feat: prepend changelog flag

Author: christophwitzko

cmd/semantic-release/main.go

@@ -209,7 +209,17 @@ func cliHandler(cmd *cobra.Command, args []string) {
 		NewVersion:    newVer,
 	})
 	if conf.Changelog != "" {
-		exitIfError(ioutil.WriteFile(conf.Changelog, []byte(changelogRes), 0644))
+		oldFile := make([]byte, 0)
+		if conf.PrependChangelog {
+			oldFile, err = ioutil.ReadFile(conf.Changelog)
+			if err == nil {
+				oldFile = append([]byte("\n\n"), oldFile...)
+			} else {
+				oldFile = make([]byte, 0)
+			}
+		}
+		changelogData := append([]byte(changelogRes), oldFile...)
+		exitIfError(ioutil.WriteFile(conf.Changelog, changelogData, 0644))
 	}
 
 	if conf.Dry {

pkg/config/config.go

@@ -34,6 +34,7 @@ type Config struct {
 	AllowInitialDevelopmentVersions bool
 	AllowNoChanges                  bool
 	MaintainedVersion               string
+	PrependChangelog                bool
 }
 
 func mustGetString(cmd *cobra.Command, name string) string {
@@ -120,6 +121,7 @@ func NewConfig(cmd *cobra.Command) (*Config, error) {
 		AllowInitialDevelopmentVersions: mustGetBool(cmd, "allow-initial-development-versions"),
 		AllowNoChanges:                  mustGetBool(cmd, "allow-no-changes"),
 		MaintainedVersion:               viper.GetString("maintainedVersion"),
+		PrependChangelog:                mustGetBool(cmd, "prepend-changelog"),
 	}
 	return conf, nil
 }
@@ -171,6 +173,7 @@ func InitConfig(cmd *cobra.Command) error {
 	cmd.Flags().Bool("dry", false, "do not create release")
 	cmd.Flags().Bool("allow-initial-development-versions", false, "semantic-release will start your initial development release at 0.1.0")
 	cmd.Flags().Bool("allow-no-changes", false, "exit with code 0 if no changes are found, useful if semantic-release is automatically run")
+	cmd.Flags().Bool("prepend-changelog", false, "if the changelog file already exist the new changelog is prepended")
 	cmd.Flags().SortFlags = true
 
 	viper.AddConfigPath(".")