetrics)
-		}
+		countedMetrics, err := testutil.GatherAndCount(reg, metricsToCheck...)
+		require.NoError(t, err)
+		require.Equal(t, *expectedDurationMetrics, countedMetrics)
 	}
 
 	if expectedMetrics != nil {
@@ -132,9 +150,8 @@ func testConfigForEach(t *testing.T, config string, reloadConfig string, update
 			"pulse_count",
 		}
 
-		if err := testutil.GatherAndCompare(reg, strings.NewReader(*expectedMetrics), metricsToCheck...); err != nil {
-			require.NoError(t, err)
-		}
+		err := testutil.GatherAndCompare(reg, strings.NewReader(*expectedMetrics), metricsToCheck...)
+		require.NoError(t, err)
 	}
 
 	if update != nil {

internal/runtime/internal/controller/node_config_foreach.go

@@ -118,9 +118,13 @@ func (fn *ForeachConfigNode) ID() ComponentID {
 // Foreach doesn't have the ability to export values.
 // This is something we could implement in the future if there is a need for it.
 type Arguments struct {
-	Collection    []any  `alloy:"collection,attr"`
-	Var           string `alloy:"var,attr"`
-	EnableMetrics bool   `alloy:"enable_metrics,attr,optional"`
+	Collection []any  `alloy:"collection,attr"`
+	Var        string `alloy:"var,attr"`
+
+	// enable_metrics should be false by default.
+	// That way users are protected from an explosion of debug metrics
+	// if there are many items inside "collection".
+	EnableMetrics bool `alloy:"enable_metrics,attr,optional"`
 }
 
 func (fn *ForeachConfigNode) Evaluate(evalScope *vm.Scope) error {

internal/runtime/internal/testcomponents/pulse.go

@@ -76,6 +76,7 @@ func (p *Pulse) Run(ctx context.Context) error {
 				for _, r := range p.cfg.ForwardTo {
 					r.ReceiveInt(1)
 				}
+				p.pulseCount.Inc()
 				p.count++
 			}
 			p.cfgMut.Unlock()

internal/runtime/testdata/foreach_metrics/foreach_1.txtar

@@ -1,4 +1,5 @@
-Foreach with only one item. The pulse will send "1" to the receiver of the summation component until it reaches 10.
+Test to make sure debug metrics are disabled by default for foreach.
+Use a foreach with only one item. The pulse will send "1" to the receiver of the summation component until it reaches 10.
 
 -- main.alloy --
 foreach "testForeach" {

internal/runtime/testdata/foreach_metrics/foreach_2.txtar

@@ -1,3 +1,4 @@
+Test to make sure debug metrics for foreach are shown when they are enabled explicitly. 
 Foreach with only one item. The pulse will send "1" to the receiver of the summation component until it reaches 10.
 
 -- main.alloy --
@@ -35,7 +36,7 @@ alloy_component_evaluation_queue_size{controller_id="",controller_path="/"} 1
 alloy_component_evaluation_queue_size{controller_id="foreach_10_1",controller_path="/foreach.testForeach"} 0
 # HELP pulse_count
 # TYPE pulse_count counter
-pulse_count{component_id="testcomponents.pulse.pt",component_path="/foreach.testForeach/foreach_10_1"} 0
+pulse_count{component_id="testcomponents.pulse.pt",component_path="/foreach.testForeach/foreach_10_1"} 10
 
 -- expected_duration_metrics.prom --
 

internal/runtime/testdata/foreach_metrics/foreach_3.txtar

@@ -0,0 +1,46 @@
+This test uses two different items in the collection.
+
+-- main.alloy --
+foreach "testForeach" {
+  collection = [6,4]
+  var = "num"
+  enable_metrics = true
+
+  template {
+    testcomponents.pulse "pt" {
+      max = num
+      frequency = "10ms"
+      forward_to = [testcomponents.summation_receiver.sum.receiver]
+    }
+  }
+}
+
+// Similar to testcomponents.summation, but with a "receiver" export
+testcomponents.summation_receiver "sum" {
+}
+
+-- expected_metrics.prom --
+
+# HELP alloy_component_controller_evaluating Tracks if the controller is currently in the middle of a graph evaluation
+# TYPE alloy_component_controller_evaluating gauge
+alloy_component_controller_evaluating{controller_id="",controller_path="/"} 0
+alloy_component_controller_evaluating{controller_id="foreach_4_1",controller_path="/foreach.testForeach"} 0
+alloy_component_controller_evaluating{controller_id="foreach_6_1",controller_path="/foreach.testForeach"} 0
+# HELP alloy_component_controller_running_components Total number of running components.
+# TYPE alloy_component_controller_running_components gauge
+alloy_component_controller_running_components{controller_id="",controller_path="/",health_type="healthy"} 2
+alloy_component_controller_running_components{controller_id="foreach_4_1",controller_path="/foreach.testForeach",health_type="healthy"} 1
+alloy_component_controller_running_components{controller_id="foreach_6_1",controller_path="/foreach.testForeach",health_type="healthy"} 1
+# HELP alloy_component_evaluation_queue_size Tracks the number of components waiting to be evaluated in the worker pool
+# TYPE alloy_component_evaluation_queue_size gauge
+alloy_component_evaluation_queue_size{controller_id="",controller_path="/"} 1
+alloy_component_evaluation_queue_size{controller_id="foreach_4_1",controller_path="/foreach.testForeach"} 0
+alloy_component_evaluation_queue_size{controller_id="foreach_6_1",controller_path="/foreach.testForeach"} 0
+# HELP pulse_count
+# TYPE pulse_count counter
+pulse_count{component_id="testcomponents.pulse.pt",component_path="/foreach.testForeach/foreach_4_1"} 4
+pulse_count{component_id="testcomponents.pulse.pt",component_path="/foreach.testForeach/foreach_6_1"} 6
+
+-- expected_duration_metrics.prom --
+
+6