https://github.com/ofw/goenvconfig
Unmarshal env into struct to use as config in Golang; pretty print results too.
https://github.com/ofw/goenvconfig
configuration environment-variables golang
Last synced: over 1 year ago
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Unmarshal env into struct to use as config in Golang; pretty print results too.
- Host: GitHub
- URL: https://github.com/ofw/goenvconfig
- Owner: ofw
- License: mit
- Created: 2020-06-15T16:22:09.000Z (about 6 years ago)
- Default Branch: master
- Last Pushed: 2020-06-15T18:56:43.000Z (about 6 years ago)
- Last Synced: 2025-01-25T17:10:21.570Z (over 1 year ago)
- Topics: configuration, environment-variables, golang
- Language: Go
- Homepage:
- Size: 16.6 KB
- Stars: 2
- Watchers: 2
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# envconfig
[](https://goreportcard.com/report/github.com/ofw/goenvconfig)
[](https://godoc.org/github.com/ofw/goenvconfig/envconfig)
[](https://pkg.go.dev/github.com/ofw/goenvconfig/envconfig)
```Go
import "github.com/ofw/goenvconfig/envconfig"
```
## Goals
This library was inspired by [envconfig](https://github.com/kelseyhightower/envconfig) with some goals in mind:
1. Simplicity:
- only flat structure of config. so mapping env variables to fields is obvious.
- no guessing of env variable names. just case sensitive match.
- all env variables are required to be set. support default values
2. Observability:
- supports pretty printing results of parsing env variables to struct
3. User-friendliness:
- supports ability to pretty print results of unmarshaling env variables to config
## Usage
Set some environment variables:
```Bash
export MYAPP_DEBUG=false
export MYAPP_PORT=8080
export MYAPP_USER=Kelsey
export MYAPP_RATE="0.5"
export MYAPP_TIMEOUT="3m"
export MYAPP_USERS="rob,ken,robert"
export MYAPP_COLOR_CODES="red:1,green:2,blue:3"
```
Write some code:
```Go
package main
import (
"fmt"
"time"
"github.com/ofw/goenvconfig/envconfig"
)
func main() {
var s struct {
Debug bool `env:"MYAPP_DEBUG"`
Port int `env:"MYAPP_PORT"`
User string `env:"MYAPP_USER"`
Users []string `env:"MYAPP_USERS"`
Rate float32 `env:"MYAPP_RATE"`
Timeout time.Duration `env:"MYAPP_TIMEOUT"`
ColorCodes map[string]int `env:"MYAPP_COLOR_CODES"`
}
results, err := envconfig.Unmarshal(&s)
results.PrettyPrint() // it is nil safe
// Env Variable Type OK
// ---- ---- ----
// MYAPP_COLOR_CODES map[string]int v
// MYAPP_DEBUG bool v
// MYAPP_PORT int v
// MYAPP_RATE float32 v
// MYAPP_TIMEOUT time.Duration v
// MYAPP_USER string v
// MYAPP_USERS []string v
fmt.Printf("%+v", s)
// Result:
// {
// Debug:false
// Port:8080 User:Kelsey
// Users:[rob ken robert]
// Rate:0.5
// Timeout:3m0s
// ColorCodes:map[blue:3 green:2 red:1]
// }
}
```
## Struct Tag Support
Env variable name must be specified using `env` tag.
If struct contains field without `env` tag that will result in error.
Environment variables are required by default.
If this is not desired one can use a `default` tag to specify value
in case environment variable is not set.
For example, consider the following struct:
```Go
type Specification struct {
Default string `env:"MYAPP_DEFAULT" default:"foobar"`
Foo string `env:"MYAPP_FOO"`
}
```
If envconfig can't find an environment variable `MYAPP_DEFAULT`
it will populate it with "foobar" as a default value.
If envconfig can't find an environment variable `MYAPP_FOO` it will return an error.
## Supported Struct Field Types
envconfig supports these struct field types:
* string
* int8, int16, int32, int64
* bool
* float32, float64
* slices of any supported type
* maps (keys and values of any supported type)
* [encoding.TextUnmarshaler](https://golang.org/pkg/encoding/#TextUnmarshaler)
* [encoding.BinaryUnmarshaler](https://golang.org/pkg/encoding/#BinaryUnmarshaler)
* [time.Duration](https://golang.org/pkg/time/#Duration)
Embedded structs using these fields are also supported.
## Custom Decoders
Any field whose type (or pointer-to-type) implements `envconfig.Decoder` can
control its own deserialization:
```Bash
export DNS_SERVER=8.8.8.8
```
```Go
type IPDecoder net.IP
func (ipd *IPDecoder) Decode(value string) error {
*ipd = IPDecoder(net.ParseIP(value))
return nil
}
type DNSConfig struct {
Address IPDecoder `env:"DNS_SERVER"`
}
```
Also, envconfig will use a `Set(string) error` method like from the
[flag.Value](https://godoc.org/flag#Value) interface if implemented.