Allow loading secrets from an additional configuration file.

Adds the `-secrets` command line flag, which defaults to `$CREDENTIALS_DIRECTORY/secrets.toml` if it exists. The secrets.toml file will be loaded the same way as the main config.toml.

Reviewed-on: https://codeberg.org/git-pages/git-pages/pulls/137
Reviewed-by: Catherine <whitequark@whitequark.org>
Co-authored-by: Andrew Cassidy <drewcassidy@me.com>
Co-committed-by: Andrew Cassidy <drewcassidy@me.com>

src/config.go

@@ -309,19 +309,17 @@ func PrintConfigEnvVars() {
 	})
 }
 
-func Configure(tomlPath string) (config *Config, err error) {
-	// start with an all-default configuration
-	config = new(Config)
-	defaults.MustSet(config)
-
-	// inject values from `config.toml`
+func ReadConfigFile(config *Config, tomlPath string) (err error) {
 	if tomlPath != "" {
 		var file *os.File
 		file, err = os.Open(tomlPath)
 		if err != nil {
 			return
 		}
-		defer file.Close()
+
+		defer func(file *os.File) {
+			err = file.Close()
+		}(file)
 
 		decoder := toml.NewDecoder(file)
 		decoder.DisallowUnknownFields()
@@ -330,6 +328,21 @@ func Configure(tomlPath string) (config *Config, err error) {
 			return
 		}
 	}
+	return nil
+}
+
+func Configure(tomlPaths ...string) (config *Config, err error) {
+	// start with an all-default configuration
+	config = new(Config)
+	defaults.MustSet(config)
+
+	// inject values from each toml file
+	for _, tomlPath := range tomlPaths {
+		err := ReadConfigFile(config, tomlPath)
+		if err != nil {
+			return nil, err
+		}
+	}
 
 	// inject values from the environment, overriding everything else
 	err = walkConfig(config, func(envName string, reflValue reflect.Value) error {

src/main.go

@@ -204,6 +204,8 @@ func Main(versionInfo string) {
 	flag.Usage = usage
 	configTomlPath := flag.String("config", "",
 		"load configuration from `filename` (default: 'config.toml')")
+	secretTomlPath := flag.String("secrets", "",
+		"load additional configuration values from `filename` (default: '$CREDENTIALS_DIRECTORY/secrets.toml' if it exists)")
 	noConfig := flag.Bool("no-config", false,
 		"run without configuration file (configure via environment variables)")
 	printConfigEnvVars := flag.Bool("print-config-env-vars", false,
@@ -291,7 +293,19 @@ func Main(versionInfo string) {
 	if *configTomlPath == "" && !*noConfig {
 		*configTomlPath = "config.toml"
 	}
-	if config, err = Configure(*configTomlPath); err != nil {
+
+	if *secretTomlPath == "" && !*noConfig {
+		// check for a second config file at $CREDENTIALS_DIRECTORY/secrets.toml, and use it
+		if systemdCredentialsDir := os.Getenv("CREDENTIALS_DIRECTORY"); systemdCredentialsDir != "" {
+			secretTomlTestPath := path.Join(systemdCredentialsDir, "secrets.toml")
+			_, err := os.Stat(secretTomlTestPath)
+			if !errors.Is(err, os.ErrNotExist) {
+				*secretTomlPath = secretTomlTestPath
+			}
+		}
+	}
+
+	if config, err = Configure(*configTomlPath, *secretTomlPath); err != nil {
 		logc.Fatalln(ctx, "config:", err)
 	}
 
@@ -602,7 +616,7 @@ func Main(versionInfo string) {
 		// Note that not all of the configuration is updated on reload. Listeners are kept as-is.
 		// The backend is not recreated (this is intentional as it allows preserving the cache).
 		OnReload(func() {
-			if newConfig, err := Configure(*configTomlPath); err != nil {
+			if newConfig, err := Configure(*configTomlPath, *secretTomlPath); err != nil {
 				logc.Println(ctx, "config: reload err:", err)
 			} else {
 				// From https://go.dev/ref/mem: