podman build --remote URI Dockerfile shoud not be treated as file

Podman build --remote is translating https://path as if it was a file
path. This change will leave it as a URL so it can be parsed on the
server side.

Fixed: https://github.com/containers/podman/issues/20475

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

pkg/api/handlers/compat/images_build.go

@@ -224,8 +224,14 @@ func BuildImage(w http.ResponseWriter, r *http.Request) {
 				// it's not json, assume just a string
 				m = []string{query.Dockerfile}
 			}
+
 			for _, containerfile := range m {
-				containerFiles = append(containerFiles, filepath.Join(contextDirectory, filepath.Clean(filepath.FromSlash(containerfile))))
+				// Add path to containerfile iff it is not URL
+				if !(strings.HasPrefix(containerfile, "http://") || strings.HasPrefix(containerfile, "https://")) {
+					containerfile = filepath.Join(contextDirectory,
+						filepath.Clean(filepath.FromSlash(containerfile)))
+				}
+				containerFiles = append(containerFiles, containerfile)
 			}
 			dockerFileSet = true
 		}

pkg/bindings/images/build.go

@@ -431,6 +431,11 @@ func Build(ctx context.Context, containerFiles []string, options entities.BuildO
 
 	dontexcludes := []string{"!Dockerfile", "!Containerfile", "!.dockerignore", "!.containerignore"}
 	for _, c := range containerFiles {
+		// Don not add path to containerfile if it is a URL
+		if strings.HasPrefix(c, "http://") || strings.HasPrefix(c, "https://") {
+			newContainerFiles = append(newContainerFiles, c)
+			continue
+		}
 		if c == "/dev/stdin" {
 			content, err := io.ReadAll(os.Stdin)
 			if err != nil {

test/system/070-build.bats

@@ -1135,6 +1135,12 @@ EOF
     run_podman rmi -f build_test
 }
 
+@test "podman build --file=https" {
+    run_podman build -t build_test --file=https://raw.githubusercontent.com/containers/podman/main/test/build/from-scratch/Dockerfile $PODMAN_TMPDIR
+
+    run_podman rmi -f build_test
+}
+
 function teardown() {
     # A timeout or other error in 'build' can leave behind stale images
     # that podman can't even see and which will cascade into subsequent