bake: support inline dockerfile

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

bake/bake.go

@@ -375,6 +375,7 @@ type Target struct {
 
 	Context          *string           `json:"context,omitempty" hcl:"context,optional"`
 	Dockerfile       *string           `json:"dockerfile,omitempty" hcl:"dockerfile,optional"`
+	DockerfileInline *string           `json:"dockerfile-inline,omitempty" hcl:"dockerfile-inline,optional"`
 	Args             map[string]string `json:"args,omitempty" hcl:"args,optional"`
 	Labels           map[string]string `json:"labels,omitempty" hcl:"labels,optional"`
 	Tags             []string          `json:"tags,omitempty" hcl:"tags,optional"`
@@ -460,6 +461,9 @@ func toBuildOpt(t *Target, inp *Input) (*build.Options, error) {
 		ContextPath:    contextPath,
 		DockerfilePath: dockerfilePath,
 	}
+	if t.DockerfileInline != nil {
+		bi.DockerfileInline = *t.DockerfileInline
+	}
 	updateContext(&bi, inp)
 
 	bo := &build.Options{
@@ -527,6 +531,9 @@ func merge(t1, t2 *Target) *Target {
 	if t2.Dockerfile != nil {
 		t1.Dockerfile = t2.Dockerfile
 	}
+	if t2.DockerfileInline != nil {
+		t1.DockerfileInline = t2.DockerfileInline
+	}
 	for k, v := range t2.Args {
 		if t1.Args == nil {
 			t1.Args = map[string]string{}

build/build.go

@@ -66,6 +66,7 @@ type Inputs struct {
 	DockerfilePath   string
 	InStream         io.Reader
 	ContextState     *llb.State
+	DockerfileInline string
 }
 
 type DriverInfo struct {
@@ -780,6 +781,10 @@ func LoadInputs(ctx context.Context, d driver.Driver, inp Inputs, pw progress.Wr
 		return nil, errors.Errorf("unable to prepare context: path %q not found", inp.ContextPath)
 	}
 
+	if inp.DockerfileInline != "" {
+		dockerfileReader = strings.NewReader(inp.DockerfileInline)
+	}
+
 	if dockerfileReader != nil {
 		dockerfileDir, err = createTempDockerfile(dockerfileReader)
 		if err != nil {