nxconfig

NX Config (Go)

NX Config can be used to map environment variables and flags to struct values. Using reflection (exported) struct field names. Nested structs will be prefixed with the field name.

Usage

import (
    "log"
    "time"

    "github.com/expo21xx/nxconfig"
)

type Config struct {
    Host string
    Port uint16
    PGConfig PGConfig `name:"PG"`
}

type PGConfig struct {
    Host string `default:"localhost"`
    Port uint16 `default:"5432"`
    Username string `usage:"postgres username"`
    Password string
    Timeout time.Duration `name:"connection-timeout"`
}

func main() {
    var cfg Config

    err := nxconfig.Load(&cfg)
    if err != nil {
        log.Fatal(err)
    }

    // use cfg
}

Starting the binary will now parse all flags, and check all environment variables.

NOTE: Flags override environment variables!

Options

The Load function can be customized with a number of helper functions, passed in after the target.

nxconfig.Load(&target, nxconfig.WithArgs([]string{"--override", "foo"}), nxconfig.WithEnv([]string{}))

If you already use spf13/pflag you can pass the *pflag.FlagSet to Load:

nxconfig.Load(&target, nxconfig.WithFlagSet(myflagset))

NOTE: Load will call flagset.Parse() with the arguments it was passed, either with WithArgs or os.Args[1:] if not.

Struct Tags:

• name: name in PascalCase (overrides automatic inferring). NOTE: Use an empty "" to not export the field.
• default: default value
• usage: usage string to print when --help flag is passed

Supported Types

The currently supported types are:

• string
• int, int32, int64
• uint, uint32, uint64
• flaot32, flaot64
• bool
• time.Duration

More types will be added in future on a need to implement basis.