[open-telemetry#58] ld gc flags

cmd/builder/internal/builder/config.go

@@ -31,6 +31,7 @@ type Config struct {
 	SkipGetModules       bool   `mapstructure:"-"`
 	SkipStrictVersioning bool   `mapstructure:"-"`
 	LDFlags              string `mapstructure:"-"`
+	GCFlags              string `mapstructure:"-"`
 	Verbose              bool   `mapstructure:"-"`
 
 	Distribution Distribution `mapstructure:"dist"`
@@ -68,7 +69,7 @@ type Distribution struct {
 	OutputPath               string `mapstructure:"output_path"`
 	Version                  string `mapstructure:"version"`
 	BuildTags                string `mapstructure:"build_tags"`
-	DebugCompilation         bool   `mapstructure:"debug_compilation"`
+	DebugCompilation         bool   `mapstructure:"debug_compilation"` // TODO required for backwards-compatibility with builds older than x.xx.x
 }
 
 // Module represents a receiver, exporter, processor or extension for the distribution

cmd/builder/internal/builder/config_test.go

@@ -153,6 +153,8 @@ func TestNewDefaultConfig(t *testing.T) {
 	assert.NoError(t, cfg.SetGoPath())
 	require.NoError(t, cfg.Validate())
 	assert.False(t, cfg.Distribution.DebugCompilation)
+	assert.Empty(t, cfg.LDFlags)
+	assert.Empty(t, cfg.GCFlags)
 	assert.Empty(t, cfg.Distribution.BuildTags)
 }
 

cmd/builder/internal/builder/main.go

@@ -109,19 +109,32 @@ func Compile(cfg Config) error {
 		return nil
 	}
 
+
 	cfg.Logger.Info("Compiling")
+	cfg.Logger.Info("distrubtion", zap.Any("distro", cfg.Distribution))
 
-	var ldflags = "-s -w"
+	var ldflags = "-s -w" // we strip the symbols by default for smaller binaries
+	var gcflags = ""
 
 	args := []string{"build", "-trimpath", "-o", cfg.Distribution.Name}
 	if cfg.Distribution.DebugCompilation {
 		cfg.Logger.Info("Debug compilation is enabled, the debug symbols will be left on the resulting binary")
 		ldflags = cfg.LDFlags
-		args = append(args, "-gcflags=all=-N -l")
-	} else if len(cfg.LDFlags) > 0 {
-		ldflags += " " + cfg.LDFlags
+		gcflags = "all=-N -l"
+	} else {
+		if len(cfg.LDFlags) > 0 {
+			cfg.Logger.Info("Using custom ldflags", zap.String("ldflags", cfg.LDFlags))
+			ldflags = cfg.LDFlags
+		}
+		if len(cfg.GCFlags) > 0 {
+			cfg.Logger.Info("Using custom gcflags", zap.String("gcflags", cfg.GCFlags))
+			gcflags = cfg.GCFlags
+		}
 	}
 	args = append(args, "-ldflags="+ldflags)
+	args = append(args, "-gcflags="+gcflags)
+
+
 	if cfg.Distribution.BuildTags != "" {
 		args = append(args, "-tags", cfg.Distribution.BuildTags)
 	}
@@ -130,6 +143,7 @@ func Compile(cfg Config) error {
 	}
 	cfg.Logger.Info("Compiled", zap.String("binary", fmt.Sprintf("%s/%s", cfg.Distribution.OutputPath, cfg.Distribution.Name)))
 
+	cfg.Logger.Info("arg", zap.Any("arguments", args))
 	return nil
 }
 

cmd/builder/internal/builder/main_test.go

@@ -290,6 +290,18 @@ func TestGenerateAndCompile(t *testing.T) {
 				return cfg
 			},
 		},
+		{
+			name: "GCFlags Compilation",
+			cfgBuilder: func(t *testing.T) Config {
+				cfg := newTestConfig()
+				err := cfg.SetBackwardsCompatibility()
+				require.NoError(t, err)
+				cfg.Distribution.OutputPath = t.TempDir()
+				cfg.Replaces = append(cfg.Replaces, replaces...)
+				cfg.GCFlags = `all=-N -l`
+				return cfg
+			},
+		},
 		{
 			name: "Build Tags Compilation",
 			cfgBuilder: func(t *testing.T) Config {

cmd/builder/internal/command.go

@@ -25,6 +25,7 @@ const (
 	skipGetModulesFlag             = "skip-get-modules"
 	skipStrictVersioningFlag       = "skip-strict-versioning"
 	ldflagsFlag                    = "ldflags"
+	gcflagsFlag 				   = "gcflags"
 	distributionNameFlag           = "name"
 	distributionDescriptionFlag    = "description"
 	distributionVersionFlag        = "version"
@@ -87,6 +88,7 @@ configuration is provided, ocb will generate a default Collector.
 	cmd.Flags().BoolVar(&cfg.SkipStrictVersioning, skipStrictVersioningFlag, true, "Whether builder should skip strictly checking the calculated versions following dependency resolution")
 	cmd.Flags().BoolVar(&cfg.Verbose, verboseFlag, false, "Whether builder should print verbose output (default false)")
 	cmd.Flags().StringVar(&cfg.LDFlags, ldflagsFlag, "", `ldflags to include in the "go build" command`)
+	cmd.Flags().StringVar(&cfg.GCFlags, gcflagsFlag, "", `gcflags to include in the "go build" command`)
 	cmd.Flags().StringVar(&cfg.Distribution.Name, distributionNameFlag, "otelcol-custom", "The executable name for the OpenTelemetry Collector distribution")
 	if err := cmd.Flags().MarkDeprecated(distributionNameFlag, "use config distribution::name"); err != nil {
 		return nil, err