Programming language: Go
Tags: Configuration    
Latest version: v1.5.0

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This project has been completely revised and simplyfied in https://github.com/oblq/swap, consider using this one instead. This repository is archived and no longer mantained.


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Dynamically create toolbox singletons with automatic configuration based on your build environment.
SpareBox is also an agnostic, layered, config parser (supporting YAML, TOML, JSON and Environment vars).
Keep your projects and their configuration files ordered and maintainable.


Using dep:

dep ensure -add github.com/oblq/sprbox@master

...or go get:

go get -u github.com/oblq/sprbox

ToolBox autoload (init and config)

1. Define your toolbox.

Fields can be of any type, sprbox will init pointers and pass config files where needed (configurable structs, struct pointers, slices or maps).
To load a configuration file a field must implement the configurable interface.

type ToolBox struct {
    // By default sprbox will look for a file named like the
    // struct field name (Services.*, case sensitive).
    // Services.<environment>.yml will override Services.yml
    // for the given env, if exist.
    Services services.ServicesMap

    // MediaProcessing does not implement the 'configurable' interface
    // so it will be traversed recursively.
    // Recursion only stop when no more embedded elements are found 
    // or when a 'configurable' element is found instead.
    // 'configurable' elements will not be traversed.
    MediaProcessing struct {
        // Optionally pass one or more specific config file name, 
        // separated by the pipe symbol: |.
        // The latest will overrides others, from right to left,
        // you can see that using sprbox.SetDebug(true).
        // sprbox will always try to find the file named
        // like the struct field first (Pictures.*).
        // File extension can be omitted.
        // Use a sub-directory for embedded structs to keep things ordered:
        // mp/Pics -> "./config/mp/Pics.*"
        Pictures services.Service `sprbox:"mp/Pics|mp/PicsOverride"`
        Videos   services.Service

    WP  Workerful
    // Workerful implement the 'configurableInCollections' interface,
    // so it can be loaded also directly inside 
    // slices or maps using a single config file.
    WPS []Workerful 

    // will print the error in console
    ToolMissingConfig *Tool

    // Optionally add the 'omit' value to skip a field.
    OmittedTool Tool `sprbox:"omit"`

var ToolBox MyToolBox
2. Init and configure the toolbox in one line.

In sprbox.LoadToolBox() environment-specific config files (cfg.<environment>.*) will override generic ones (cfg.*):

// Optionally set debug mode.
// sprbox.SetDebug(true)
sprbox.LoadToolBox(&ToolBox, "./config")

NOTE: tool's exported pointer fields will be automatically initialized before to call the configurable interface.


The build environment

The build environment is determined matching a tag against some predefined environment specific RegEx, since any of the env's RegEx can be edited users have the maximum flexibility on the method to use.
For instance, the machine hostname (cat /etc/hostname) can be used.

sprbox will try to grab that tag in three different ways, in a precise order, if one can't be determined it will check for the next one:

  1. The BUILDENV var in sprbox package:

    sprbox.BUILDENV = "dev"

    Since it is an exported string, can also be interpolated with -ldflags at build/run time:

    LDFLAGS="-X ${GOPATH:-$HOME/go}/src/github.com/oblq/sprbox.BUILDENV=develop"
    go build -ldflags "${LDFLAGS}" -v -o ./api_bin ./api
  2. The environment variable 'BUILD_ENV':

    // sprbox.EnvVarKey is 'BUILD_ENV'
    os.Setenv(sprbox.EnvVarKey, "dev")
  3. The Git branch name (Gitflow supported).
    By default the working dir is used, you can pass a different git repository path for this:

    sprbox.VCS = sprbox.NewRepository("path/to/repo")
    println(sprbox.VCS.BranchName) // Commit, Tag, Build, Path and Error
  4. When you run tests the environment will be set automatically to 'testing' if not set manually and no git repo is found in the project root.

Every environment has a set of default RegEx:

Production  = []string{"production", "master"}
Staging     = []string{"staging", "release/*", "hotfix/*"}
Testing     = []string{"testing", "test"}
Development = []string{"development", "develop", "dev", "feature/*"}
Local       = []string{"local"}

...and they can be edited:

sprbox.Testing.SetExps([]string{"testing", "test"})
println("matched:", sprbox.Testing.MatchTag("feature/f5"))

Finally you can check the current env in code with:

if sprbox.Env() == sprbox.Production { 

Working with directories

Sparebox offer two utility funcs to work with directories.

  1. EnvSubDir()
    ...pretty much self-explanatory: go sprbox.EnvSubDir("static") // -> "static/<environment>" (eg.: "static/staging")
  2. CompiledPath()
    If the current build-environment has RunCompiled == true sprbox.CompiledPath() returns the path base, so static files can stay side by side with the executable while it is possible to have a different location when the program is launched with go run.
    This allow to manage multiple packages in one project during development, for instance using a config path in the parent dir, side by side with the packages, while having the same config folder side by side with the executable where needed.

    sprbox.BUILDENV = sprbox.Development.ID()   
    sprbox.Development.RunCompiled = false   
    sprbox.CompiledPath("../static_files/config") // -> "../static_files/config"
    sprbox.Development.RunCompiled = true   
    sprbox.CompiledPath("../static_files/config") // -> "config"

    A simple usage example is:

    sprbox.LoadToolBox(&myToolBox, sprbox.CompiledPath("../config"))

    By default only Production and Staging environments have RunCompiled true.

