refactor(builder): change output of version subcommand.

If version information has not been inserted by `ldflags`,
the build information embedded in the binary being executed is output.

Return an error when failing to retrieve the version, and to use cobra's `RunE`.

cmd/builder/internal/version.go

@@ -5,22 +5,42 @@ package internal // import "go.opentelemetry.io/collector/cmd/builder/internal"
 
 import (
 	"fmt"
+	"runtime/debug"
 
 	"github.com/spf13/cobra"
 )
 
 var (
-	version = "dev"
+	version = ""
 	date    = "unknown"
 )
 
+// binVersion returns the version of the binary.
+// If the version is not set, it attempts to read the build information.
+// Returns an error if the build information cannot be read.
+func binVersion() (string, error) {
+	if version != "" {
+		return version, nil
+	}
+	info, ok := debug.ReadBuildInfo()
+	if !ok {
+		return "", fmt.Errorf("failed to read build info")
+	}
+	return info.Main.Version, nil
+}
+
 func versionCommand() *cobra.Command {
 	return &cobra.Command{
 		Use:   "version",
 		Short: "Version of ocb",
 		Long:  "Prints the version of the ocb binary",
-		Run: func(cmd *cobra.Command, args []string) {
+		RunE: func(cmd *cobra.Command, args []string) error {
+			version, err := binVersion()
+			if err != nil {
+				return err
+			}
 			cmd.Println(fmt.Sprintf("%s version %s", cmd.Parent().Name(), version))
+			return nil
 		},
 	}
 }