Merge pull request moby#3586 from marxarelli/review/client-session-connection-retry

buildctl: Provide --wait option

Author: tonistiigi

client/client.go

@@ -25,6 +25,7 @@ import (
 	sdktrace "go.opentelemetry.io/otel/sdk/trace"
 	"go.opentelemetry.io/otel/trace"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/credentials/insecure"
 )
@@ -184,6 +185,19 @@ func (c *Client) Dialer() session.Dialer {
 	return grpchijack.Dialer(c.ControlClient())
 }
 
+func (c *Client) Wait(ctx context.Context) error {
+	opts := []grpc.CallOption{grpc.WaitForReady(true)}
+	_, err := c.ControlClient().Info(ctx, &controlapi.InfoRequest{}, opts...)
+	if err != nil {
+		if code := grpcerrors.Code(err); code == codes.Unimplemented {
+			// only buildkit v0.11+ supports the info api, but an unimplemented
+			// response error is still a response so we can ignore it
+			return nil
+		}
+	}
+	return err
+}
+
 func (c *Client) Close() error {
 	return c.conn.Close()
 }

cmd/buildctl/common/common.go

@@ -90,10 +90,25 @@ func ResolveClient(c *cli.Context) (*client.Client, error) {
 	}
 
 	timeout := time.Duration(c.GlobalInt("timeout"))
-	ctx, cancel := context.WithTimeout(ctx, timeout*time.Second)
-	defer cancel()
+	if timeout > 0 {
+		ctx2, cancel := context.WithTimeout(ctx, timeout*time.Second)
+		ctx = ctx2
+		defer cancel()
+	}
+
+	cl, err := client.New(ctx, c.GlobalString("addr"), opts...)
+	if err != nil {
+		return nil, err
+	}
+
+	wait := c.GlobalBool("wait")
+	if wait {
+		if err := cl.Wait(ctx); err != nil {
+			return nil, err
+		}
+	}
 
-	return client.New(ctx, c.GlobalString("addr"), opts...)
+	return cl, nil
 }
 
 func ParseTemplate(format string) (*template.Template, error) {

cmd/buildctl/main.go

@@ -87,6 +87,10 @@ func main() {
 			Usage: "timeout backend connection after value seconds",
 			Value: 5,
 		},
+		cli.BoolFlag{
+			Name:  "wait",
+			Usage: "block RPCs until the connection becomes available",
+		},
 	}
 
 	app.Commands = []cli.Command{

docs/reference/buildctl.md

@@ -30,6 +30,7 @@ GLOBAL OPTIONS:
    --tlskey value         client key
    --tlsdir value         directory containing CA certificate, client certificate, and client key
    --timeout value        timeout backend connection after value seconds (default: 5)
+   --wait                 block RPCs until the connection becomes available
    --help, -h             show help
    --version, -v          print the version
 ```