Just another config package

This is here because viper didn't work for me on windows.

Get Started

Example:

type Config struct {
    Host string `yaml:"host" default:"localhost"`
    Port int    `default:"8080"`
    Database struct {
        Name string `default:"postgres"`
        Port int    `default:"5432"`
    } `yaml:"database"`

    Other string `config:"weird-name"`
}

func main() {
    c := &Config{}
    config.SetConfig(c)
    config.SetType("yaml")
    config.AddFile("config.yml") // look for a file named "config.yaml"
    config.AddPath(".")          // look for the config file in "."
    err := config.ReadConfigFile()
    if err == config.NoConfigFile {
        // handle
    }

    // Defaults are set
    fmt.Println(config.GetInt("port")) // 8080
    fmt.Println(config.GetString("database.name")) // postgres
    fmt.Println(config.GetString("database.port")) // 5432

    // Alternate naming
    fmt.Println(config.Get("Other") == config.Get("weird-name")) // true

    // Values are also set on the struct
    fmt.Println(config.GetInt("port") == c.Port) // true
}

Struct tags

For better of for worse, this library relies on struct tags for customization.

tag	description
config	change config name and give other info
default	give the field a default value
env	check this environment variable to get a value

Default Values

When initializing a configuration struct, the package will look for the struct tag called default and set the default value from the tag value. This feature only supports a limited number of types such as string types and integer types.

By default, this feature will only work when using the global "getter" functions like config.Get or config.GetInt and will not work for the actual struct that is passed to config.SetConfig. To set the default values to the raw config struct, you need to call config.InitDefaults.

Flag Binding

If you want to change config values using command line options, you can bind the current config struct to a flag set.

Struct tags for flag binding

tag	description	example
usage	usage for the flag	`config:"name,usage=this is the name flag"`
shorthand	give the flag a shorthand (only for pflag)	`config:"name,shorthand=n"`
notflag	mark the config field as not a flag	`config:"file,notflag"`

// test.go
import "flag"

type Config struct {
    Name string `config:"name,shorthand=n,usage=give the name"`
    Inner struct {
        Val int `config:"val,usage=nested flag"`
    } `config:"inner"`
}
config.SetConfig(&Config{})
config.BindToFlagSet(
    flag.CommandLine,
    config.NewFlagInfo("name", "n", "give the name"),
    config.NewFlagInfo("inner-val", "", "nested flag"),
)
flag.Parse()

Keep in mind that function call order matters here. Calling config.BindToFlagSet before config.SetConfig means that there is no current config struct and will most likely result in a nil pointer panic.

$ go run ./test.go -help

Usage of /tmp/go-build123456789/b001/exe/test:
  -name value
        give the name
  -inner-val value
        nested flag

This feature also supports the common flag package drop in replacement called github.com/spf13/pflag and can be accessed using BindToPFlagSet(set *pflag.FlagSet). The shorthand option is only used with this package.

harrybrwn / config