plugin/etcdv3: Add etcd v3 plugin (#1702)

* Update dependencies and add etcdv3 client

* Update etcd plugin to support etcd v3 clients

Fixes #341

plugin/etcd/setup.go

@@ -11,7 +11,7 @@ import (
 	"github.com/coredns/coredns/plugin/pkg/upstream"
 	"github.com/coredns/coredns/plugin/proxy"
 
-	etcdc "github.com/coreos/etcd/client"
+	etcdcv3 "github.com/coreos/etcd/clientv3"
 	"github.com/mholt/caddy"
 )
 
@@ -124,22 +124,22 @@ func etcdParse(c *caddy.Controller) (*Etcd, bool, error) {
 		}
 		etc.Client = client
 		etc.endpoints = endpoints
-
+		
 		return &etc, stubzones, nil
 	}
 	return &Etcd{}, false, nil
 }
 
-func newEtcdClient(endpoints []string, cc *tls.Config) (etcdc.KeysAPI, error) {
-	etcdCfg := etcdc.Config{
+func newEtcdClient(endpoints []string, cc *tls.Config) (*etcdcv3.Client, error) {
+	etcdCfg := etcdcv3.Config{
 		Endpoints: endpoints,
-		Transport: mwtls.NewHTTPSTransport(cc),
+		TLS:       cc,
 	}
-	cli, err := etcdc.New(etcdCfg)
+	cli, err := etcdcv3.New(etcdCfg)
 	if err != nil {
 		return nil, err
 	}
-	return etcdc.NewKeysAPI(cli), nil
+	return cli, nil
 }
 
 const defaultEndpoint = "http://localhost:2379"