add config

config/source/env/watcher.go

@@ -0,0 +1,26 @@
+package env
+
+import (
+	"errors"
+
+	"github.com/micro/go-micro/config/source"
+)
+
+type watcher struct {
+	exit chan struct{}
+}
+
+func (w *watcher) Next() (*source.ChangeSet, error) {
+	<-w.exit
+
+	return nil, errors.New("watcher stopped")
+}
+
+func (w *watcher) Stop() error {
+	close(w.exit)
+	return nil
+}
+
+func newWatcher() (source.Watcher, error) {
+	return &watcher{exit: make(chan struct{})}, nil
+}