go-config is a library written in Golang designed to provide an easy interface with which to deal with configuration objects. Unlike many other similar libraries, go-config treats configuration objects as if they are members of a tree; that is to say that they can have parents and children. If a value is missing in a child configuration object, it will look to its parent for the answer recursively.

go-config makes certain assumptions about your directory layout. It assumes you have a single configuration directory (usually called "config") in which there are several JSON files corresponding to your configuration sets. An example directory layout is presented below:

config/
├── default.json
├── development.json
└── production.json

0 directories, 3 files

Each file is scoped to a single environment, and all files are JSON-encoded. Valid environment names are listed below:

• "production"
• "staging"
• "development"
• "default"

go-config picks up your environment by searching through OS-level environment variables. It searches through an exported variable it assumes to be called ENV. Values contained in this variable are allowed to be any case, so long as they are one of the four valid environments as provided above.

An example is provided below for fetching a value out of a configuration object:

package main

func main() {
        cfg, err := config.NewConfiguration(&config.Param{
                Directory: "./config",
                Environment: environment.Default, // optional
        })
        if err != nil {
                panic(err)
        }

        fmt.Println(cfg.String("mysql.user"))
}

From the above example, there are a few useful things to point out, namely the lookup syntax. For mapped values (map[string]interface{}), you are allowed to delimit those lookups by a .. For array lookups, you are allowed to delimit the indice of the array you are interested in by a ..

func main() {
        // ...

        cfg.String("db.mysql.username")
        cfg.String("dbs.1.username")
        cfg.String("db.mysql.users.0.username")
}

MIT.