For a given struct, builds a set of urfave/cli commands which allows you to modify it from the command line.
Useful for generating command line clients for your application configuration that is stored in a Go struct.
- Nested struct support
- Enum/Custom complex type support via MarshalText/UnmarshalText
- Slice support, including complex types
- Slice indexing by struct field
- Map support
- Default primitive value support when adding items to slices
- Adding new struct to a slice only allows setting primitive fields (use add-json as a work-around)
- Only primitive types supported for map keys and values
- No defaults for maps
Example config
type Config struct {
Address string `usage:"Address on which to listen"` // Description printed in -help
AuthMode AuthMode // Enum support
ThreadingOptions ThreadingOptions // Nested struct support
Backends []Backend // Slice support
EnvVars map[string]string // Map support
}
type Backend struct {
Hostname string `recli:"id"` // Constructs commands for indexing into the array based on the value of this field
Port int `default:"2019"` // Default support
BackoffIntervals []int `default:"10,20"` // Slice default support
IPAddressCached net.IP `recli:"-" json:"-"` // Skips the field
}
type ThreadingOptions struct {
MaxThreads int
}Sample input data
{
"Address":"http://website.com",
"AuthMode":"static",
"ThreadingOptions":{
"MaxThreads":10
},
"Backends":[
{
"Hostname":"backend1.com",
"Port":1010
},
{
"Hostname":"backend2.com",
"Port":2020
}
],
"EnvVars":{
"CC":"/usr/bin/gcc"
}
}Full example code
package main
import (
"encoding/json"
"fmt"
"net"
"os"
"github.com/AudriusButkevicius/recli"
"github.com/urfave/cli"
)
type Config struct {
Address string `usage:"Address on which to listen"` // Description printed in -help
AuthMode AuthMode // Enum support
ThreadingOptions ThreadingOptions // Nested struct support
Backends []Backend // Slice support
EnvVars map[string]string // Map support
}
type Backend struct {
Hostname string `recli:"id"` // Constructs commands for indexing into the array based on the value of this field
Port int `default:"2019"` // Default support
BackoffIntervals []int `default:"10,20"` // Slice default support
IPAddressCached net.IP `recli:"-" json:"-"` // Skips the field
}
type ThreadingOptions struct {
MaxThreads int
}
type AuthMode int
const (
AuthModeStatic AuthMode = iota // default is static
AuthModeLDAP
)
func (t AuthMode) MarshalText() ([]byte, error) {
switch t {
case AuthModeStatic:
return []byte("static"), nil
case AuthModeLDAP:
return []byte("ldap"), nil
}
return nil, fmt.Errorf("unknown value: %s", t)
}
func (t *AuthMode) UnmarshalText(bs []byte) error {
switch string(bs) {
case "ldap":
*t = AuthModeLDAP
case "static":
*t = AuthModeStatic
default:
return fmt.Errorf("unknown value: %s", string(bs))
}
return nil
}
const (
sampleData = `
{
"Address":"http://website.com",
"AuthMode":"static",
"ThreadingOptions":{
"MaxThreads":10
},
"Backends":[
{
"Hostname":"backend1.com",
"Port":1010
},
{
"Hostname":"backend2.com",
"Port":2020
}
],
"EnvVars":{
"CC":"/usr/bin/gcc"
}
}`
)
func main() {
cfg := &Config{}
if err := json.Unmarshal([]byte(sampleData), cfg); err != nil {
panic(err)
}
cmds, err := recli.Default.Construct(cfg)
if err != nil {
panic(err)
}
dump := false
app := cli.NewApp()
app.Commands = cmds
app.Flags = []cli.Flag{
cli.BoolFlag{
Name: "dump",
Destination: &dump,
},
}
if err := app.Run(os.Args); err != nil {
panic(err)
}
if dump {
bs, err := json.MarshalIndent(&cfg, "", " ")
if err != nil {
panic(err)
}
fmt.Print(string(bs))
}
}Get a field
$ go run main.go address get
http://website.comSet a field
$ go run main.go -dump address set foo
{
"Address": "foo",
"AuthMode": "static",
"ThreadingOptions": {
"MaxThreads": 10
},
"Backends": [
{
"Hostname": "backend1.com",
"Port": 1010,
"BackoffIntervals": null
},
{
"Hostname": "backend2.com",
"Port": 2020,
"BackoffIntervals": null
}
],
"EnvVars": {
"CC": "/usr/bin/gcc"
}
}Set a nested field
$ go run main.go -dump threading-options max-threads set 9500
{
"Address": "http://website.com",
"AuthMode": "static",
"ThreadingOptions": {
"MaxThreads": 9500
},
"Backends": [
{
"Hostname": "backend1.com",
"Port": 1010,
"BackoffIntervals": null
},
{
"Hostname": "backend2.com",
"Port": 2020,
"BackoffIntervals": null
}
],
"EnvVars": {
"CC": "/usr/bin/gcc"
}
}Listing available slice items (with a custom slice index key)
$ go run main.go backends
NAME:
main.exe backends -
USAGE:
main.exe backends command [command options] [arguments...]
COMMANDS:
ACTIONS:
add Add a new item to collection
add-json Add a new item to collection deserialised from JSON
ITEMS:
backend1.com
backend2.com
OPTIONS:
--help, -h show help
Deleting a slice item
$ go run main.go -dump backends backend1.com delete
{
"Address": "http://website.com",
"AuthMode": "static",
"ThreadingOptions": {
"MaxThreads": 10
},
"Backends": [
{
"Hostname": "backend2.com",
"Port": 2020,
"BackoffIntervals": null
}
],
"EnvVars": {
"CC": "/usr/bin/gcc"
}
}Adding a slice item (with defaults)
$ go run main.go -dump backends add -hostname="testback.end"
{
"Address": "http://website.com",
"AuthMode": "static",
"ThreadingOptions": {
"MaxThreads": 10
},
"Backends": [
{
"Hostname": "backend1.com",
"Port": 1010,
"BackoffIntervals": null
},
{
"Hostname": "backend2.com",
"Port": 2020,
"BackoffIntervals": null
},
{
"Hostname": "testback.end",
"Port": 2019,
"BackoffIntervals": [
10,
20
]
}
],
"EnvVars": {
"CC": "/usr/bin/gcc"
}
}Setting map keys
$ go run main.go -dump env-vars set GCC /usr/bin/true
{
"Address": "http://website.com",
"AuthMode": "static",
"ThreadingOptions": {
"MaxThreads": 10
},
"Backends": [
{
"Hostname": "backend1.com",
"Port": 1010,
"BackoffIntervals": null
},
{
"Hostname": "backend2.com",
"Port": 2020,
"BackoffIntervals": null
}
],
"EnvVars": {
"CC": "/usr/bin/gcc",
"GCC": "/usr/bin/true"
}
}