driver: add feature testing

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

build/build.go

@@ -50,7 +50,8 @@ func Build(ctx context.Context, drivers []driver.Driver, opt map[string]Options,
 	}
 
 	pwOld := pw
-	c, pw, err := driver.Boot(ctx, drivers[0], pw)
+	d := drivers[0]
+	c, pw, err := driver.Boot(ctx, d, pw)
 	if err != nil {
 		close(pwOld.Status())
 		<-pwOld.Done()
@@ -94,6 +95,28 @@ func Build(ctx context.Context, drivers []driver.Driver, opt map[string]Options,
 				}
 			}
 		}
+
+		for i, e := range opt.Exports {
+			if e.Type == "oci" && !d.Features()[driver.OCIExporter] {
+				return nil, notSupported(d, driver.OCIExporter)
+			}
+			if e.Type == "docker" && e.Output != nil && !d.Features()[driver.DockerExporter] {
+				return nil, notSupported(d, driver.DockerExporter)
+			}
+			if e.Type == "image" {
+				if _, ok := d.(interface {
+					IsDefaultMobyDriver()
+				}); ok {
+					opt.Exports[i].Type = "moby"
+					if e.Attrs["push"] != "" {
+						if ok, _ := strconv.ParseBool(e.Attrs["push"]); ok {
+							return nil, errors.Errorf("auto-push is currently not implemented for moby driver")
+						}
+					}
+				}
+			}
+		}
+
 		// TODO: handle loading to docker daemon
 
 		so.Exports = opt.Exports
@@ -124,6 +147,9 @@ func Build(ctx context.Context, drivers []driver.Driver, opt map[string]Options,
 			for i, p := range opt.Platforms {
 				pp[i] = platforms.Format(p)
 			}
+			if len(pp) > 1 && !d.Features()[driver.MultiPlatform] {
+				return nil, notSupported(d, driver.MultiPlatform)
+			}
 			so.FrontendAttrs["platform"] = strings.Join(pp, ",")
 		}
 
@@ -180,3 +206,7 @@ func LoadInputs(inp Inputs, target *client.SolveOpt) error {
 	target.FrontendAttrs["filename"] = filepath.Base(inp.DockerfilePath)
 	return nil
 }
+
+func notSupported(d driver.Driver, f driver.Feature) error {
+	return errors.Errorf("%s feature is currently not supported for %s driver. Please switch to a different driver (eg. \"docker buildx new\")", f, d.Factory().Name())
+}

driver/docker-container/driver.go

@@ -24,6 +24,7 @@ var buildkitImage = "moby/buildkit:master" // TODO: make this verified and confi
 
 type Driver struct {
 	driver.InitConfig
+	factory driver.Factory
 	version dockertypes.Version
 }
 
@@ -190,6 +191,20 @@ func (d *Driver) Client(ctx context.Context) (*client.Client, error) {
 	}))
 }
 
+func (d *Driver) Factory() driver.Factory {
+	return d.factory
+}
+
+func (d *Driver) Features() map[driver.Feature]bool {
+	return map[driver.Feature]bool{
+		driver.OCIExporter:    true,
+		driver.DockerExporter: true,
+
+		driver.CacheExport:   true,
+		driver.MultiPlatform: true,
+	}
+}
+
 func demuxConn(c net.Conn) net.Conn {
 	pr, pw := io.Pipe()
 	// TODO: rewrite parser with Reader() to avoid goroutine switch

driver/docker-container/factory.go

@@ -42,5 +42,5 @@ func (f *factory) New(ctx context.Context, cfg driver.InitConfig) (driver.Driver
 		return nil, errors.Wrapf(driver.ErrNotConnecting, err.Error())
 	}
 
-	return &Driver{InitConfig: cfg, version: v}, nil
+	return &Driver{factory: f, InitConfig: cfg, version: v}, nil
 }

driver/docker/driver.go

@@ -12,9 +12,8 @@ import (
 	"github.com/tonistiigi/buildx/util/progress"
 )
 
-var buildkitImage = "moby/buildkit:master" // TODO: make this verified and configuratble
-
 type Driver struct {
+	factory driver.Factory
 	driver.InitConfig
 	version dockertypes.Version
 }
@@ -46,3 +45,19 @@ func (d *Driver) Client(ctx context.Context) (*client.Client, error) {
 		return d.DockerAPI.DialHijack(ctx, "/grpc", "h2c", nil)
 	}))
 }
+
+func (d *Driver) Features() map[driver.Feature]bool {
+	return map[driver.Feature]bool{
+		driver.OCIExporter:    false,
+		driver.DockerExporter: false,
+
+		driver.CacheExport:   false,
+		driver.MultiPlatform: false,
+	}
+}
+
+func (d *Driver) Factory() driver.Factory {
+	return d.factory
+}
+
+func (d *Driver) IsDefaultMobyDriver() {}

driver/docker/factory.go

@@ -39,7 +39,7 @@ func (*factory) Priority(cfg driver.InitConfig) int {
 	return prioritySupported
 }
 
-func (*factory) New(ctx context.Context, cfg driver.InitConfig) (driver.Driver, error) {
+func (f *factory) New(ctx context.Context, cfg driver.InitConfig) (driver.Driver, error) {
 	if cfg.DockerAPI == nil {
 		return nil, errors.Errorf("docker driver requires docker API access")
 	}
@@ -49,5 +49,5 @@ func (*factory) New(ctx context.Context, cfg driver.InitConfig) (driver.Driver,
 		return nil, errors.Wrapf(driver.ErrNotConnecting, err.Error())
 	}
 
-	return &Driver{InitConfig: cfg, version: v}, nil
+	return &Driver{factory: f, InitConfig: cfg, version: v}, nil
 }

driver/driver.go

@@ -27,11 +27,13 @@ type Info struct {
 }
 
 type Driver interface {
+	Factory() Factory
 	Bootstrap(context.Context, progress.Logger) error
 	Info(context.Context) (*Info, error)
 	Stop(ctx context.Context, force bool) error
 	Rm(ctx context.Context, force bool) error
 	Client(ctx context.Context) (*client.Client, error)
+	Features() map[Feature]bool
 }
 
 func Boot(ctx context.Context, d Driver, pw progress.Writer) (*client.Client, progress.Writer, error) {

driver/features.go

@@ -0,0 +1,9 @@
+package driver
+
+type Feature string
+
+const OCIExporter Feature = "OCI exporter"
+const DockerExporter Feature = "Docker exporter"
+
+const CacheExport Feature = "cache export"
+const MultiPlatform Feature = "multiple platforms"