pvormste / yetenv

A small util package which helps to determine on which environment the application is running

yetenv

yetenv is small util package which helps to detect on which environment the application is running and can load a configuration from a file into a configuration struct.

Install

go get -u github.com/pvormste/yetenv

Usage

1. Environment detection
2. Config Loader

Environment detection

Environment detection reads from a specific environment variable (Default: ENVIRONMENT). See examples below.

The ENVIRONMENT values are not case-sensitives.

ENVIRONMENT value	Constant
production	yetenv.Production
staging	yetenv.Staging
test	yetenv.Test
any other value	yetenv.Develop

Using the defaults

Shell:

$ ENVIRONMENT="production" go run main.go  # yetenv.Production
$ ENVIRONMENT="staging" go run main.go     # yetenv.Staging
$ ENVIRONMENT="test" go run main.go        # yetenv.Test
$ ENVIRONMENT="local" go run main.go       # yetenv.Develop

Go Code:

environment := yetenv.GetEnvironment()

switch environment {
case yetenv.Production:
    // Do something in production environment
case yetenv.Staging:
    // Do something in staging environment
case yetenv.Test:
    // Do something in test environment
case yetenv.Develop:
    // Do something in develop environment
}

Changing the default variable name

Shell:

$ APP_ENV="production" go run main.go   # yetenv.Production
$ APP_ENV="staging" go run main.go      # yetenv.Staging
$ APP_ENV="test" go run main.go         # yetenv.Test
$ APP_ENV="local" go run main.go         # yetenv.Develop

Go Code:

yetenv.DefaultVariableName = "APP_ENV"
environment := yetenv.GetEnvironment()

switch environment {
case yetenv.Production:
    // Do something in production environment
case yetenv.Staging:
    // Do something in staging environment
case yetenv.Test:
    // Do something in test environment
case yetenv.Develop:
    // Do something in develop environment
}

Reading temporary from a custom variable name

Shell:

$ APP_ENV="production" go run main.go   # yetenv.Production
$ APP_ENV="staging" go run main.go      # yetenv.Staging
$ APP_ENV="test" go run main.go         # yetenv.Test
$ APP_ENV="local" go run main.go        # yetenv.Develop

Go Code:

environment := yetenv.GetEnvironmentFromVariable("APP_ENV")

switch environment {
case yetenv.Production:
    // Do something in production environment
case yetenv.Staging:
    // Do something in staging environment
case yetenv.Test:
    // Do something in staging environment
case yetenv.Develop:
    // Do something in develop environment
}

Config Loader

The config loader is able to load a configuration from one or more files into a configuration struct. To achieve this, it uses the cleanenv package under the hood - so please have a look into their documentation to get familar about the usage of configuration structs.

It also comes with a set of defaults, so it can be used with zero configuration out of the box. Nevertheless it is possible to customize the behavior of the ConfigLoader, so it doesn't get in your way.

Default Load Behavior

The default load behavior works like this depending on the environment:

• For Develop: Load from ./cfg.dev.env and overwrite it by ./.env and OS environment values.
• For Test: Load from ./cfg.test.env and overwrite it by ./.env and OS environment values.
• For Staging: Load from ./cfg.staging.env and overwrite it by ./.env and OS environment values.
• For Production: Load from ./cfg.prod.env and overwrite it by ./.env and OS environment values.

c := Config{}
err := yetenv.NewConfigLoader().
   UseDefaultLoadBehavior().
   LoadInto(&c)

Change load path

• For Develop: Load from ./config/cfg.dev.env and overwrite it by ./config/.env and OS environment values.
• For Test: Load from ./config/cfg.test.env and overwrite it by ./config/.env and OS environment values.
• For Staging: Load from ./config/cfg.staging.env and overwrite it by ./config/.env and OS environment values.
• For Production: Load from ./config/cfg.prod.env and overwrite it by ./config/.env and OS environment values.

c := Config{}
err := yetenv.NewConfigLoader().
   UseLoadPath("./config").
   UseDefaultLoadBehavior().
   LoadInto(&c)

Change file processor

• For Develop: Load from ./cfg.dev.yaml and overwrite it by ./cfg.yaml and OS environment values.
• For Test: Load from ./cfg.test.yaml and overwrite it by ./cfg.yaml and OS environment values.
• For Staging: Load from ./cfg.staging.yaml and overwrite it by ./cfg.yaml and OS environment values.
• For Production: Load from ./cfg.prod.yaml and overwrite it by ./cfg.yaml and OS environment values.

c := Config{}
err := yetenv.NewConfigLoader().
   UseFileProcessor(yetenv.YAML).
   UseDefaultLoadBehavior().
   LoadInto(&c)

Change file name for a specific environment

The default load behavior works like this depending on the environment:

• For Develop: Load from ./cfg.local.env and overwrite it by ./.env and OS environment values.
• For Test: Load from ./cfg.testing.env and overwrite it by ./.env and OS environment values.
• For Staging: Load from ./cfg.qa.env and overwrite it by ./.env and OS environment values.
• For Production: Load from ./cfg.production.env and overwrite it by ./.env and OS environment values.

c := Config{}
err := yetenv.NewConfigLoader().
   UseFileNameForEnvironment(yetenv.Develop, "cfg.local").
   UseFileNameForEnvironment(yetenv.Test, "cfg.testing").
   UseFileNameForEnvironment(yetenv.Staging, "cfg.qa").
   UseFileNameForEnvironment(yetenv.Production, "cfg.production").
   UseDefaultLoadBehavior().
   LoadInto(&c)

Inject environment

By default the ConfigLoader will use yetenv.GetEnvironment() to detect the current environment. If you customize the environment detection you can inject it this way:

customEnvironment := yetenv.Staging
c := Config{}
err := yetenv.NewConfigLoader().
   UseEnvironment(customEnvironment).
   UseDefaultLoadBehavior().
   LoadInto(&c)

Custom Load Behavior

The custom load behavior is highly customizable - but keep in mind that some settings only applies when using specific setting methods.

Setting	Applies When using
UseLoadPath()	LoadFromFileForEnvironment()
UseFileProcessor()	LoadFromFileForEnvironment()
UseFileNameForEnvironment()	LoadFromFileForEnvironment()
UseEnvironment()	LoadFromFileForEnvironment() or LoadFromConditionalFile()

Example for a custom load behavior

• For Develop and Staging and Test: Load from ./cfg.base.env and overwrite by OS environment values.
• For Production: Load from ./config/cfg.prod.yaml and overwrite by OS environment values.
• For All Environments: Load from ./other-config/cfg.toml and overwrite by OS environment values.

developAndStagingCondition := func(configLoader *ConfigLoader, currentEnvironment Environment) bool {
   return currentEnvironment == yetenv.Develop || currentEnvironment == yetenv.Staging || currentEnvironment == yetenv.Test
}

customEnvironment := yetenv.Staging
c := Config{}
err := yetenv.NewConfigLoader().
   UseLoadPath("./config").
   UseFileProcessor(yetenv.YAML).
   UseEnvironment(customEnvironment).
   UseCustomLoadBehavior().
   LoadFromConditionalFile("./cfg.base.env", developAndStagingCondition).
   LoadFromFileForEnvironment(yetenv.Production).
   LoadFromFile("./other-config/cfg.toml").
   LoadInto(&c)

As you can see: you can do very complicated things with it - I personally would recommend to keep it simple :-).