Merge pull request #36630 from AkihiroSuda/hijack-dialer

client: add WithDialContext() and client.Dialer()

client/client.go

@@ -173,10 +173,17 @@ func WithTLSClientConfig(cacertPath, certPath, keyPath string) func(*Client) err
 
 // WithDialer applies the dialer.DialContext to the client transport. This can be
 // used to set the Timeout and KeepAlive settings of the client.
+// Deprecated: use WithDialContext
 func WithDialer(dialer *net.Dialer) func(*Client) error {
+	return WithDialContext(dialer.DialContext)
+}
+
+// WithDialContext applies the dialer to the client transport. This can be
+// used to set the Timeout and KeepAlive settings of the client.
+func WithDialContext(dialContext func(ctx context.Context, network, addr string) (net.Conn, error)) func(*Client) error {
 	return func(c *Client) error {
 		if transport, ok := c.client.Transport.(*http.Transport); ok {
-			transport.DialContext = dialer.DialContext
+			transport.DialContext = dialContext
 			return nil
 		}
 		return errors.Errorf("cannot apply dialer to transport: %T", c.client.Transport)
@@ -400,3 +407,16 @@ func (cli *Client) CustomHTTPHeaders() map[string]string {
 func (cli *Client) SetCustomHTTPHeaders(headers map[string]string) {
 	cli.customHTTPHeaders = headers
 }
+
+// Dialer returns a dialer for a raw stream connection, with HTTP/1.1 header, that can be used for proxying the daemon connection.
+// Used by `docker dial-stdio` (docker/cli#889).
+func (cli *Client) Dialer() func(context.Context) (net.Conn, error) {
+	return func(ctx context.Context) (net.Conn, error) {
+		if transport, ok := cli.client.Transport.(*http.Transport); ok {
+			if transport.DialContext != nil {
+				return transport.DialContext(ctx, cli.proto, cli.addr)
+			}
+		}
+		return fallbackDial(cli.proto, cli.addr, resolveTLSConfig(cli.client.Transport))
+	}
+}

client/hijack.go

@@ -30,7 +30,7 @@ func (cli *Client) postHijacked(ctx context.Context, path string, query url.Valu
 	}
 	req = cli.addHeaders(req, headers)
 
-	conn, err := cli.setupHijackConn(req, "tcp")
+	conn, err := cli.setupHijackConn(ctx, req, "tcp")
 	if err != nil {
 		return types.HijackedResponse{}, err
 	}
@@ -38,7 +38,9 @@ func (cli *Client) postHijacked(ctx context.Context, path string, query url.Valu
 	return types.HijackedResponse{Conn: conn, Reader: bufio.NewReader(conn)}, err
 }
 
-func dial(proto, addr string, tlsConfig *tls.Config) (net.Conn, error) {
+// fallbackDial is used when WithDialer() was not called.
+// See cli.Dialer().
+func fallbackDial(proto, addr string, tlsConfig *tls.Config) (net.Conn, error) {
 	if tlsConfig != nil && proto != "unix" && proto != "npipe" {
 		return tls.Dial(proto, addr, tlsConfig)
 	}
@@ -48,12 +50,13 @@ func dial(proto, addr string, tlsConfig *tls.Config) (net.Conn, error) {
 	return net.Dial(proto, addr)
 }
 
-func (cli *Client) setupHijackConn(req *http.Request, proto string) (net.Conn, error) {
+func (cli *Client) setupHijackConn(ctx context.Context, req *http.Request, proto string) (net.Conn, error) {
 	req.Host = cli.addr
 	req.Header.Set("Connection", "Upgrade")
 	req.Header.Set("Upgrade", proto)
 
-	conn, err := dial(cli.proto, cli.addr, resolveTLSConfig(cli.client.Transport))
+	dialer := cli.Dialer()
+	conn, err := dialer(ctx)
 	if err != nil {
 		return nil, errors.Wrap(err, "cannot connect to the Docker daemon. Is 'docker daemon' running on this host?")
 	}

client/interface.go

@@ -39,6 +39,7 @@ type CommonAPIClient interface {
 	NegotiateAPIVersion(ctx context.Context)
 	NegotiateAPIVersionPing(types.Ping)
 	DialSession(ctx context.Context, proto string, meta map[string][]string) (net.Conn, error)
+	Dialer() func(context.Context) (net.Conn, error)
 	Close() error
 }
 

client/session.go

@@ -14,5 +14,5 @@ func (cli *Client) DialSession(ctx context.Context, proto string, meta map[strin
 	}
 	req = cli.addHeaders(req, meta)
 
-	return cli.setupHijackConn(req, proto)
+	return cli.setupHijackConn(ctx, req, proto)
 }