Support multiple API keys (command-line and config) (fixes #2747)

lib/config/guiconfiguration.go

@@ -76,9 +76,17 @@ func (c GUIConfiguration) URL() string {
 	return u.String()
 }
 
-func (c GUIConfiguration) APIKey() string {
-	if override := os.Getenv("STGUIAPIKEY"); override != "" {
-		return override
+// Returns whether the given API key is valid, including both the value in config
+// and any overrides
+func (c GUIConfiguration) IsValidAPIKey(apiKey string) bool {
+	switch apiKey {
+	case "":
+		return false
+
+	case c.RawAPIKey, os.Getenv("STGUIAPIKEY"):
+		return true
+
+	default:
+		return false
 	}
-	return c.RawAPIKey
 }