Fix building from http or '-' options

When copying from a URL, podman will download and create a context
directory in a temporary file.  The problem was that this directory
was being removed as soon as the function that created it was returned.

Later the build code would look for content in the temporary directory
and fail to find it, blowing up the build.

By pulling the extraction code back into the build function, we keep the
temporary directory around until the build completes.

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

cmd/podman/images/build.go

@@ -138,36 +138,9 @@ func build(cmd *cobra.Command, args []string) error {
 		return errors.New("cannot specify --squash, --squash-all and --layers options together")
 	}
 
-	contextDir, containerFiles, err := extractContextAndFiles(args, buildOpts.File)
-	if err != nil {
-		return err
-	}
-
-	ie, err := registry.NewImageEngine(cmd, args)
-	if err != nil {
-		return err
-	}
-
-	apiBuildOpts, err := buildFlagsWrapperToOptions(cmd, contextDir, &buildOpts)
-	if err != nil {
-		return err
-	}
-
-	_, err = ie.Build(registry.GetContext(), containerFiles, *apiBuildOpts)
-	return err
-}
-
-// extractContextAndFiles parses args and files to extract a context directory
-// and {Container,Docker}files.
-//
-// TODO: this was copied and altered from the v1 client which in turn was
-// copied and altered from the Buildah code. Ideally, all of this code should
-// be cleanly consolidated into a package that is shared between Buildah and
-// Podman.
-func extractContextAndFiles(args, files []string) (string, []string, error) {
 	// Extract container files from the CLI (i.e., --file/-f) first.
 	var containerFiles []string
-	for _, f := range files {
+	for _, f := range buildOpts.File {
 		if f == "-" {
 			containerFiles = append(containerFiles, "/dev/stdin")
 		} else {
@@ -181,7 +154,7 @@ func extractContextAndFiles(args, files []string) (string, []string, error) {
 		// The context directory could be a URL.  Try to handle that.
 		tempDir, subDir, err := imagebuildah.TempDirForURL("", "buildah", args[0])
 		if err != nil {
-			return "", nil, errors.Wrapf(err, "error prepping temporary context directory")
+			return errors.Wrapf(err, "error prepping temporary context directory")
 		}
 		if tempDir != "" {
 			// We had to download it to a temporary directory.
@@ -196,7 +169,7 @@ func extractContextAndFiles(args, files []string) (string, []string, error) {
 			// Nope, it was local.  Use it as is.
 			absDir, err := filepath.Abs(args[0])
 			if err != nil {
-				return "", nil, errors.Wrapf(err, "error determining path to directory %q", args[0])
+				return errors.Wrapf(err, "error determining path to directory %q", args[0])
 			}
 			contextDir = absDir
 		}
@@ -212,7 +185,7 @@ func extractContextAndFiles(args, files []string) (string, []string, error) {
 			}
 			absFile, err := filepath.Abs(containerFiles[i])
 			if err != nil {
-				return "", nil, errors.Wrapf(err, "error determining path to file %q", containerFiles[i])
+				return errors.Wrapf(err, "error determining path to file %q", containerFiles[i])
 			}
 			contextDir = filepath.Dir(absFile)
 			break
@@ -220,10 +193,10 @@ func extractContextAndFiles(args, files []string) (string, []string, error) {
 	}
 
 	if contextDir == "" {
-		return "", nil, errors.Errorf("no context directory and no Containerfile specified")
+		return errors.Errorf("no context directory and no Containerfile specified")
 	}
 	if !utils.IsDir(contextDir) {
-		return "", nil, errors.Errorf("context must be a directory: %q", contextDir)
+		return errors.Errorf("context must be a directory: %q", contextDir)
 	}
 	if len(containerFiles) == 0 {
 		if utils.FileExists(filepath.Join(contextDir, "Containerfile")) {
@@ -233,7 +206,18 @@ func extractContextAndFiles(args, files []string) (string, []string, error) {
 		}
 	}
 
-	return contextDir, containerFiles, nil
+	ie, err := registry.NewImageEngine(cmd, args)
+	if err != nil {
+		return err
+	}
+
+	apiBuildOpts, err := buildFlagsWrapperToOptions(cmd, contextDir, &buildOpts)
+	if err != nil {
+		return err
+	}
+
+	_, err = ie.Build(registry.GetContext(), containerFiles, *apiBuildOpts)
+	return err
 }
 
 // buildFlagsWrapperToOptions converts the local build flags to the build options used

test/system/070-build.bats

@@ -177,6 +177,27 @@ Labels.$label_name | $label_value
     run_podman rmi -f build_test
 }
 
+@test "podman build - stdin test" {
+    if is_remote && is_rootless; then
+        skip "unreliable with podman-remote and rootless; #2972"
+    fi
+
+    # Random workdir, and multiple random strings to verify command & env
+    workdir=/$(random_string 10)
+    PODMAN_TIMEOUT=240 run_podman build -t build_test - << EOF
+FROM  $IMAGE
+RUN mkdir $workdir
+WORKDIR $workdir
+RUN /bin/echo 'Test'
+EOF
+    is "$output" ".*STEP 5: COMMIT" "COMMIT seen in log"
+
+    run_podman run --rm build_test pwd
+    is "$output" "$workdir" "pwd command in container"
+
+    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