command(bake): Specify local and remote bake files

This adds the ability to source additional local build definition files when
sourcing Bake files via a remote url.
Prefixing a file with 'cwd://' will source a bake file on the local
machine, instead of the remote location.
Local files will be read/have precedence before remote files.

Usage:
```
docker buildx bake https://github.com/example/upstream.git --file cwd://docker-bake.override.hcl --print
```
This will source a default file from the example/upstream repository,
and also source a build definition from the local machine.

Also moves remote and local files reading logic to a func

Signed-off-by: CrazyMax <[email protected]>
Signed-off-by: Cameron Adams <[email protected]>
Co-authored-by: CrazyMax <[email protected]>

commands/bake.go

@@ -4,7 +4,9 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"os"
+	"strings"
 
 	"github.com/containerd/console"
 	"github.com/containerd/containerd/platforms"
@@ -98,8 +100,6 @@ func runBake(dockerCli command.Cli, targets []string, in bakeOptions, cFlags com
 	defer cancel()
 
 	var nodes []builder.Node
-	var files []bake.File
-	var inp *bake.Input
 	var progressConsoleDesc, progressTextDesc string
 
 	// instance only needed for reading remote bake files or building
@@ -147,14 +147,7 @@ func runBake(dockerCli command.Cli, targets []string, in bakeOptions, cFlags com
 		}
 	}()
 
-	if url != "" {
-		files, inp, err = bake.ReadRemoteFiles(ctx, nodes, url, in.files, printer)
-	} else {
-		progress.Wrap("[internal] load local bake definitions", printer.Write, func(sub progress.SubLogger) error {
-			files, err = bake.ReadLocalFiles(in.files, dockerCli.In(), sub)
-			return nil
-		})
-	}
+	files, inp, err := readBakeFiles(ctx, nodes, url, in.files, dockerCli.In(), printer)
 	if err != nil {
 		return err
 	}
@@ -296,3 +289,40 @@ func saveLocalStateGroup(dockerCli command.Cli, ref string, lsg localstate.State
 	}
 	return l.SaveGroup(ref, lsg)
 }
+
+func readBakeFiles(ctx context.Context, nodes []builder.Node, url string, names []string, stdin io.Reader, pw progress.Writer) (files []bake.File, inp *bake.Input, err error) {
+	var lnames []string
+	var rnames []string
+	for _, v := range names {
+		if strings.HasPrefix(v, "cwd://") {
+			lnames = append(lnames, strings.TrimPrefix(v, "cwd://"))
+		} else {
+			rnames = append(rnames, v)
+		}
+	}
+
+	if len(lnames) > 0 || url == "" {
+		progress.Wrap("[internal] load local bake definitions", pw.Write, func(sub progress.SubLogger) error {
+			if url != "" {
+				files, err = bake.ReadLocalFiles(lnames, stdin, sub)
+			} else {
+				files, err = bake.ReadLocalFiles(append(lnames, rnames...), stdin, sub)
+			}
+			return nil
+		})
+		if err != nil {
+			return nil, nil, err
+		}
+	}
+
+	if url != "" {
+		var rfiles []bake.File
+		rfiles, inp, err = bake.ReadRemoteFiles(ctx, nodes, url, rnames, pw)
+		if err != nil {
+			return nil, nil, err
+		}
+		files = append(files, rfiles...)
+	}
+
+	return
+}

tests/bake.go

@@ -23,6 +23,7 @@ var bakeTests = []func(t *testing.T, sb integration.Sandbox){
 	testBakeLocalMulti,
 	testBakeRemote,
 	testBakeRemoteCmdContext,
+	testBakeRemoteLocalOverride,
 	testBakeRemoteCmdContextOverride,
 	testBakeRemoteContextSubdir,
 	testBakeRemoteCmdContextEscapeRoot,
@@ -89,6 +90,11 @@ services:
 	require.Contains(t, string(out), `#1 reading docker-bake.hcl`)
 
 	require.FileExists(t, filepath.Join(dirDest, "foo"))
+
+	out, err = bakeCmd(sb, withDir(dir), withArgs("--file", "cwd://docker-bake.hcl", "--set", "*.output=type=local,dest="+dirDest))
+	require.NoError(t, err, out)
+
+	require.FileExists(t, filepath.Join(dirDest, "foo"))
 }
 
 func testBakeRemote(t *testing.T, sb integration.Sandbox) {
@@ -121,6 +127,48 @@ EOT
 	require.FileExists(t, filepath.Join(dirDest, "foo"))
 }
 
+func testBakeRemoteLocalOverride(t *testing.T, sb integration.Sandbox) {
+	remoteBakefile := []byte(`
+target "default" {
+	dockerfile-inline = <<EOT
+FROM scratch
+COPY foo /foo
+EOT
+}
+`)
+	localBakefile := []byte(`
+target "default" {
+	dockerfile-inline = <<EOT
+FROM scratch
+COPY bar /bar
+EOT
+}
+`)
+	dirSpec := tmpdir(
+		t,
+		fstest.CreateFile("docker-bake.hcl", remoteBakefile, 0600),
+		fstest.CreateFile("bar", []byte("bar"), 0600),
+	)
+	dirSrc := tmpdir(
+		t,
+		fstest.CreateFile("local-docker-bake.hcl", localBakefile, 0600),
+	)
+	dirDest := t.TempDir()
+
+	git, err := gitutil.New(gitutil.WithWorkingDir(dirSpec))
+	require.NoError(t, err)
+
+	gitutil.GitInit(git, t)
+	gitutil.GitAdd(git, t, "docker-bake.hcl", "bar")
+	gitutil.GitCommit(git, t, "initial commit")
+	addr := gitutil.GitServeHTTP(git, t)
+
+	out, err := bakeCmd(sb, withDir(dirSrc), withArgs(addr, "--file", "cwd://local-docker-bake.hcl", "--set", "*.output=type=local,dest="+dirDest))
+	require.NoError(t, err, out)
+
+	require.FileExists(t, filepath.Join(dirDest, "bar"))
+}
+
 func testBakeRemoteCmdContext(t *testing.T, sb integration.Sandbox) {
 	bakefile := []byte(`
 target "default" {