env

env is a Go package for safely extracting and parsing environment variables using a pre-defined schema with support for generic types.

Getting Started

The env package can be added to a project by running:

go get cattlecloud.net/go/env@latest

import "cattlecloud.net/go/env"

Examples

basics

Use env.ParseOS and env.Schema for conveniently extracting values from the operating system environment variables.

var (
  home       string
  gomaxprocs int
)

err := env.ParseOS(env.Schema{
  "HOME":       env.String(&home, true),
  "GOMAXPROCS": env.Int(&gomaxprocs, true),
})

fallbacks

the StringOr and IntOr variants can be used to provide fallback values in case the environment variables are not set.

err := env.ParseOS(env.Schema{
  "HOME":       env.StringOr(&home, "/doesnotexist"),
  "GOMAXPROCS": env.IntOr(&gomaxprocs, 8),
})

generics

The Schema parsing is compatible with generic types, so if you have custom types like UUID backed by string or ID backed by integers, they can still be used as targets for extraction.

type (
  uuid      string
  timestamp int64
)

var (
  id       uuid
  creation timestamp
)

err := env.ParseOS(env.Schema{
  "ID":       env.String(&id, true),
  "CREATED":  env.Int(&creation, true),
})

environments

In addition to ParseOS, other parsers include

• ParseFile - for parsing a file containing environment variable key-value pairs
• ParseMap - for parsing a Go map containing string key-value pairs
• Parse[Environment] for parsing arbitrary implementations of the Environment type

License

The cattlecloud.net/go/env module is open source under the BSD license.