Environment reader

EnvReader is a simple library to ease environment variable parsing into a given structure. This library reads a given structure, parses the wanted environment value and defaults, and fills the structure with this values.

How to use

In order to use this library, you need to define a data structure in Go, for example, we can define a simple configuration:

type Config struct {
    ListenHost string
    ListenPort string
    Debug      bool
    Numbers    []int

Once is defined, you need to define environment variable tags. You also can define a fallback value if this environment variable does not exist. In this example, we will define a default value for ListenHost and ListenPort, but not for Debug. Slice types are splitted with comma (,) value.

type Config struct {
    ListenHost string `env:"LISTEN_HOST" default:""`
    ListenPort string `env:"LISTEN_PORT" default:"5000"`
    Debug      bool   `env:"ENABLE_DEBUG"`
    Numbers    []int  `env:"NUMBERS" default:"1,2,3,4"`

Now, we will initialize the library and read all environment values into the structure:

var configuration Config

reader := envreader.EnvReader{}
if err := reader.Read(&configuration); err != nil {

If we get no error, now we can take a look on our configuration variable to check all variables are loaded correctly:

fmt.Printf("%+v\n", configuration)

Expected output:

{ListenHost: ListenPort:5000 Debug:false Numbers:[1 2 3 4]}

Supported datatypes

Currently, the following basic datatypes are supported:

  • Boolean
  • Integers: Int, Int64, Int32, Int16, Int8
  • Floats: Float64, Float32
  • Slices: []string, []int, []float32, []float64


Check the examples/ directory to get some examples.

Documentation & testing

This library is documented using GoDoc, so you can access to this documentation here. Or you can check directly using this command:

$ godoc -http=:6060


EnvReader is released under GNU General Public License. For more details, take a look at the LICENSE


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