https://github.com/Netflix/go-env
a golang library to manage environment variables
https://github.com/Netflix/go-env
environment-variables golang
Last synced: 3 months ago
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a golang library to manage environment variables
- Host: GitHub
- URL: https://github.com/Netflix/go-env
- Owner: Netflix
- License: apache-2.0
- Created: 2018-05-22T00:01:45.000Z (almost 7 years ago)
- Default Branch: master
- Last Pushed: 2022-09-28T15:18:35.000Z (over 2 years ago)
- Last Synced: 2024-04-14T22:21:33.443Z (10 months ago)
- Topics: environment-variables, golang
- Language: Go
- Size: 56.6 KB
- Stars: 546
- Watchers: 292
- Forks: 56
- Open Issues: 7
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# go-env
[](https://pkg.go.dev/github.com/Netflix/go-env)
[]()
Package env provides an `env` struct field tag to marshal and unmarshal environment variables.
## Usage
```go
package main
import (
"log"
"time"
"github.com/Netflix/go-env"
)
type Environment struct {
Home string `env:"HOME"`
Jenkins struct {
BuildId *string `env:"BUILD_ID"`
BuildNumber int `env:"BUILD_NUMBER"`
Ci bool `env:"CI"`
}
Node struct {
ConfigCache *string `env:"npm_config_cache,NPM_CONFIG_CACHE"`
}
Extras env.EnvSet
Duration time.Duration `env:"TYPE_DURATION"`
DefaultValue string `env:"MISSING_VAR,default=default_value"`
RequiredValue string `env:"IM_REQUIRED,required=true"`
ArrayValue []string `env:"ARRAY_VALUE,default=value1|value2|value3"`
}
func main() {
var environment Environment
es, err := env.UnmarshalFromEnviron(&environment)
if err != nil {
log.Fatal(err)
}
// Remaining environment variables.
environment.Extras = es
// ...
es, err = env.Marshal(&environment)
if err != nil {
log.Fatal(err)
}
home := "/tmp/edgarl"
cs := env.ChangeSet{
"HOME": &home,
"BUILD_ID": nil,
"BUILD_NUMBER": nil,
}
es.Apply(cs)
environment = Environment{}
if err = env.Unmarshal(es, &environment); err != nil {
log.Fatal(err)
}
environment.Extras = es
}
```
This will initially throw an error if `IM_REQUIRED` is not set in the environment as part of the env struct validation.
This error can be resolved by setting the `IM_REQUIRED` environment variable manually in the environment or by setting it in the
code prior to calling `UnmarshalFromEnviron` with:
```go
os.Setenv("IM_REQUIRED", "some_value")
```
## Custom Marshaler/Unmarshaler
There is limited support for dictating how a field should be marshaled or unmarshaled. The following example
shows how you could marshal/unmarshal from JSON
```go
package main
import (
"encoding/json"
"fmt"
"log"
"github.com/Netflix/go-env"
)
type SomeData struct {
SomeField int `json:"someField"`
}
func (s *SomeData) UnmarshalEnvironmentValue(data string) error {
var tmp SomeData
if err := json.Unmarshal([]byte(data), &tmp); err != nil {
return err
}
*s = tmp
return nil
}
func (s SomeData) MarshalEnvironmentValue() (string, error) {
bytes, err := json.Marshal(s)
if err != nil {
return "", err
}
return string(bytes), nil
}
type Config struct {
SomeData *SomeData `env:"SOME_DATA"`
}
func main() {
var cfg Config
if _, err := env.UnmarshalFromEnviron(&cfg); err != nil {
log.Fatal(err)
}
if cfg.SomeData != nil && cfg.SomeData.SomeField == 42 {
fmt.Println("Got 42!")
} else {
fmt.Printf("Got nil or some other value: %v\n", cfg.SomeData)
}
es, err := env.Marshal(&cfg)
if err != nil {
log.Fatal(err)
}
fmt.Printf("Got the following: %+v\n", es)
}
```