github.com/containerd/containerd@v22.0.0-20200918172823-438c87b8e050+incompatible/pkg/ttrpcutil/client.go (about)

     1  /*
     2     Copyright The containerd Authors.
     3  
     4     Licensed under the Apache License, Version 2.0 (the "License");
     5     you may not use this file except in compliance with the License.
     6     You may obtain a copy of the License at
     7  
     8         http://www.apache.org/licenses/LICENSE-2.0
     9  
    10     Unless required by applicable law or agreed to in writing, software
    11     distributed under the License is distributed on an "AS IS" BASIS,
    12     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13     See the License for the specific language governing permissions and
    14     limitations under the License.
    15  */
    16  
    17  package ttrpcutil
    18  
    19  import (
    20  	"sync"
    21  	"time"
    22  
    23  	v1 "github.com/containerd/containerd/api/services/ttrpc/events/v1"
    24  	"github.com/containerd/containerd/pkg/dialer"
    25  	"github.com/containerd/ttrpc"
    26  	"github.com/pkg/errors"
    27  )
    28  
    29  const ttrpcDialTimeout = 5 * time.Second
    30  
    31  type ttrpcConnector func() (*ttrpc.Client, error)
    32  
    33  // Client is the client to interact with TTRPC part of containerd server (plugins, events)
    34  type Client struct {
    35  	mu        sync.Mutex
    36  	connector ttrpcConnector
    37  	client    *ttrpc.Client
    38  	closed    bool
    39  }
    40  
    41  // NewClient returns a new containerd TTRPC client that is connected to the containerd instance provided by address
    42  func NewClient(address string, opts ...ttrpc.ClientOpts) (*Client, error) {
    43  	connector := func() (*ttrpc.Client, error) {
    44  		conn, err := dialer.Dialer(address, ttrpcDialTimeout)
    45  		if err != nil {
    46  			return nil, errors.Wrap(err, "failed to connect")
    47  		}
    48  
    49  		client := ttrpc.NewClient(conn, opts...)
    50  		return client, nil
    51  	}
    52  
    53  	return &Client{
    54  		connector: connector,
    55  	}, nil
    56  }
    57  
    58  // Reconnect re-establishes the TTRPC connection to the containerd daemon
    59  func (c *Client) Reconnect() error {
    60  	c.mu.Lock()
    61  	defer c.mu.Unlock()
    62  
    63  	if c.connector == nil {
    64  		return errors.New("unable to reconnect to containerd, no connector available")
    65  	}
    66  
    67  	if c.closed {
    68  		return errors.New("client is closed")
    69  	}
    70  
    71  	if c.client != nil {
    72  		if err := c.client.Close(); err != nil {
    73  			return err
    74  		}
    75  	}
    76  
    77  	client, err := c.connector()
    78  	if err != nil {
    79  		return err
    80  	}
    81  
    82  	c.client = client
    83  	return nil
    84  }
    85  
    86  // EventsService creates an EventsService client
    87  func (c *Client) EventsService() (v1.EventsService, error) {
    88  	client, err := c.Client()
    89  	if err != nil {
    90  		return nil, err
    91  	}
    92  	return v1.NewEventsClient(client), nil
    93  }
    94  
    95  // Client returns the underlying TTRPC client object
    96  func (c *Client) Client() (*ttrpc.Client, error) {
    97  	c.mu.Lock()
    98  	defer c.mu.Unlock()
    99  	if c.client == nil {
   100  		client, err := c.connector()
   101  		if err != nil {
   102  			return nil, err
   103  		}
   104  		c.client = client
   105  	}
   106  	return c.client, nil
   107  }
   108  
   109  // Close closes the clients TTRPC connection to containerd
   110  func (c *Client) Close() error {
   111  	c.mu.Lock()
   112  	defer c.mu.Unlock()
   113  
   114  	c.closed = true
   115  	if c.client != nil {
   116  		return c.client.Close()
   117  	}
   118  	return nil
   119  }