add all the plugins

plugins/config/source/runtimevar/watcher.go

@@ -0,0 +1,78 @@
+package runtimevar
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"github.com/micro/go-micro/v2/config/source"
+	"gocloud.dev/runtimevar"
+)
+
+type watcher struct {
+	name string
+	opts source.Options
+	exit chan bool
+	v    *runtimevar.Variable
+}
+
+func (w *watcher) Next() (*source.ChangeSet, error) {
+	// check exit status
+	select {
+	case <-w.exit:
+		return nil, errors.New("watcher stopped")
+	default:
+	}
+
+	// create a context with cancellation to kill watcher
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	go func() {
+		// if the watcher stops then cancel
+		select {
+		case <-w.exit:
+			cancel()
+		}
+	}()
+
+	s, err := w.v.Watch(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	// assuming value is bytes
+	b, err := w.opts.Encoder.Encode(s.Value.([]byte))
+	if err != nil {
+		return nil, fmt.Errorf("error reading source: %v", err)
+	}
+
+	cs := &source.ChangeSet{
+		Timestamp: s.UpdateTime,
+		Format:    w.opts.Encoder.String(),
+		Source:    w.name,
+		Data:      b,
+	}
+	cs.Checksum = cs.Sum()
+
+	return cs, nil
+}
+
+func (w *watcher) Stop() error {
+	select {
+	case <-w.exit:
+		return nil
+	default:
+		close(w.exit)
+		return nil
+	}
+}
+
+func newWatcher(name string, v *runtimevar.Variable, opts source.Options) (source.Watcher, error) {
+	return &watcher{
+		name: name,
+		opts: opts,
+		exit: make(chan bool),
+		v:    v,
+	}, nil
+}