maxwww / dotenv

Yet another dotenv Go port.

dotenv

Yet another Go port of dotenv environment variable dot-file library.

Installation

go get github.com/stackus/dotenv

Usage

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

S3_BUCKET=YOURS3BUCKET
SECRET_KEY=YOURSECRETKEYGOESHERE

Load()

Use Load() to inject the variables read from the files into the current processes environment variables.

Load the variables in Go like the following:

package main

import (
	"fmt"
	"os"
	
	"github.com/stackus/dotenv"
)

func main() {
    if err := dotenv.Load(); err != nil {
        fmt.Fprintf(os.Stderr, "error starting application: %s", err)
        os.Exit(1)
    }
	
    s3Bucket := os.Getenv("S3_BUCKET")
    secretKey := os.Getenv("SECRET_KEY")
	
    // ...
}

Parse()

If you do not want to alter the environment variables you can use Parse() to return all of the values read from the file as a map[string]string.

// ...

values, err := dotenv.Parse()

s3Bucket := values["S3_BUCKET"]

// ...

Defaults

Setting	Default	Purpose
Files	.env	Names of the files that should be parsed for values
Paths	.	Paths that should be searched for files
Overload	false	Replace existing environment variables with values read in from files
RequireAllFiles	false	Silently skip any files that could not be found and read
RequiredKeys	[]	List of keys that must exist in the environment

Options

Both Load() and Parse() accept options that will alter how they work.

Files(...string)

Provide a list of file names to read values from.

Paths(...string)

Provide a list of paths to search for files with values.

Overload()

This is a Load() only option.

Replace any existing values that either were already set in the environment variables or were set from a previously read file.

RequiredKeys(...string)

This is a Load() only option.

Provides a list of keys that will be checked just before Load() is done. If any of the keys are not set in the environment then Load() will return an error message listing all missing keys.

AllFilesRequired()

This will cause either Load() or Parse() to return an error when the first missing file is encountered.

EnvironmentFiles(string)

Sets a group of files using the given environment name.

environment	Result
test	.env.test.local, .env.test, .env
anything else	.env.<environment>.local, .env.local, .env.<environment>, .env

Using Options

You can pass in any combination of options you need to either Load() or Parse().

err := dotenv.Load(
        dotenv.EnvironmentFiles(os.Getenv("MY_APP_ENV")),
        dotenv.RequireKeys("DATABASE_URL", "HOST", "LOG_LEVEL"),
    )

// the same goes for Parse()

Autoload

There is an autoload as well if you do not need to make use of any of the options.

package main

import (
	_ "github.com/stackus/dotenv/autoload"
)

func main() {
    // values have already been loaded
}

CLI

You can also use this library in the CLI to execute applications with modified environments.

Installation

go install github.com/stackus/dotenv/cmd/dotenv@latest

Usage

Prefix the command with a call to dotenv first along with some arguments to load the file or files you need, such as:

dotenv -f .env -f .other-env -- your-command -a your-args

In the above example dotenv was used to load values into the environment from two different files, then the command your-command and its arguments followed a split, identified as --.

Use -- to signal when the dotenv flag parser should stop. Everything to the right of it will be left unparsed and used as the command that will be run along with any arguments that may also exist.

The dotenv command will also accept the -e flag to set the environment which works like the EnvironmentFiles(env) option above, as well as the -p flag to provide one or more paths. -p may be repeated just like -f.

Similarities with the Ruby version

Nearly everything the Ruby version would parse is parsed in this version. With one major difference. There is no command substitution.

# start simple and go from there
FOO=bar             # bar
FOO1=bar#baz        # bar#baz
FOO2=fizz buzz      # fizz buzz
FOO3="bar"          # bar
FOO4= "bar"         # bar
FOO5 = "bar"        # bar
FOO6="foo$FOO5"     # foobar
FOO7="foo\$FOO5"    # foo$FOO5
FOO8="a multi
line value"         # a multi\nline value
BAR1='foo'          # foo
BAR2='bar$BAR1'     # bar$BAR1
BAR3: yaml-like     # yaml-like
export BAR4=bar     # bar
export UNDEFINED    # this will return a warning error just as the Ruby version does

It also doesn't parse "FOO=foo\rBAR=bar" (strings that use only a carriage return) correctly.

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request