https://github.com/amenzhinsky/flagenv

Environment variables support for the snadard flag package.
https://github.com/amenzhinsky/flagenv

cli command-line environment-variables go golang

Last synced: 2 days ago
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Environment variables support for the snadard flag package.

• Host: GitHub
• URL: https://github.com/amenzhinsky/flagenv
• Owner: amenzhinsky
• License: mit
• Created: 2019-05-30T11:38:22.000Z (over 5 years ago)
• Default Branch: master
• Last Pushed: 2020-03-27T19:01:36.000Z (over 4 years ago)
• Last Synced: 2024-06-20T19:19:04.270Z (5 months ago)
• Topics: cli, command-line, environment-variables, go, golang
• Language: Go
• Homepage:
• Size: 21.5 KB
• Stars: 1
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# flagenv

Environment variables support for the standard `flag` package.

## Usage

The library helps to reduce amount of code usually written to use environment variables as fallbacks for command-line options.

Simply replace `flag.Parse()` in your main application with `flagenv.Parse()` to add the functionality (the module also supports passing `*flag.FlagSet` to `flagenv.ParseWithEnv` for lower-level usage).

Environment is only applied to the flags that are not set through the command-line arguments.

Environment variable names are added to each flag in the help message:

```

Usage of main:

  -timeout uint

        connection timeout [$TIMEOUT] (default 10)

```

## Configuration

In case you're using short flag names you may employ `WithMap` option to override environment variable names with more descriptive alternatives:

```go

flag.StringVar(&addrFlag, "a", ":8080", "address to connect to")

flag.UintVar(&timeoutFlag, "t", 0, "connection timeout")

flag.BoolVar(&forceFlag, "f", false, "force the action")

flagenv.Parse(flagenv.WithMap(func(name string) string {

	switch name {

	case "a":

		return "ADDR"

	case "t":

		return "TIMEOUT"

	case "f":

		// ignore '-f' flag

		return "" 

	default:

		// fall back to the default behaviour

		return flagenv.DefaultMap(name)

	}

}))

```

## Contributing

All contributions are welcome. Please fill in an issue before submitting pull requests.