code review changes

.chloggen/metric-server-hostproc.yaml

@@ -1,5 +1,5 @@
 # One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
-change_type: bug_fix
+change_type: breaking
 
 # The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
 component: service/proctelemetry
@@ -13,4 +13,6 @@ issues: [7434]
 # (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: This is an API change only, allowing users to set a value to override the environment variable HOST_PROC.
+subtext: |
+  This is an API change only, allowing users to set a value to override the environment variable HOST_PROC.
+  This change affects the proctelemetry.RegisterProcessMetrics function, adding a vararg argument to pass options.

service/internal/proctelemetry/process_telemetry.go

@@ -51,9 +51,34 @@ type processMetrics struct {
 	ms         *runtime.MemStats
 }
 
+type RegisterOption interface {
+	apply(*registerOption)
+}
+
+type registerOption struct {
+	hostProc string
+}
+
+type registerOptionFunc func(*registerOption)
+
+func (fn registerOptionFunc) apply(set *registerOption) {
+	fn(set)
+}
+
+// WithHostProc overrides the /proc folder on Linux used by process telemetry.
+func WithHostProc(hostProc string) RegisterOption {
+	return registerOptionFunc(func(uo *registerOption) {
+		uo.hostProc = hostProc
+	})
+}
+
 // RegisterProcessMetrics creates a new set of processMetrics (mem, cpu) that can be used to measure
 // basic information about this process.
-func RegisterProcessMetrics(ocRegistry *metric.Registry, mp otelmetric.MeterProvider, useOtel bool, ballastSizeBytes uint64, hostProc string) error {
+func RegisterProcessMetrics(ocRegistry *metric.Registry, mp otelmetric.MeterProvider, useOtel bool, ballastSizeBytes uint64, opts ...RegisterOption) error {
+	set := registerOption{}
+	for _, opt := range opts {
+		opt.apply(&set)
+	}
 	var err error
 	pm := &processMetrics{
 		startTimeUnixNano: time.Now().UnixNano(),
@@ -62,8 +87,8 @@ func RegisterProcessMetrics(ocRegistry *metric.Registry, mp otelmetric.MeterProv
 	}
 
 	ctx := context.Background()
-	if hostProc != "" {
-		ctx = context.WithValue(ctx, common.EnvKey, common.EnvMap{common.HostProcEnvKey: hostProc})
+	if set.hostProc != "" {
+		ctx = context.WithValue(ctx, common.EnvKey, common.EnvMap{common.HostProcEnvKey: set.hostProc})
 	}
 	pm.context = ctx
 	pm.proc, err = process.NewProcessWithContext(pm.context, int32(os.Getpid()))

service/internal/proctelemetry/process_telemetry_test.go

@@ -105,7 +105,7 @@ func fetchPrometheusMetrics(handler http.Handler) (map[string]*io_prometheus_cli
 func TestOtelProcessTelemetry(t *testing.T) {
 	tel := setupTelemetry(t)
 
-	require.NoError(t, RegisterProcessMetrics(nil, tel.MeterProvider, true, 0, ""))
+	require.NoError(t, RegisterProcessMetrics(nil, tel.MeterProvider, true, 0))
 
 	mp, err := fetchPrometheusMetrics(tel.promHandler)
 	require.NoError(t, err)
@@ -137,7 +137,7 @@ func TestOtelProcessTelemetry(t *testing.T) {
 func TestOCProcessTelemetry(t *testing.T) {
 	ocRegistry := metric.NewRegistry()
 
-	require.NoError(t, RegisterProcessMetrics(ocRegistry, noop.NewMeterProvider(), false, 0, ""))
+	require.NoError(t, RegisterProcessMetrics(ocRegistry, noop.NewMeterProvider(), false, 0))
 
 	// Check that the metrics are actually filled.
 	time.Sleep(200 * time.Millisecond)
@@ -174,7 +174,7 @@ func TestProcessTelemetryFailToRegister(t *testing.T) {
 			ocRegistry := metric.NewRegistry()
 			_, err := ocRegistry.AddFloat64Gauge(metricName)
 			require.NoError(t, err)
-			assert.Error(t, RegisterProcessMetrics(ocRegistry, noop.NewMeterProvider(), false, 0, ""))
+			assert.Error(t, RegisterProcessMetrics(ocRegistry, noop.NewMeterProvider(), false, 0))
 		})
 	}
 }

service/service.go

@@ -207,7 +207,7 @@ func (srv *Service) initExtensionsAndPipeline(ctx context.Context, set Settings,
 
 	if cfg.Telemetry.Metrics.Level != configtelemetry.LevelNone && cfg.Telemetry.Metrics.Address != "" {
 		// The process telemetry initialization requires the ballast size, which is available after the extensions are initialized.
-		if err = proctelemetry.RegisterProcessMetrics(srv.telemetryInitializer.ocRegistry, srv.telemetryInitializer.mp, obsreportconfig.UseOtelForInternalMetricsfeatureGate.IsEnabled(), getBallastSize(srv.host), ""); err != nil {
+		if err = proctelemetry.RegisterProcessMetrics(srv.telemetryInitializer.ocRegistry, srv.telemetryInitializer.mp, obsreportconfig.UseOtelForInternalMetricsfeatureGate.IsEnabled(), getBallastSize(srv.host)); err != nil {
 			return fmt.Errorf("failed to register process metrics: %w", err)
 		}
 	}