Worker: log which config paths are used at startup

To aid in debugging configuration loading issues, log the paths to config
files at startup.

CHANGELOG.md

@@ -19,6 +19,7 @@ bugs in actually-released versions.
   - [GO-2024-3106: Stack exhaustion in Decoder.Decode in encoding/gob](https://pkg.go.dev/vuln/GO-2024-3106)
 - Fix bug where database foreign key constraints could be deactivated ([#104305](https://projects.blender.org/studio/flamenco/issues/104305)).
 - Fix bug when submitting a file with a non-ASCII name via Shaman ([#104338](https://projects.blender.org/studio/flamenco/issues/104338)).
+- Worker: log the configuration file locations at startup.
 
 ## 3.5 - released 2024-04-16
 

cmd/flamenco-worker/main.go

@@ -95,6 +95,11 @@ func main() {
 
 	// Load configuration, and override things from the CLI arguments if necessary.
 	configWrangler := worker.NewConfigWrangler()
+	configPaths := configWrangler.ConfigPaths()
+	log.Info().
+		Str("main", configPaths.Main).
+		Str("credentials", configPaths.Credentials).
+		Msg("will load configuration from these paths")
 
 	// Before the config can be overridden, it has to be loaded.
 	if _, err := configWrangler.WorkerConfig(); err != nil {

internal/worker/config.go

@@ -89,6 +89,41 @@ func NewConfigWrangler() FileConfigWrangler {
 	return FileConfigWrangler{}
 }
 
+type WorkerConfigPaths struct {
+	Main        string
+	Credentials string
+}
+
+// ConfigPaths returns the absolute file paths Flamenco Worker will use to load
+// its configuration. If the path cannot be made absolute, an error will be
+// logged and a relative path will be returned instead.
+func (fcw *FileConfigWrangler) ConfigPaths() WorkerConfigPaths {
+	var err error
+	paths := WorkerConfigPaths{}
+
+	// configFilename is used as-is.
+	paths.Main, err = filepath.Abs(configFilename)
+	if err != nil {
+		log.Error().
+			AnErr("cause", err).
+			Str("filepath", configFilename).
+			Msg("could not make the main configuration file path an absolute path")
+		paths.Main = configFilename
+	}
+
+	// credentialsFilename is always looked up somewhere in the user's home dir.
+	paths.Credentials, err = fcw.credentialsAbsPath()
+	if err != nil {
+		log.Error().
+			AnErr("cause", err).
+			Str("filepath", credentialsFilename).
+			Msg("could not make the credentials configuration file path an absolute path")
+		paths.Credentials = credentialsFilename
+	}
+
+	return paths
+}
+
 // WorkerConfig returns the worker configuration, or the default config if
 // there is no config file. Configuration is only loaded from disk once;
 // subsequent calls return the same config.
@@ -150,7 +185,7 @@ func (fcw *FileConfigWrangler) WorkerCredentials() (WorkerCredentials, error) {
 func (fcw *FileConfigWrangler) SaveCredentials(creds WorkerCredentials) error {
 	fcw.creds = &creds
 
-	filepath, err := appinfo.InFlamencoHome(credentialsFilename)
+	filepath, err := fcw.credentialsAbsPath()
 	if err != nil {
 		return err
 	}
@@ -162,6 +197,11 @@ func (fcw *FileConfigWrangler) SaveCredentials(creds WorkerCredentials) error {
 	return nil
 }
 
+func (fcw *FileConfigWrangler) credentialsAbsPath() (string, error) {
+	filepath, err := appinfo.InFlamencoHome(credentialsFilename)
+	return filepath, err
+}
+
 // SetManagerURL overwrites the Manager URL in the cached configuration.
 // This is an in-memory change only, and will not be written to the config file.
 func (fcw *FileConfigWrangler) SetManagerURL(managerURL string) {