Add environment flag to config

config/config.go

@@ -16,12 +16,25 @@ const (
 	distConfigDir  = "./dist"
 )
 
+// Environment represents the environment in which the app is being run, such as development or production
+type Environment string
+
+const (
+	// EnvironmentDev represents the development environment
+	EnvironmentDev Environment = "dev"
+	// EnvironmentProd represents the production environment
+	EnvironmentProd = "prod"
+)
+
 // ErrDefaultConfig is thrown when the default configuration is used
 var ErrDefaultConfig = errors.New("config: using default configuration")
 
 // ErrConfigNotLoaded is returned when the config has not been loaded yet
 var ErrConfigNotLoaded = errors.New("config: config not loaded")
 
+// ErrBadEnvironment is returned when a bad environment is specified
+var ErrBadEnvironment = errors.New("config: invalid value for environment")
+
 // To prevent reading the config file each time we want a new config value, we store it as a package variable
 var config Config
 
@@ -30,6 +43,7 @@ type Config struct {
 	Server      ServerConfig
 	StoragePath string `yaml:"storage_path"`
 	DatabaseURI string `yaml:"database_uri"`
+	Environment Environment
 }
 
 // ServerConfig stores configuration for the webserver
@@ -38,6 +52,28 @@ type ServerConfig struct {
 	Port       int
 }
 
+// UnmarshalYAML performs standard unmarshaling, followed by validation of the Environment enum
+func (conf *Config) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	// Make a config type without the UnmarshalYAML function implemented, to avoid infinite recursion
+	type SafeConfig Config
+	safeConfig := (*SafeConfig)(conf)
+	err := unmarshal(safeConfig)
+	if err != nil {
+		return err
+	}
+
+	switch conf.Environment {
+	case "":
+		conf.Environment = EnvironmentProd
+		fallthrough
+	case EnvironmentDev, EnvironmentProd:
+		return nil
+	default:
+		conf.Environment = ""
+		return ErrBadEnvironment
+	}
+}
+
 // Get loads the currently stored config. If one is not stored, panic.
 func Get() Config {
 	if config == (Config{}) {