goenvgen

Automatically generate Go Code from dotenv files.

This cli automatically determines the type information from the dotenv information and generates a Go package that can retrieve it. os.GetEnv the code becomes complicated because of the lack of type information. This package eliminates the need to use os.GetEnv.

Usage

Installation

# Go >= 1.17:
$ go install github.com/potproject/goenvgen

# Go < 1.17:
$ go get github.com/potproject/goenvgen

Generate Code

Add your application configuration to your .env file in the root of your project.

BASE_HOST=localhost
BASE_PORT=8080
ADMIN_IDS=123,234,345,456

USER_JSON={"Alice": {"ID": 100}, "Bob": {"ID": 200}}

The following code will be generated automatically Go Package.

$ goenvgen -p envgen .env
Generated envgen Packages.

$ tree envgen
envgen
├── USER_JSON.go
└── envgen.go

About generated package

This package itself does not read environment variables from dotenv, so joho/godotenv is required if you want to use .env file.

This is because it may control whether the dotenv file is loaded in the production and development environments.

Example Codes:

package main

import (
	"fmt"
	"log"

	"github.com/joho/godotenv"
	"[Your package path]/envgen"
)

func main() {
	// Loading .env file
	err := godotenv.Load()
	if err != nil {
		log.Fatal("Error loading .env file")
	}

	// Setup envgen package from environment variables
	err = envgen.Load()
	if err != nil {
		log.Fatal(err)
	}

	// Getting Environment Variables
	host := envgen.Get().BASE_HOST()
	port := envgen.Get().BASE_PORT()
	fmt.Printf("Running to http://%s:%d/", host, port)
  
	// Slice Type
	ids := envgen.Get().ADMIN_IDS()
	for _, id := range ids {
		fmt.Printf("ID: %d \r\n", id)
	}

	// JSON Type
	user := envgen.Get().USER_JSON()
	fmt.Printf("Bod ID: %d \r\n", user.Bob.ID)
}

Results:

$ go run main.go
Running to http://localhost:8080/
ID: 123 
ID: 234
ID: 345
ID: 456
Bob ID: 200

Enjoy Development!

Details

Usage of envgen:
  -p string
        the name of the package for the generated code (default "envgen")
  -r string
        Required Type setting (example: "-r ENV_REQ_BOOL,ENV_REQ_STRING")
  -t string
        Manually type definition setting (example: "-t ENV_BOOL=bool,ENV_S_INT=[]int")

Automatic determination of type

At the time of code generation, the type is automatically assigned from the values in the .env file.

Automatic generation is generated by the following rule.

value	is Type ...	Example
JSON strings	Generate struct for ChimeraCoder/gojson	'{"Alice": {"ID": 100}, "Bob": {"ID": 200}}'
`true` or `false`	`boolean`	'true'
integral number	`int64`	'123'
floating point number	`float64`	'1.1'
`true` or `false` with comma	`[]boolean`	'true,false'
integral number with comma	`[]int64`	'100,200'
floating point number with comma	`[]float64`	'0.1,0.2'
charactor with comma	`[]string`	'string1,string2'
otherwise	`string`	'string'

Manual determination of type

The type can be set manually by specifying the -t option when generating the code.

The types that can be set are bool, int, int8, int16, int32, int64, uint8, uint16, uint32, uint64, float32, float64, interface, and string. or their slice types.

Example:

goenvgen -p envgen -t BASE_PORT=uint16,ADMIN_IDS=[]int

Required Environment Variable

You can make the value required by specifying the -r option when generating the code.

Example:

BASE_HOST=
BASE_PORT=8080

goenvgen -p envgen -r BASE_HOST,BASE_PORT

$ go run .\main.go
BASE_HOST is required

Development & Contributing

Contributions are most welcome!

$ git clone https://https://github.com/potproject/goenvgen.git

# Code Generating Test
$ cd test
$ vi .env.test # Change .env.test File
$ go run main.go
$ go test ./envgentest/

License

MIT License