Add quadlet support for rootfs= containers

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

Add rootfs= support for quadlet containers

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

docs/source/markdown/podman-systemd.unit.5.md

@@ -188,6 +188,14 @@ This key can be listed multiple times.
 If enabled (which is the default), this disables the container processes from gaining additional privileges via things like
 setuid and file capabilities.
 
+#### `Rootfs=`
+
+The rootfs to use for the container. Rootfs points to a directory on the system that contains the content to be run within the container. This option conflicts with the `Image` option.
+
+The format of the rootfs is the same as when passed to `podman run --rootfs`, so it supports ovelay mounts as well.
+
+Note: On SELinux systems, the rootfs needs the correct label, which is by default unconfined_u:object_r:container_file_t:s0.
+
 #### `Notify=` (defaults to `no`)
 
 By default, Podman is run in such a way that the systemd startup notify command is handled by

pkg/systemd/quadlet/quadlet.go

@@ -45,6 +45,7 @@ const (
 	KeyRemapUID          = "RemapUid"
 	KeyRemapGID          = "RemapGid"
 	KeyRemapUIDSize      = "RemapUidSize"
+	KeyRootfs            = "Rootfs"
 	KeyNotify            = "Notify"
 	KeyExposeHostPort    = "ExposeHostPort"
 	KeyPublishPort       = "PublishPort"
@@ -96,6 +97,7 @@ var (
 		KeyRemapUID:        true,
 		KeyRemapGID:        true,
 		KeyRemapUIDSize:    true,
+		KeyRootfs:          true,
 		KeyNotify:          true,
 		KeyExposeHostPort:  true,
 		KeyPublishPort:     true,
@@ -239,9 +241,14 @@ func ConvertContainer(container *parser.UnitFile, isUser bool) (*parser.UnitFile
 	// Rename old Container group to x-Container so that systemd ignores it
 	service.RenameGroup(ContainerGroup, XContainerGroup)
 
-	image, ok := container.Lookup(ContainerGroup, KeyImage)
-	if !ok || len(image) == 0 {
-		return nil, fmt.Errorf("no Image key specified")
+	// One image or rootfs must be specified for the container
+	image, _ := container.Lookup(ContainerGroup, KeyImage)
+	rootfs, _ := container.Lookup(ContainerGroup, KeyRootfs)
+	if len(image) == 0 && len(rootfs) == 0 {
+		return nil, fmt.Errorf("no Image or Rootfs key specified")
+	}
+	if len(image) > 0 && len(rootfs) > 0 {
+		return nil, fmt.Errorf("the Image And Rootfs keys conflict can not be specified together")
 	}
 
 	containerName, ok := container.Lookup(ContainerGroup, KeyContainerName)
@@ -486,7 +493,11 @@ func ConvertContainer(container *parser.UnitFile, isUser bool) (*parser.UnitFile
 	podmanArgs := container.LookupAllArgs(ContainerGroup, KeyPodmanArgs)
 	podman.add(podmanArgs...)
 
-	podman.add(image)
+	if len(image) > 0 {
+		podman.add(image)
+	} else {
+		podman.add("--rootfs", rootfs)
+	}
 
 	execArgs, ok := container.LookupLastArgs(ContainerGroup, KeyExec)
 	if ok {

test/e2e/quadlet/noimage.container

@@ -1,4 +1,4 @@
 ## assert-failed
-## assert-stderr-contains "no Image key specified"
+## assert-stderr-contains "no Image or Rootfs key specified"
 
 [Container]

test/e2e/quadlet/rootfs.container

@@ -0,0 +1,4 @@
+## assert-podman-final-args "--rootfs" "/var/lib/foobar"
+
+[Container]
+Rootfs=/var/lib/foobar

test/e2e/quadlet_test.go

@@ -460,6 +460,7 @@ var _ = Describe("quadlet system generator", func() {
 		Entry("noimage.container", "noimage.container"),
 		Entry("notify.container", "notify.container"),
 		Entry("oneshot.container", "oneshot.container"),
+		Entry("rootfs.container", "rootfs.container"),
 		Entry("other-sections.container", "other-sections.container"),
 		Entry("podmanargs.container", "podmanargs.container"),
 		Entry("ports.container", "ports.container"),

test/system/252-quadlet.bats

@@ -406,4 +406,23 @@ EOF
     run_podman rmi $(pause_image)
 }
 
+@test "quadlet - rootfs" {
+    skip_if_no_selinux
+    skip_if_rootless
+    local quadlet_file=$PODMAN_TMPDIR/basic_$(random_string).container
+    cat > $quadlet_file <<EOF
+[Container]
+Rootfs=/:O
+Exec=sh -c "echo STARTED CONTAINER; echo "READY=1" | socat -u STDIN unix-sendto:\$NOTIFY_SOCKET; top"
+EOF
+
+    run_quadlet "$quadlet_file"
+    service_setup $QUADLET_SERVICE_NAME
+
+    # Ensure we have output. Output is synced via sd-notify (socat in Exec)
+    run journalctl "--since=$STARTED_TIME" --unit="$QUADLET_SERVICE_NAME"
+    is "$output" '.*STARTED CONTAINER.*'
+}
+
+
 # vim: filetype=sh