Make ClientOpts type safe

This provides some compile-time safety around options passed when
creating a buildkit client.
Before this change since a ClientOpt is an empty interface anything and
everything could be passed in.

This is a breaking change since before consumers could pass in a raw
grpc.DialOption, this now needs to be wrapped with
`client.WithGRPCDialOption(grpcOpt)`
Consumers could also pass in something tat was not a client opt at all
and it was completely ignored.

Signed-off-by: Brian Goff <[email protected]>

Author: cpuguy83

client/client.go

@@ -34,7 +34,9 @@ type Client struct {
 	sessionDialer func(ctx context.Context, proto string, meta map[string][]string) (net.Conn, error)
 }
 
-type ClientOpt interface{}
+type ClientOpt interface {
+	isClientOpt()
+}
 
 // New returns a new buildkit client. Address can be empty for the system-default address.
 func New(ctx context.Context, address string, opts ...ClientOpt) (*Client, error) {
@@ -82,8 +84,8 @@ func New(ctx context.Context, address string, opts ...ClientOpt) (*Client, error
 		if sd, ok := o.(*withSessionDialer); ok {
 			sessionDialer = sd.dialer
 		}
-		if opt, ok := o.(grpc.DialOption); ok {
-			customDialOptions = append(customDialOptions, opt)
+		if opt, ok := o.(*withGRPCDialOption); ok {
+			customDialOptions = append(customDialOptions, opt.opt)
 		}
 	}
 
@@ -182,6 +184,8 @@ func (c *Client) Close() error {
 
 type withFailFast struct{}
 
+func (*withFailFast) isClientOpt() {}
+
 func WithFailFast() ClientOpt {
 	return &withFailFast{}
 }
@@ -190,6 +194,8 @@ type withDialer struct {
 	dialer func(context.Context, string) (net.Conn, error)
 }
 
+func (*withDialer) isClientOpt() {}
+
 func WithContextDialer(df func(context.Context, string) (net.Conn, error)) ClientOpt {
 	return &withDialer{dialer: df}
 }
@@ -201,6 +207,8 @@ type withCredentials struct {
 	Key        string
 }
 
+func (*withCredentials) isClientOpt() {}
+
 // WithCredentials configures the TLS parameters of the client.
 // Arguments:
 // * serverName: specifies the name of the target server
@@ -247,6 +255,8 @@ type withTracer struct {
 	tp trace.TracerProvider
 }
 
+func (w *withTracer) isClientOpt() {}
+
 type TracerDelegate interface {
 	SetSpanExporter(context.Context, sdktrace.SpanExporter) error
 }
@@ -261,6 +271,8 @@ type withTracerDelegate struct {
 	TracerDelegate
 }
 
+func (w *withTracerDelegate) isClientOpt() {}
+
 func WithSessionDialer(dialer func(context.Context, string, map[string][]string) (net.Conn, error)) ClientOpt {
 	return &withSessionDialer{dialer}
 }
@@ -269,6 +281,8 @@ type withSessionDialer struct {
 	dialer func(context.Context, string, map[string][]string) (net.Conn, error)
 }
 
+func (w *withSessionDialer) isClientOpt() {}
+
 func resolveDialer(address string) (func(context.Context, string) (net.Conn, error), error) {
 	ch, err := connhelper.GetConnectionHelper(address)
 	if err != nil {
@@ -289,3 +303,13 @@ func filterInterceptor(intercept grpc.UnaryClientInterceptor) grpc.UnaryClientIn
 		return intercept(ctx, method, req, reply, cc, invoker, opts...)
 	}
 }
+
+type withGRPCDialOption struct {
+	opt grpc.DialOption
+}
+
+func (*withGRPCDialOption) isClientOpt() {}
+
+func WithGRPCDialOption(opt grpc.DialOption) ClientOpt {
+	return &withGRPCDialOption{opt}
+}

client/client_test.go

@@ -9036,7 +9036,7 @@ func testClientCustomGRPCOpts(t *testing.T, sb integration.Sandbox) {
 		interceptedMethods = append(interceptedMethods, method)
 		return invoker(ctx, method, req, reply, cc, opts...)
 	}
-	c, err := New(sb.Context(), sb.Address(), grpc.WithChainUnaryInterceptor(intercept))
+	c, err := New(sb.Context(), sb.Address(), WithGRPCDialOption(grpc.WithChainUnaryInterceptor(intercept)))
 	require.NoError(t, err)
 	defer c.Close()