Fix image args that are uppercase

If a Dockerfile contained a build arg that was uppercase for referencing
an image, building would result in an error:

```
failed to parse stage name "localhost:42545/FIRST_IMAGE": invalid reference format: repository name must be lowercase
```

This commit allows users to specify args as all uppercase and lowercases
the name behind the scenes. Uppercase args are common in wild
Dockerfiles

Signed-off-by: Taylor Silva <[email protected]>

Author: taylorsilva

Diff for: registry.go

@@ -5,14 +5,19 @@ import (
 	"io"
 	"net"
 	"net/http"
+	"strings"
 
 	v1 "github.com/google/go-containerregistry/pkg/v1"
 	"github.com/google/go-containerregistry/pkg/v1/tarball"
 	"github.com/julienschmidt/httprouter"
 	"github.com/sirupsen/logrus"
 )
 
-type LocalRegistry map[string]v1.Image
+type ImageArg struct {
+	Image   v1.Image
+	ArgName string
+}
+type LocalRegistry map[string]ImageArg
 
 func LoadRegistry(imagePaths map[string]string) (LocalRegistry, error) {
 	images := LocalRegistry{}
@@ -22,7 +27,7 @@ func LoadRegistry(imagePaths map[string]string) (LocalRegistry, error) {
 			return nil, fmt.Errorf("image from path: %w", err)
 		}
 
-		images[name] = image
+		images[strings.ToLower(name)] = ImageArg{Image: image, ArgName: name}
 	}
 
 	return images, nil
@@ -57,8 +62,8 @@ func ServeRegistry(reg LocalRegistry) (string, error) {
 
 func (registry LocalRegistry) BuildArgs(port string) []string {
 	var buildArgs []string
-	for name := range registry {
-		buildArgs = append(buildArgs, fmt.Sprintf("%s=localhost:%s/%s", name, port, name))
+	for name, image := range registry {
+		buildArgs = append(buildArgs, fmt.Sprintf("%s=localhost:%s/%s", image.ArgName, port, name))
 	}
 
 	return buildArgs
@@ -72,11 +77,12 @@ func (registry LocalRegistry) GetManifest(w http.ResponseWriter, r *http.Request
 		"accept": r.Header["Accept"],
 	}).Debugf("get manifest for %s at %s", name, ref)
 
-	image, found := registry[name]
+	img, found := registry[name]
 	if !found {
 		w.WriteHeader(http.StatusNotFound)
 		return
 	}
+	image := img.Image
 
 	mt, err := image.MediaType()
 	if err != nil {
@@ -122,11 +128,12 @@ func (registry LocalRegistry) GetBlob(w http.ResponseWriter, r *http.Request, p
 		"accept": r.Header["Accept"],
 	}).Debugf("get blob %s", dig)
 
-	image, found := registry[name]
+	img, found := registry[name]
 	if !found {
 		w.WriteHeader(http.StatusNotFound)
 		return
 	}
+	image := img.Image
 
 	hash, err := v1.NewHash(dig)
 	if err != nil {

Diff for: task_test.go

@@ -373,6 +373,43 @@ func (s *TaskSuite) TestImageArgs() {
 	}
 }
 
+func (s *TaskSuite) TestImageArgsWithUppercaseName() {
+	imagesDir, err := ioutil.TempDir("", "preload-images")
+	s.NoError(err)
+
+	defer os.RemoveAll(imagesDir)
+
+	image, err := random.Image(1024, 2)
+	s.NoError(err)
+	imagePath := filepath.Join(imagesDir, "first.tar")
+	err = tarball.WriteToFile(imagePath, nil, image)
+	s.NoError(err)
+
+	s.req.Config.ContextDir = "testdata/image-args"
+	s.req.Config.DockerfilePath = "testdata/image-args/Dockerfile.uppercase"
+	s.req.Config.ImageArgs = []string{
+		"FIRST_IMAGE=" + imagePath,
+	}
+	s.req.Config.UnpackRootfs = true
+
+	_, err = s.build()
+	s.NoError(err)
+
+	meta, err := s.imageMetadata("image")
+	s.NoError(err)
+
+	rootfsContent, err := ioutil.ReadFile(s.imagePath("rootfs", "Dockerfile.second"))
+	s.NoError(err)
+
+	expectedContent, err := ioutil.ReadFile("testdata/image-args/Dockerfile.uppercase")
+	s.NoError(err)
+
+	s.Equal(rootfsContent, expectedContent)
+
+	s.Equal(meta.User, "banana")
+	s.Equal(meta.Env, []string{"PATH=/darkness", "BA=nana"})
+}
+
 func (s *TaskSuite) TestImageArgsUnpack() {
 	imagesDir, err := ioutil.TempDir("", "preload-images")
 	s.NoError(err)

Diff for: testdata/image-args/Dockerfile.uppercase

@@ -0,0 +1,7 @@
+ARG FIRST_IMAGE
+
+FROM ${FIRST_IMAGE}
+USER banana
+ENV PATH=/darkness
+ENV BA=nana
+COPY Dockerfile.uppercase /Dockerfile.second