Avoid duplicate Cobra CLI error output in generated commands

.chloggen/cobra-cli-error-builder.yaml

@@ -0,0 +1,4 @@
+change_type: bug_fix
+component: cmd/builder
+note: Fix duplicate error output when CLI command execution fails in the builder tool.
+issues: [14436]

.chloggen/cobra-cli-error-mdatagen.yaml

@@ -0,0 +1,4 @@
+change_type: bug_fix
+component: cmd/mdatagen
+note: Fix duplicate error output when CLI command execution fails in the mdatagen tool.
+issues: [14436]

cmd/builder/internal/command.go

@@ -34,9 +34,8 @@ const (
 // Command is the main entrypoint for this application
 func Command() (*cobra.Command, error) {
 	cmd := &cobra.Command{
-		SilenceUsage:  true, // Don't print usage on Run error.
-		SilenceErrors: true, // Don't print errors; main does it.
-		Use:           "ocb",
+		SilenceUsage: true, // Don't print usage on Run error.
+		Use:          "ocb",
 		Long: fmt.Sprintf("OpenTelemetry Collector Builder (%s)", version) + `
 
 ocb generates a custom OpenTelemetry Collector binary using the

cmd/builder/internal/command_test.go

@@ -4,6 +4,7 @@
 package internal
 
 import (
+	"bytes"
 	"strings"
 	"testing"
 
@@ -24,11 +25,10 @@ func TestCommand(t *testing.T) {
 		{
 			name: "command created",
 			want: &cobra.Command{
-				SilenceUsage:  true, // Don't print usage on Run error.
-				SilenceErrors: true, // Don't print errors; main does it.
-				Use:           "ocb",
-				Long:          "OpenTelemetry Collector Builder",
-				Args:          cobra.NoArgs,
+				SilenceUsage: true, // Don't print usage on Run error.
+				Use:          "ocb",
+				Long:         "OpenTelemetry Collector Builder",
+				Args:         cobra.NoArgs,
 			},
 			wantErr: false,
 		},
@@ -55,6 +55,23 @@ func TestCommand(t *testing.T) {
 	}
 }
 
+func TestCommandErrorOutputOnce(t *testing.T) {
+	cmd, err := Command()
+	require.NoError(t, err)
+
+	var stderr bytes.Buffer
+	cmd.SetErr(&stderr)
+	cmd.SetArgs([]string{"/nonexistent/path/metadata.yaml"})
+
+	err = cmd.Execute()
+	require.Error(t, err)
+	out := stderr.String()
+	require.NotEmpty(t, out)
+
+	msg := err.Error()
+	assert.Equal(t, 1, strings.Count(out, msg), out)
+}
+
 func TestApplyFlags(t *testing.T) {
 	tests := []struct {
 		name  string

cmd/builder/main.go

@@ -4,6 +4,8 @@
 package main
 
 import (
+	"os"
+
 	"github.com/spf13/cobra"
 
 	"go.opentelemetry.io/collector/cmd/builder/internal"
@@ -12,5 +14,8 @@ import (
 func main() {
 	cmd, err := internal.Command()
 	cobra.CheckErr(err)
-	cobra.CheckErr(cmd.Execute())
+
+	if err := cmd.Execute(); err != nil {
+		os.Exit(1)
+	}
 }

cmd/mdatagen/internal/command_test.go

@@ -10,6 +10,7 @@ import (
 	"go/token"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"github.com/spf13/cobra"
@@ -39,6 +40,23 @@ func TestCommandNoArgs(t *testing.T) {
 	require.Error(t, err)
 }
 
+func TestCommandErrorOutputOnce(t *testing.T) {
+	cmd, err := NewCommand()
+	require.NoError(t, err)
+
+	var stderr bytes.Buffer
+	cmd.SetErr(&stderr)
+	cmd.SetArgs([]string{"/nonexistent/path/metadata.yaml"})
+
+	err = cmd.Execute()
+	require.Error(t, err)
+	out := stderr.String()
+	require.NotEmpty(t, out)
+
+	msg := err.Error()
+	assert.Equal(t, 1, strings.Count(out, msg), out)
+}
+
 func TestRunContents(t *testing.T) {
 	tests := []struct {
 		yml                  string

cmd/mdatagen/main.go

@@ -6,6 +6,8 @@ package main
 //go:generate mdatagen metadata.yaml
 
 import (
+	"os"
+
 	"github.com/spf13/cobra"
 
 	"go.opentelemetry.io/collector/cmd/mdatagen/internal"
@@ -14,5 +16,8 @@ import (
 func main() {
 	cmd, err := internal.NewCommand()
 	cobra.CheckErr(err)
-	cobra.CheckErr(cmd.Execute())
+
+	if err := cmd.Execute(); err != nil {
+		os.Exit(1)
+	}
 }