Split Collector from the cobra.Command.

CHANGELOG.md

@@ -6,10 +6,11 @@
 
 - Move ValidateConfig from configcheck to configtest (#3956)
 - Remove AttributeMessageType (#4020)
-- Remove `mem-ballast-size-mib`, already deprecated and no-op (#4005).
-- Remove `AttributeHTTPStatusText` const, replaced with `"http.status_text"` (#4015, contrib/#5182).
-- Remove squash on `configtls.TLSClientSetting` and move TLS client configs under `tls` (#4063).
-- Rename TLS server config `*configtls.TLSServerSetting` from `tls_settings` to `tls` (#4063).
+- Remove `mem-ballast-size-mib`, already deprecated and no-op (#4005)
+- Remove `AttributeHTTPStatusText` const (#4015)
+- Remove squash on `configtls.TLSClientSetting` and move TLS client configs under `tls` (#4063)
+- Rename TLS server config `*configtls.TLSServerSetting` from `tls_settings` to `tls` (#4063)
+- Split `service.Collector` from the `cobra.Command` (#4074)
 
 ## v0.35.0 Beta
 

cmd/otelcol/main.go

@@ -48,8 +48,8 @@ func runInteractive(settings service.CollectorSettings) error {
 		return fmt.Errorf("failed to construct the collector server: %w", err)
 	}
 
-	err = app.Run()
-	if err != nil {
+	cmd := service.NewCommand(app)
+	if err = cmd.Execute(); err != nil {
 		return fmt.Errorf("collector server run finished with error: %w", err)
 	}
 

service/collector.go

@@ -19,14 +19,12 @@ package service
 import (
 	"context"
 	"errors"
-	"flag"
 	"fmt"
 	"os"
 	"os/signal"
 	"runtime"
 	"syscall"
 
-	"github.com/spf13/cobra"
 	"go.opentelemetry.io/contrib/zpages"
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/metric"
@@ -36,12 +34,10 @@ import (
 
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/config/configcheck"
-	"go.opentelemetry.io/collector/config/configtelemetry"
 	"go.opentelemetry.io/collector/config/configunmarshaler"
 	"go.opentelemetry.io/collector/config/experimental/configsource"
 	"go.opentelemetry.io/collector/consumer/consumererror"
 	"go.opentelemetry.io/collector/extension/ballastextension"
-	"go.opentelemetry.io/collector/internal/collector/telemetry"
 	"go.opentelemetry.io/collector/service/internal"
 	"go.opentelemetry.io/collector/service/internal/telemetrylogs"
 	"go.opentelemetry.io/collector/service/parserprovider"
@@ -59,20 +55,19 @@ const (
 
 // (Internal note) Collector Lifecycle:
 // - New constructs a new Collector.
-// - Run starts the collector and calls (*Collector).execute.
-// - execute calls setupConfigurationComponents to handle configuration.
+// - Run starts the collector.
+// - Run calls setupConfigurationComponents to handle configuration.
 //   If configuration parser fails, collector's config can be reloaded.
 //   Collector can be shutdown if parser gets a shutdown error.
-// - execute runs runAndWaitForShutdownEvent and waits for a shutdown event.
+// - Run runs runAndWaitForShutdownEvent and waits for a shutdown event.
 //   SIGINT and SIGTERM, errors, and (*Collector).Shutdown can trigger the shutdown events.
 // - Upon shutdown, pipelines are notified, then pipelines and extensions are shut down.
-// - Users can call (*Collector).Shutdown anytime to shutdown the collector.
+// - Users can call (*Collector).Shutdown anytime to shut down the collector.
 
 // Collector represents a server providing the OpenTelemetry Collector service.
 type Collector struct {
-	set     CollectorSettings
-	rootCmd *cobra.Command
-	logger  *zap.Logger
+	set    CollectorSettings
+	logger *zap.Logger
 
 	tracerProvider      trace.TracerProvider
 	meterProvider       metric.MeterProvider
@@ -107,57 +102,17 @@ func New(set CollectorSettings) (*Collector, error) {
 		set.ConfigUnmarshaler = configunmarshaler.NewDefault()
 	}
 
-	col := &Collector{
+	return &Collector{
 		set:          set,
 		stateChannel: make(chan State, Closed+1),
-	}
-
-	rootCmd := &cobra.Command{
-		Use:     set.BuildInfo.Command,
-		Version: set.BuildInfo.Version,
-		RunE: func(cmd *cobra.Command, args []string) error {
-			return col.execute(cmd.Context())
-		},
-	}
-
-	// TODO: coalesce this code and expose this information to other components.
-	flagSet := new(flag.FlagSet)
-	addFlagsFns := []func(*flag.FlagSet){
-		configtelemetry.Flags,
-		parserprovider.Flags,
-		telemetry.Flags,
-		telemetrylogs.Flags,
-	}
-	for _, addFlags := range addFlagsFns {
-		addFlags(flagSet)
-	}
-	rootCmd.Flags().AddGoFlagSet(flagSet)
-	col.rootCmd = rootCmd
-
-	return col, nil
-}
-
-// Run starts the collector according to the command and configuration
-// given by the user, and waits for it to complete.
-// Consecutive calls to Run are not allowed, Run shouldn't be called
-// once a collector is shut down.
-func (col *Collector) Run() error {
-	// From this point on do not show usage in case of error.
-	col.rootCmd.SilenceUsage = true
-
-	return col.rootCmd.Execute()
+	}, nil
 }
 
