rootfs: Add support for rootfs-overlay and bump to buildah v1.22.1-0.202108

Allows users to specify a readonly rootfs with :O, in exchange podman will create a writable overlay.

bump builah to v1.22.1-0.20210823173221-da2b428c56ce

[NO TESTS NEEDED]

Signed-off-by: flouthoc <flouthoc.git@gmail.com>

2 files changed, 11 insertions, 2 deletions

diff --git a/pkg/specgen/generate/container_create.go b/pkg/specgen/generate/container_create.go
index f82b2a3c6..fbb229e1c 100644
--- a/pkg/specgen/generate/container_create.go
+++ b/pkg/specgen/generate/container_create.go
@@ -90,7 +90,7 @@ func MakeContainer(ctx context.Context, rt *libpod.Runtime, s *specgen.SpecGener
 	var newImage *libimage.Image
 	var imageData *libimage.ImageData
 	if s.Rootfs != "" {
-		options = append(options, libpod.WithRootFS(s.Rootfs))
+		options = append(options, libpod.WithRootFS(s.Rootfs, s.RootfsOverlay))
 	} else {
 		var resolvedImageName string
 		newImage, resolvedImageName, err = rt.LibimageRuntime().LookupImage(s.Image, nil)
@@ -394,7 +394,7 @@ func createContainerOptions(ctx context.Context, rt *libpod.Runtime, s *specgen.
 		options = append(options, libpod.WithShmSize(*s.ShmSize))
 	}
 	if s.Rootfs != "" {
-		options = append(options, libpod.WithRootFS(s.Rootfs))
+		options = append(options, libpod.WithRootFS(s.Rootfs, s.RootfsOverlay))
 	}
 	// Default used if not overridden on command line
 
diff --git a/pkg/specgen/specgen.go b/pkg/specgen/specgen.go
index 0c30c498a..e0609c5bc 100644
--- a/pkg/specgen/specgen.go
+++ b/pkg/specgen/specgen.go
@@ -2,6 +2,7 @@ package specgen
 
 import (
 	"net"
+	"strings"
 	"syscall"
 
 	"github.com/containers/image/v5/manifest"
@@ -209,6 +210,8 @@ type ContainerStorageConfig struct {
 	// Conflicts with Image.
 	// At least one of Image or Rootfs must be specified.
 	Rootfs string `json:"rootfs,omitempty"`
+	// RootfsOverlay tells if rootfs is actuall an overlay on top of base path
+	RootfsOverlay bool `json:"rootfs_overlay,omitempty"`
 	// ImageVolumeMode indicates how image volumes will be created.
 	// Supported modes are "ignore" (do not create), "tmpfs" (create as
 	// tmpfs), and "anonymous" (create as anonymous volumes).
@@ -528,6 +531,12 @@ func NewSpecGenerator(arg string, rootfs bool) *SpecGenerator {
 	csc := ContainerStorageConfig{}
 	if rootfs {
 		csc.Rootfs = arg
+		// check if rootfs is actually overlayed
+		parts := strings.SplitN(csc.Rootfs, ":", 2)
+		if len(parts) > 1 && parts[1] == "O" {
+			csc.RootfsOverlay = true
+			csc.Rootfs = parts[0]
+		}
 	} else {
 		csc.Image = arg
 	}