Move shim package to pkg

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

pkg/shim/publisher.go

@@ -0,0 +1,170 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package shim
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	v1 "github.com/containerd/containerd/v2/api/services/ttrpc/events/v1"
+	"github.com/containerd/containerd/v2/api/types"
+	"github.com/containerd/containerd/v2/core/events"
+	"github.com/containerd/containerd/v2/pkg/namespaces"
+	"github.com/containerd/containerd/v2/pkg/ttrpcutil"
+	"github.com/containerd/containerd/v2/protobuf"
+	"github.com/containerd/log"
+	"github.com/containerd/ttrpc"
+)
+
+const (
+	queueSize  = 2048
+	maxRequeue = 5
+)
+
+type item struct {
+	ev    *types.Envelope
+	ctx   context.Context
+	count int
+}
+
+// NewPublisher creates a new remote events publisher
+func NewPublisher(address string) (*RemoteEventsPublisher, error) {
+	client, err := ttrpcutil.NewClient(address)
+	if err != nil {
+		return nil, err
+	}
+
+	l := &RemoteEventsPublisher{
+		client:  client,
+		closed:  make(chan struct{}),
+		requeue: make(chan *item, queueSize),
+	}
+
+	go l.processQueue()
+	return l, nil
+}
+
+// RemoteEventsPublisher forwards events to a ttrpc server
+type RemoteEventsPublisher struct {
+	client  *ttrpcutil.Client
+	closed  chan struct{}
+	closer  sync.Once
+	requeue chan *item
+}
+
+// Done returns a channel which closes when done
+func (l *RemoteEventsPublisher) Done() <-chan struct{} {
+	return l.closed
+}
+
+// Close closes the remote connection and closes the done channel
+func (l *RemoteEventsPublisher) Close() (err error) {
+	err = l.client.Close()
+	l.closer.Do(func() {
+		close(l.closed)
+	})
+	return err
+}
+
+func (l *RemoteEventsPublisher) processQueue() {
+	for i := range l.requeue {
+		if i.count > maxRequeue {
+			log.L.Errorf("evicting %s from queue because of retry count", i.ev.Topic)
+			// drop the event
+			continue
+		}
+
+		if err := l.forwardRequest(i.ctx, &v1.ForwardRequest{Envelope: i.ev}); err != nil {
+			log.L.WithError(err).Error("forward event")
+			l.queue(i)
+		}
+	}
+}
+
+func (l *RemoteEventsPublisher) queue(i *item) {
+	go func() {
+		i.count++
+		// re-queue after a short delay
+		time.Sleep(time.Duration(1*i.count) * time.Second)
+		l.requeue <- i
+	}()
+}
+
+// Publish publishes the event by forwarding it to the configured ttrpc server
+func (l *RemoteEventsPublisher) Publish(ctx context.Context, topic string, event events.Event) error {
+	ns, err := namespaces.NamespaceRequired(ctx)
+	if err != nil {
+		return err
+	}
+	evt, err := protobuf.MarshalAnyToProto(event)
+	if err != nil {
+		return err
+	}
+	i := &item{
+		ev: &types.Envelope{
+			Timestamp: protobuf.ToTimestamp(time.Now()),
+			Namespace: ns,
+			Topic:     topic,
+			Event:     evt,
+		},
+		ctx: ctx,
+	}
+
+	if err := l.forwardRequest(i.ctx, &v1.ForwardRequest{Envelope: i.ev}); err != nil {
+		l.queue(i)
+		return err
+	}
+
+	return nil
+}
+
+func (l *RemoteEventsPublisher) forwardRequest(ctx context.Context, req *v1.ForwardRequest) error {
+	service, err := l.client.EventsService()
+	if err == nil {
+		fCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
+		_, err = service.Forward(fCtx, req)
+		cancel()
+		if err == nil {
+			return nil
+		}
+	}
+
+	if err != ttrpc.ErrClosed {
+		return err
+	}
+
+	// Reconnect and retry request
+	if err = l.client.Reconnect(); err != nil {
+		return err
+	}
+
+	service, err = l.client.EventsService()
+	if err != nil {
+		return err
+	}
+
+	// try again with a fresh context, otherwise we may get a context timeout unexpectedly.
+	fCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
+	_, err = service.Forward(fCtx, req)
+	cancel()
+	if err != nil {
+		return err
+	}
+
+	return nil
+}