build: allow dockerfile from URL

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

build/build.go

@@ -285,7 +285,7 @@ func isDefaultMobyDriver(d driver.Driver) bool {
 	return ok
 }
 
-func toSolveOpt(d driver.Driver, multiDriver bool, opt Options, dl dockerLoadCallback) (solveOpt *client.SolveOpt, release func(), err error) {
+func toSolveOpt(ctx context.Context, d driver.Driver, multiDriver bool, opt Options, pw progress.Writer, dl dockerLoadCallback) (solveOpt *client.SolveOpt, release func(), err error) {
 	defers := make([]func(), 0, 2)
 	releaseF := func() {
 		for _, f := range defers {
@@ -425,7 +425,7 @@ func toSolveOpt(d driver.Driver, multiDriver bool, opt Options, dl dockerLoadCal
 	so.Exports = opt.Exports
 	so.Session = opt.Session
 
-	releaseLoad, err := LoadInputs(opt.Inputs, &so)
+	releaseLoad, err := LoadInputs(ctx, d, opt.Inputs, pw, &so)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -530,7 +530,7 @@ func Build(ctx context.Context, drivers []DriverInfo, opt map[string]Options, do
 		for i, dp := range m[k] {
 			d := drivers[dp.driverIndex].Driver
 			opt.Platforms = dp.platforms
-			so, release, err := toSolveOpt(d, multiDriver, opt, func(name string) (io.WriteCloser, func(), error) {
+			so, release, err := toSolveOpt(ctx, d, multiDriver, opt, pw, func(name string) (io.WriteCloser, func(), error) {
 				return newDockerLoader(ctx, docker, name, mw)
 			})
 			if err != nil {
@@ -720,7 +720,7 @@ func createTempDockerfile(r io.Reader) (string, error) {
 	return dir, err
 }
 
-func LoadInputs(inp Inputs, target *client.SolveOpt) (func(), error) {
+func LoadInputs(ctx context.Context, d driver.Driver, inp Inputs, pw progress.Writer, target *client.SolveOpt) (func(), error) {
 	if inp.ContextPath == "" {
 		return nil, errors.New("please specify build context (e.g. \".\" for the current directory)")
 	}
@@ -746,7 +746,7 @@ func LoadInputs(inp Inputs, target *client.SolveOpt) (func(), error) {
 		if err != nil && err != io.EOF {
 			return nil, errors.Wrap(err, "failed to peek context header from STDIN")
 		}
-
+		if !(err == io.EOF && len(magic) == 0) {
 			if isArchive(magic) {
 				// stdin is context
 				up := uploadprovider.New()
@@ -762,6 +762,7 @@ func LoadInputs(inp Inputs, target *client.SolveOpt) (func(), error) {
 				toRemove = append(toRemove, inp.ContextPath)
 				target.LocalDirs["context"] = inp.ContextPath
 			}
+		}
 
 	case isLocalDir(inp.ContextPath):
 		target.LocalDirs["context"] = inp.ContextPath
@@ -791,6 +792,16 @@ func LoadInputs(inp Inputs, target *client.SolveOpt) (func(), error) {
 		}
 		toRemove = append(toRemove, dockerfileDir)
 		dockerfileName = "Dockerfile"
+		target.FrontendAttrs["dockerfilekey"] = "dockerfile"
+	}
+	if urlutil.IsURL(inp.DockerfilePath) {
+		dockerfileDir, err = createTempDockerfileFromURL(ctx, d, inp.DockerfilePath, pw)
+		if err != nil {
+			return nil, err
+		}
+		toRemove = append(toRemove, dockerfileDir)
+		dockerfileName = "Dockerfile"
+		target.FrontendAttrs["dockerfilekey"] = "dockerfile"
 	}
 
 	if dockerfileName == "" {

build/url.go

@@ -0,0 +1,69 @@
+package build
+
+import (
+	"context"
+	"io/ioutil"
+	"path/filepath"
+
+	"github.com/docker/buildx/driver"
+	"github.com/docker/buildx/util/progress"
+	"github.com/moby/buildkit/client"
+	"github.com/moby/buildkit/client/llb"
+	gwclient "github.com/moby/buildkit/frontend/gateway/client"
+	"github.com/pkg/errors"
+)
+
+func createTempDockerfileFromURL(ctx context.Context, d driver.Driver, url string, pw progress.Writer) (string, error) {
+	c, err := d.Client(ctx)
+	if err != nil {
+		return "", err
+	}
+	var out string
+	_, err = c.Build(ctx, client.SolveOpt{}, "buildx", func(ctx context.Context, c gwclient.Client) (*gwclient.Result, error) {
+		def, err := llb.HTTP(url, llb.Filename("Dockerfile"), llb.WithCustomNamef("[internal] load %s", url)).Marshal(ctx)
+		if err != nil {
+			return nil, err
+		}
+
+		res, err := c.Solve(ctx, gwclient.SolveRequest{
+			Definition: def.ToPB(),
+		})
+		if err != nil {
+			return nil, err
+		}
+		ref, err := res.SingleRef()
+		if err != nil {
+			return nil, err
+		}
+		stat, err := ref.StatFile(ctx, gwclient.StatRequest{
+			Path: "Dockerfile",
+		})
+		if err != nil {
+			return nil, err
+		}
+		if stat.Size() > 512*1024 {
+			return nil, errors.Errorf("Dockerfile %s bigger than allowed max size", url)
+		}
+
+		dt, err := ref.ReadFile(ctx, gwclient.ReadRequest{
+			Filename: "Dockerfile",
+		})
+		if err != nil {
+			return nil, err
+		}
+		dir, err := ioutil.TempDir("", "buildx")
+		if err != nil {
+			return nil, err
+		}
+		if err := ioutil.WriteFile(filepath.Join(dir, "Dockerfile"), dt, 0600); err != nil {
+			return nil, err
+		}
+		out = dir
+		return nil, nil
+	}, pw.Status())
+
+	if err != nil {
+		return "", err
+	}
+	return out, nil
+}

driver/manager.go

@@ -5,10 +5,12 @@ import (
 	"io/ioutil"
 	"sort"
 	"strings"
+	"sync"
 
 	"k8s.io/client-go/rest"
 
 	dockerclient "github.com/docker/docker/client"
+	"github.com/moby/buildkit/client"
 	"github.com/pkg/errors"
 )
 
@@ -117,9 +119,27 @@ func GetDriver(ctx context.Context, name string, f Factory, api dockerclient.API
 			return nil, err
 		}
 	}
-	return f.New(ctx, ic)
+	d, err := f.New(ctx, ic)
+	if err != nil {
+		return nil, err
+	}
+	return &cachedDriver{Driver: d}, nil
 }
 
 func GetFactories() map[string]Factory {
 	return drivers
 }
+
+type cachedDriver struct {
+	Driver
+	client *client.Client
+	err    error
+	once   sync.Once
+}
+
+func (d *cachedDriver) Client(ctx context.Context) (*client.Client, error) {
+	d.once.Do(func() {
+		d.client, d.err = d.Driver.Client(ctx)
+	})
+	return d.client, d.err
+}