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2.0 KiB

Simple config reading for Go using reflection


Sample config file:

# A comment
filesize = 10MB
log_level = Debug
log_file = /var/log/my.log

Quotes are not trimmed. Whitespaces before and after the value are trimmed.

Unmarshal config into struct

type Settings struct {
    ServerPort int        `cfg:"server_port" default:"8080"`	// config value; if not found in config default is used
    Filesize cfg.Filesize `cfg:"filesize"`			// returns bytes of specified filesize 

type Log struct {
    File    string   `cfg:"log_file"`	// config value without default; if not found an error is returned
    Level   LogLevel `cfg:"log_level"`	// custom LogLevel type unmarshals the value "info" or "debug" into type LogLevel

type LogLevel int				// custom int type which holds the log level

const (
    Info = iota				// iota value for log levels

func (lm *LogLevel) Unmarshal(value string) error {		// the custom unmarshaler for the log level
    if strings.ToLower(value) == "info" {
            *lm = LogLevel(Info)
            return nil
    } else if strings.ToLower(value) == "debug" {
            *lm = LogLevel(Debug)
            return nil

    return fmt.Errorf("unexpected config value '%s' for log level", value)

func main() {
    c := cfg.ConfigFiles{}				// create a new config which holds the an array of files
    c.AddConfig("/etc", myconfig.conf)		// convenient method for adding a file
    settings := new(Settings)		
    def, err := c.MergeConfigsInto(settings)	// merges the config values into the setting struct

    if err != nil {

    for k, v := range def {				// applied defaults
        fmt.Printf("using default value %s for key %s\n", v.Value, k)