Paerser
Features
Loads configuration from many sources:
- CLI flags
- Configuration files in YAML, TOML, JSON format
- Environment variables
It also provides a simple CLI commands handling system.
Examples
Configuration
CLI Flags
package flag_test
import (
"log"
"github.com/davecgh/go-spew/spew"
"github.com/traefik/paerser/flag"
)
type ConfigExample struct {
Foo string
Bar Bar
Great bool
}
type Bar struct {
Sub *Sub
List []string
}
type Sub struct {
Name string
Value int
}
func ExampleDecode() {
args := []string{
"--foo=aaa",
"--great=true",
"--bar.list=AAA,BBB",
"--bar.sub.name=bbb",
"--bar.sub.value=6",
}
config := ConfigExample{}
err := flag.Decode(args, &config)
if err != nil {
log.Fatal(err)
}
spew.Config = spew.ConfigState{
Indent: "\t",
DisablePointerAddresses: true,
}
spew.Dump(config)
// Output:
// (flag_test.ConfigExample) {
// Foo: (string) (len=3) "aaa",
// Bar: (flag_test.Bar) {
// Sub: (*flag_test.Sub)({
// Name: (string) (len=3) "bbb",
// Value: (int) 6
// }),
// List: ([]string) (len=2 cap=2) {
// (string) (len=3) "AAA",
// (string) (len=3) "BBB"
// }
// },
// Great: (bool) true
// }
}File
package file_test
import (
"fmt"
"log"
"os"
"github.com/davecgh/go-spew/spew"
"github.com/traefik/paerser/file"
)
type ConfigExample struct {
Foo string
Bar Bar
Great bool
}
type Bar struct {
Sub *Sub
List []string
}
type Sub struct {
Name string
Value int
}
func ExampleDecode() {
tempFile, err := os.CreateTemp("", "paeser-*.yml")
if err != nil {
log.Fatal(err)
}
defer func() { _ = os.RemoveAll(tempFile.Name()) }()
data := `
foo: aaa
bar:
sub:
name: bbb
value: 6
list:
- AAA
- BBB
great: true
`
_, err = fmt.Fprint(tempFile, data)
if err != nil {
log.Fatal(err)
}
// Read configuration file
filePath := tempFile.Name()
config := ConfigExample{}
err = file.Decode(filePath, &config)
if err != nil {
log.Fatal(err)
}
spew.Config = spew.ConfigState{
Indent: "\t",
DisablePointerAddresses: true,
}
spew.Dump(config)
// Output:
// (file_test.ConfigExample) {
// Foo: (string) (len=3) "aaa",
// Bar: (file_test.Bar) {
// Sub: (*file_test.Sub)({
// Name: (string) (len=3) "bbb",
// Value: (int) 6
// }),
// List: ([]string) (len=2 cap=2) {
// (string) (len=3) "AAA",
// (string) (len=3) "BBB"
// }
// },
// Great: (bool) true
// }
}Environment Variables
package env_test
import (
"log"
"os"
"github.com/davecgh/go-spew/spew"
"github.com/traefik/paerser/env"
)
type ConfigExample struct {
Foo string
Bar Bar
Great bool
}
type Bar struct {
Sub *Sub
List []string
}
type Sub struct {
Name string
Value int
}
func ExampleDecode() {
_ = os.Setenv("MYAPP_FOO", "aaa")
_ = os.Setenv("MYAPP_GREAT", "true")
_ = os.Setenv("MYAPP_BAR_LIST", "AAA,BBB")
_ = os.Setenv("MYAPP_BAR_SUB_NAME", "bbb")
_ = os.Setenv("MYAPP_BAR_SUB_VALUE", "6")
config := ConfigExample{}
err := env.Decode(os.Environ(), "MYAPP_", &config)
if err != nil {
log.Fatal(err)
}
spew.Config = spew.ConfigState{
Indent: "\t",
DisablePointerAddresses: true,
}
spew.Dump(config)
// Output:
// (env_test.ConfigExample) {
// Foo: (string) (len=3) "aaa",
// Bar: (env_test.Bar) {
// Sub: (*env_test.Sub)({
// Name: (string) (len=3) "bbb",
// Value: (int) 6
// }),
// List: ([]string) (len=2 cap=2) {
// (string) (len=3) "AAA",
// (string) (len=3) "BBB"
// }
// },
// Great: (bool) true
// }
}CLI Commands
TODO