Move ttrpc client to pkg/ttrpcutil

Signed-off-by: Maksym Pavlenko <makpav@amazon.com>

pkg/ttrpcutil/client.go

@@ -0,0 +1,105 @@
+/*
+   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 ttrpcutil
+
+import (
+	"sync"
+	"time"
+
+	v1 "github.com/containerd/containerd/api/services/ttrpc/events/v1"
+	"github.com/containerd/ttrpc"
+	"github.com/pkg/errors"
+)
+
+const ttrpcDialTimeout = 5 * time.Second
+
+type ttrpcConnector func() (*ttrpc.Client, error)
+
+// Client is the client to interact with TTRPC part of containerd server (plugins, events)
+type Client struct {
+	mu        sync.Mutex
+	connector ttrpcConnector
+	client    *ttrpc.Client
+	closed    bool
+}
+
+// NewClient returns a new containerd TTRPC client that is connected to the containerd instance provided by address
+func NewClient(address string, opts ...ttrpc.ClientOpts) (*Client, error) {
+	connector := func() (*ttrpc.Client, error) {
+		conn, err := ttrpcDial(address, ttrpcDialTimeout)
+		if err != nil {
+			return nil, errors.Wrap(err, "failed to connect")
+		}
+
+		client := ttrpc.NewClient(conn, opts...)
+		return client, nil
+	}
+
+	client, err := connector()
+	if err != nil {
+		return nil, err
+	}
+
+	return &Client{
+		connector: connector,
+		client:    client,
+	}, nil
+}
+
+// Reconnect re-establishes the TTRPC connection to the containerd daemon
+func (c *Client) Reconnect() error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.connector == nil {
+		return errors.New("unable to reconnect to containerd, no connector available")
+	}
+
+	if c.closed {
+		return errors.New("client is closed")
+	}
+
+	client, err := c.connector()
+	if err != nil {
+		return err
+	}
+
+	c.client = client
+	return nil
+}
+
+// EventsService creates an EventsService client
+func (c *Client) EventsService() v1.EventsService {
+	return v1.NewEventsClient(c.Client())
+}
+
+// Client returns the underlying TTRPC client object
+func (c *Client) Client() *ttrpc.Client {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	return c.client
+}
+
+// Close closes the clients TTRPC connection to containerd
+func (c *Client) Close() error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.closed = true
+	return c.client.Close()
+}