    Using your package in sprbox

To start using your package in sprbox you just need to implement the configurable interface:

type configurable interface {
    SpareConfig([]string) error

// optional, allow to load the package from a slice or a map directly.
type configurableInCollection interface {
    SpareConfigBytes([]byte) error


type MyPackage struct {
    Something string `yaml:"something"`

// SpareConfig is the sprbox 'configurable' interface implementation.
// (mp *MyPackage) is automatically initialized with a pointer to MyPackage{}
// so it will never be nil, but needs configuration.
func (mp *MyPackage) SpareConfig(configFiles []string) (err error) {
    var config *MyPackageConfig
    err = sprbox.LoadConfig(&cfg, configFiles...)       

// SpareConfigBytes optionally allow to load MyPackage inside a slice or a map directly.
func (mp *MyPackage) SpareConfigBytes(configBytes []byte) (err error) {
    var config *MyPackageConfig
    err = sprbox.Unmarshal(configBytes, &cfg)

Add sprbox in your repo topics and/or the 'sprbox-ready' badge if you like it: sprbox

Embed third-party packages in sprbox

Suppose we want to embed packagex.StructX:

type StructX struct {

func (sx *StructX) SpareConfig(configFiles []string) (err error) {
    var cfg packagex.Config
    err = sprbox.LoadConfig(&cfg, configFiles...)       
    sx.StructX = packagex.NewStructX(cfg)

From here on you can use the StructX in a toolbox with automatic init/config:

type ToolBox struct {
    SX StructX

var App ToolBox

func init() {
    // ./config must contain SX.(yml|yaml|json|toml) config file in that case.
    sprbox.LoadToolBox(&App, "./config") 

    // Call any of the packagex.StructX's funcs on SX.
    // Initialized and configured.

Agnostic, layered, config unmarshaling

Given that project structure:

├── config
│   ├── pg.yaml
│   └── pg.production.yaml
└── main.go


port: 2222


port: 2345

...to unmarshal that config files to a struct you just need to call sprbox.LoadConfig(&pgConfig, "config/pg.yaml"):

package main

import (


type PostgresConfig struct{
    // Environment vars overrides both default values and config file provided values.
    DB       string `sprbox:"env=POSTGRES_DB,default=postgres"`
    User     string `sprbox:"env=POSTGRES_USER,default=postgres"`
    // If no value is found that will return an error: 'required'.
    Password string `sprbox:"env=POSTGRES_PASSWORD,required"`
    Port     int    `sprbox:"default=5432"`

func main() {
    os.Setenv("POSTGRES_PASSWORD", "123_only_known_by_me")

    // Setting 'production' build-environment,
    // so 'pg.production.yml' will override 'pg.yml'.
    sprbox.BUILDENV = sprbox.Production.ID() // -> 'production'

    var pgConfig PostgresConfig 
    if err := sprbox.LoadConfig(&pgConfig, "config/pg.yaml"); err != nil {

    fmt.Printf("%#v\n", pgConfig) 
    // Config{
    //      DB:         "postgres"
    //      User:       "postgres"
    //      Password:   "123_only_known_by_me"
    //      Port:       2345
    // }

Depending on the build environment, trying to load config/pg.yml will also load config/pg.<environment>.yml (eg.: cfg.production.yml).
If any environment-specific file will be found, for the current environment, that will override the generic one.

It is possible to load multiple separated config files, also of different type, so components configs can be reused. Be aware that:

  1. YAML files uses lowercased keys by default, unless you define a custom field tag (struct field Postgres will become "postgres", while in TOML or JSON it will remain "Postgres").
  2. The default map interface is map[interface{}]interface{} in YAML, not map[string]interface{} as in JSON or TOML.
func main() {
    // File extension can be omitted:
    var pusherConfig PushNotificationsConfig    
    sprbox.LoadConfig(&pusherConfig, "config/pusher.yml", "config/postgres.json")

The file extension in the file path can be omitted, since sprbox can load YAML, TOML and JSON files it will search for cfg.* using RegEx, the config file itself must have an extension.

Also, LoadConfig() will parse text/template placeholders in config files, the key used in placeholders must match the key of the config interface, case-sensitive:

type Config struct {
    Base string
    URL string
base: "https://example.com"
url: "{{.Base}}/api/v1" # -> will be parsed to: "https://example.com/api/v1"


  • [example](example)

To start it run:

make example

Ready packages

  • [common](common)
    • [Services](common/services) Service/micro-service/monolith abstraction, get services URL, Proxy, Version, Basepath, hold custom Data etc...
  • Workerful Full-featured worker-pool implementation.

Vendored packages



SpareBox is available under the MIT license. See the [LICENSE](./LICENSE) file for more information.

*Note that all licence references and agreements mentioned in the sprbox README section above are relevant to that project's source code only.