# initialize struct from environment variables

This is a very straightforward library; it initializes each exported field in a struct from an environment variable. Usage:

```go
import "go.vedthiru.com/envstruct"

type logOpts struct {
	File    string `envDefault:"./log"`
	UseJSON bool
}
type testStruct struct {
	Port    uint
	BufSize uint
	Log     logOpts
	Custom  string `envVar:"MY_VAR"`
	IP      net.IP
}

func main() {
  var c config
  err := envstruct.Parse("MY_APP", &c)
}
```

- If a field doesn't have the tag `envVar`, `Parse` reads the value from an appropriate corresponding environment variable. If the struct is nested, the names of the intermediate fields are added. For example, `UseJSON` above is read from `MY_APP_LOG_USE_JSON`.
- *envstruct* supports parsing `string`s, `uint`s, `bool`s, and any type that implements [`encoding.TextUnmarshaler`](https://pkg.go.dev/encoding#TextUnmarshaler).
- *envstruct* will only handle fields exported from the struct (just like `encoding/json` and `encoding/xml`).
- If a field does not have the `envDefault` struct tag, and the environment variable is not defined, `Parse` will return an error.