feat: add WithKey helper

config/remote/etcd/etcd.go

@@ -5,7 +5,9 @@ import (
 	"context"
 	"errors"
 	"fmt"
-
+	"github.com/DoNewsCode/core"
+	"github.com/DoNewsCode/core/config"
+	"github.com/DoNewsCode/core/contract"
 	"go.etcd.io/etcd/client/v3"
 )
 
@@ -17,13 +19,20 @@ type ETCD struct {
 }
 
 // Provider create a *ETCD
-func Provider(key string, clientConfig *clientv3.Config) *ETCD {
+func Provider(clientConfig *clientv3.Config, key string) *ETCD {
 	return &ETCD{
 		key:          key,
 		clientConfig: clientConfig,
 	}
 }
 
+// WithKey is a two-in-one coreOption. It uses the remote key on etcd as the
+// source of configuration, and watches the change of that key for hot reloading.
+func WithKey(cfg *clientv3.Config, key string, codec contract.Codec) (core.CoreOption, core.CoreOption) {
+	r := Provider(cfg, key)
+	return core.WithConfigStack(r, config.CodecParser{Codec: codec}), core.WithConfigWatcher(r)
+}
+
 // ReadBytes reads the contents of a key from etcd and returns the bytes.
 func (r *ETCD) ReadBytes() ([]byte, error) {
 	client, err := clientv3.New(*r.clientConfig)

config/remote/etcd/example_test.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"github.com/DoNewsCode/core"
 	"github.com/DoNewsCode/core/codec/yaml"
-	"github.com/DoNewsCode/core/config"
 	"github.com/DoNewsCode/core/config/remote/etcd"
 	clientv3 "go.etcd.io/etcd/client/v3"
 	"os"
@@ -21,23 +20,22 @@ func Example() {
 	}
 	key := "core.yaml"
 	envEtcdAddrs := strings.Split(addr, ",")
-	cfg := clientv3.Config{
+	cfg := &clientv3.Config{
 		Endpoints:   envEtcdAddrs,
 		DialTimeout: time.Second,
 	}
 	_ = put(cfg, key, "name: etcd")
 
-	provider := etcd.Provider(key, &cfg)
-	c := core.New(core.WithConfigStack(provider, config.CodecParser{Codec: yaml.Codec{}}), core.WithConfigWatcher(provider))
+	c := core.New(etcd.WithKey(cfg, key, yaml.Codec{}))
 	c.ProvideEssentials()
 	fmt.Println(c.String("name"))
 
 	// Output:
 	// etcd
 }
 
-func put(cfg clientv3.Config, key, val string) error {
-	client, err := clientv3.New(cfg)
+func put(cfg *clientv3.Config, key, val string) error {
+	client, err := clientv3.New(*cfg)
 	if err != nil {
 		return err
 	}