envtags

It is more about studying Go reflection approach than to create something better than what already exists, but an useful package with a complete documentation may come out of this.

envtags is a package to use struct tags to automatically load environment variables on them.

Requirements

Go >= 1.18

Usage

Define a struct with the env tag on exported fields to bind the fields with environment variables

On an environment with the corresponding variables set, bind the struct to these variables using the method envtags.Set()

export BAR="13" 

package main

import "github.com/taciogt/envtags"

type Config struct {
  Foo int `env:"BAR"`
}

func main() {
  var config Config
  if err := envtags.Set(&config); err != nil {
    log.Fatal(err)
  }
}

If the environment variable value can not be parsed to the field type, an envtags.ErrInvalidTypeConversion error is returned.

If the field type is not supported, an envtags.ErrParserNotAvailable is returned.

Supported types

• Primitives
  • bool
  • string
  • int, int64, int32, int16, int8
  • uint, uint64, uint32, uint16, uint8
  • float32, float64
  • complex64, complex128
  • byte
• Non primitives
  • structs

Refs

Better test output with:

go install github.com/rakyll/gotest

Inspired by

• https://github.com/kelseyhightower/envconfig/blob/master/envconfig.go
• https://github.com/caarlos0/env

References

• Go numeric types
• godoc
• docs tips
• docs examples