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Godotenv in Go

Brief introduction

Twelve-factor applications advocate storing configurations in environment variables. Anything that needs to be modified when switching from a development environment to a production environment is extracted from the code into environment variables. However, in actual development, if multiple projects are run on the same machine, setting environment variables is easy to conflict and impractical. The godotenv library reads the configuration from the .env file and stores it in the program's environment variables. It is very convenient to use reading in your code. Godotenv comes from dotenv, an open source project of Ruby.

Quick use

Third-party libraries need to be installed first:

$go get github.com/joho/godotenv

After use:

Package mainimport ("fmt"log"os"github.com/joho/godotenv") func main () {err: = godotenv.Load () if err! = nil {log.Fatal (err)} fmt.Println ("name:", os.Getenv ("name")) fmt.Println ("age:", os.Getenv ("age"))}

Then add a .env file in the same directory as the executable:

Name = dj

Age = 18

Run the program, output:

Name: dj

Age: 18

It can be seen that it is very convenient to use. By default, godotenv reads the .env file in the root directory of the project, using the format key = value, with one key-value pair per line. It can be loaded by calling godotenv.Load (), and can be read directly by calling os.Getenv ("key"). Os.Getenv is used to read environment variables:

Package mainimport ("fmt"os") func main () {fmt.Println (os.Getenv ("GOPATH"))}

Advanced featur

Automatic loading

If you have the tradition of being lazy as a programmer, you may not even want to call the Load method yourself. It doesn't matter, godotenv gives you the right to be lazy!

Import github.com/joho/godotenv/autoload, and the configuration automatically reads:

Package mainimport ("fmt"os" _ "github.com/joho/godotenv/autoload") func main () {fmt.Println ("name:", os.Getenv ("name")) fmt.Println ("age:", os.Getenv ("age"))}

Note that since the godotenv library is not explicitly used in the code, you need to use an empty import, that is, adding a _ before the package name when importing.

Look at the source code of the autoload package. In fact, the library calls the Load method for you:

/ / src/github.com/joho/godotenv/autoload/autoload.gopackage autoload

/ * You can just read the .env file on import just by doingimport _ "github.com/joho/godotenv/autoload" And bob's your mother's brother*/import "github.com/joho/godotenv" func init () {godotenv.Load ()}

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