 // GetStateChannel returns state channel of the collector server.
 func (col *Collector) GetStateChannel() chan State {
 	return col.stateChannel
 }
 
-// Command returns Collector's root command.
-func (col *Collector) Command() *cobra.Command {
-	return col.rootCmd
-}
-
 // GetLogger returns logger used by the Collector.
 // The logger is initialized after collector server start.
 func (col *Collector) GetLogger() *zap.Logger {
@@ -246,7 +201,9 @@ func (col *Collector) setupConfigurationComponents(ctx context.Context) error {
 	return nil
 }
 
-func (col *Collector) execute(ctx context.Context) error {
+// Run starts the collector according to the given configuration given, and waits for it to complete.
+// Consecutive calls to Run are not allowed, Run shouldn't be called once a collector is shut down.
+func (col *Collector) Run(ctx context.Context) error {
 	col.zPagesSpanProcessor = zpages.NewSpanProcessor()
 	col.tracerProvider = sdktrace.NewTracerProvider(
 		sdktrace.WithSampler(internal.AlwaysRecord()),

service/collector_test.go

@@ -58,11 +58,11 @@ func TestCollector_Start(t *testing.T) {
 		LoggingOptions: []zap.Option{zap.Hooks(hook)},
 	})
 	require.NoError(t, err)
-	assert.Equal(t, col.rootCmd, col.Command())
 
 	const testPrefix = "a_test"
 	metricsPort := testutil.GetAvailablePort(t)
-	col.rootCmd.SetArgs([]string{
+	cmd := NewCommand(col)
+	cmd.SetArgs([]string{
 		"--config=testdata/otelcol-config.yaml",
 		"--metrics-addr=localhost:" + strconv.FormatUint(uint64(metricsPort), 10),
 		"--metrics-prefix=" + testPrefix,
@@ -71,7 +71,7 @@ func TestCollector_Start(t *testing.T) {
 	colDone := make(chan struct{})
 	go func() {
 		defer close(colDone)
-		assert.NoError(t, col.Run())
+		assert.NoError(t, cmd.Execute())
 	}()
 
 	assert.Equal(t, Starting, <-col.GetStateChannel())
@@ -123,12 +123,13 @@ func TestCollector_ReportError(t *testing.T) {
 	col, err := New(CollectorSettings{BuildInfo: component.DefaultBuildInfo(), Factories: factories})
 	require.NoError(t, err)
 
-	col.rootCmd.SetArgs([]string{"--config=testdata/otelcol-config-minimal.yaml"})
+	cmd := NewCommand(col)
+	cmd.SetArgs([]string{"--config=testdata/otelcol-config-minimal.yaml"})
 
 	colDone := make(chan struct{})
 	go func() {
 		defer close(colDone)
-		assert.EqualError(t, col.Run(), "failed to shutdown collector telemetry: err1")
+		assert.EqualError(t, cmd.Execute(), "failed to shutdown collector telemetry: err1")
 	}()
 
 	assert.Equal(t, Starting, <-col.GetStateChannel())
@@ -154,7 +155,7 @@ func TestCollector_StartAsGoRoutine(t *testing.T) {
 	colDone := make(chan struct{})
 	go func() {
 		defer close(colDone)
-		colErr := col.Run()
+		colErr := col.Run(context.Background())
 		if colErr != nil {
 			err = colErr
 		}

service/collector_windows.go

@@ -87,9 +87,12 @@ func (s *WindowsService) start(elog *eventlog.Log, colErrorChannel chan error) e
 		return err
 	}
 
-	// col.Start blocks until receiving a SIGTERM signal, so needs to be started
+	// col.Run blocks until receiving a SIGTERM signal, so needs to be started
 	// asynchronously, but it will exit early if an error occurs on startup
-	go func() { colErrorChannel <- s.col.Run() }()
+	go func() {
+		cmd := NewCommand(s.col)
+		colErrorChannel <- cmd.Execute()
+	}()
 
 	// wait until the collector server is in the Running state
 	go func() {

service/command.go

@@ -0,0 +1,54 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package service
+
+import (
+	"flag"
+
+	"github.com/spf13/cobra"
+
+	"go.opentelemetry.io/collector/config/configtelemetry"
+	"go.opentelemetry.io/collector/internal/collector/telemetry"
+	"go.opentelemetry.io/collector/service/internal/telemetrylogs"
+	"go.opentelemetry.io/collector/service/parserprovider"
+)
+
+// NewCommand constructs a new cobra.Command using the given Collector.
+// TODO: Make this independent of the collector internals.
+func NewCommand(col *Collector) *cobra.Command {
+	rootCmd := &cobra.Command{
+		Use:          col.set.BuildInfo.Command,
+		Version:      col.set.BuildInfo.Version,
+		SilenceUsage: true,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return col.Run(cmd.Context())
+		},
+	}
+
+	// TODO: coalesce this code and expose this information to other components.
+	flagSet := new(flag.FlagSet)
+	addFlagsFns := []func(*flag.FlagSet){
+		configtelemetry.Flags,
+		parserprovider.Flags,
+		telemetry.Flags,
+		telemetrylogs.Flags,
+	}
+	for _, addFlags := range addFlagsFns {
+		addFlags(flagSet)
+	}
+
+	rootCmd.Flags().AddGoFlagSet(flagSet)
+	return rootCmd
+}