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Go support library to aide and enhance using environment variables for configuration

env 최신버젼 다운로드

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# env

Go support library to aide and enhance using environment variables for configuration.

Please see [the examples directory](examples/) for inspiration. API Documentation is available [here](http://godoc.org/github.com/danryan/env).

## Getting started

### Example

```go
package main

import (
  "github.com/danryan/env"
  "fmt"
  "os"
)

// An imaginary config for a chat bot
type Config struct {
  Name    string `env:"key=NAME required=true"`
  Port    int    `env:"key=PORT default=9000"`
  Adapter string `env:"key=ADAPTER default=shell in=shell,slack,hipchat"`
  Enabled bool   `env:"key=IS_ENABLED default=true"`
}

func main() {
  os.Setenv("NAME", "hal")
  c := &Config{}
  if err := env.Process(c); err != nil {
    fmt.Println(err)
  }
  fmt.Printf("name: %s, port: %d, adapter: %s, enabled: %v\n", c.Name, c.Port, c.Adapter, c.Enabled)
}
// Will print out
// name: foo, port: 9001, adapter: shell, enabled: true
```

This library uses runtime reflection just like `encoding/json`. Most programs won't have more than a handful of config objects, so the slowness typically associated with reflection is negligible here.

### Supported types

Four types are currently supported:

* `string` - defaults to `""`
* `int` - defaults to `0`
* `bool` - defaults to `false`
* `float64` - defaults to `0.0`

Support for custom types via interfaces will likely make an an appearance at a later date.

### Struct tags

Env uses struct tags to set up rules for parsing environment variables and setting fields on your config struct. Tag syntax must be either `key=value` or `key` (boolean), using spaces to separate. Spaces in keys or values are not allowed. This is very likely to change in the future, as it's a rather limiting restriction.

#### `key`

The key is used to look up an environment variable. Keys are automatically `UPPER_CASED`. If this tag is not specified, the name of the struct field will be used.

```go
// Look for a variable `MY_NAME`, or return an empty string
type Config struct {
  Name string `env:"key=MY_NAME"`
}

// Look for a variable `MY_PORT`. Note that uppercase conversion is automatic.
type Config struct {
  Port string `env:"key=my_port"`
}
```

#### `required`

Including `required` validates that the requested environment variable is present, or returns an error if not.

```go
// Look for a variable `NAME`, or return an error if not found.
type Config struct {
  Name string `env:"required"`
}
```

#### `default`

If specified, the default will be used if no environment variable is found matching the key. Default values must be castable to the associated struct field type, otherwise an error is returned.

```go
// Look for a variable `ENABLED` or otherwise default to true
type Config struct {
  Enabled bool `env:"default=true"`
}
config := &Config{}
if config.Enabled {
  fmt.Println("Enabled!") // prints "Enabled!"
}

// ...

// Look for a variable `NAME` or default to "Inigo"
type Config struct {
  Name string `env:"default=Inigo"`
}

config := &Config{}
fmt.Println(config.Name) // prints "Inigo"
```

#### `options`

Options ensure that an environment variable is in a set of possible valid values. If it is not, an error is returned.

```go
// Look for a variable `ADAPTER` and return an error if the variable is not
// included in the options
type Config struct {
  Adapter string `env:"options=shell,slack,hipchat"`
}
```

## Is it any good?

[Probably not.](http://news.ycombinator.com/item?id=3067434)

## Bugs, features, rants, etc.

Please use (the issue tracker)[https://github.com/danryan/env/issues) for development progress tracking, feature requests, or bug reports. Thank you! :heart:

env

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