distro/rhel8: add tar image type for all architectures

This is a very minimal image type, which is not expected to do anything
with an empty blueprint. It is documented as a way to install RHEL for
Satellite.

This fixes #720.

Signed-off-by: Tom Gundersen <teg@jklm.no>

internal/distro/rhel8/distro.go

@@ -568,6 +568,14 @@ func qemuAssembler(format string, filename string, uefi bool, imageOptions distr
 	return osbuild.NewQEMUAssembler(&options)
 }
 
+func tarAssembler(filename, compression string) *osbuild.Assembler {
+	return osbuild.NewTarAssembler(
+		&osbuild.TarAssemblerOptions{
+			Filename:    filename,
+			Compression: compression,
+		})
+}
+
 // New creates a new distro object, defining the supported architectures and image types
 func New() distro.Distro {
 	const GigaByte = 1024 * 1024 * 1024
@@ -760,6 +768,21 @@ func New() distro.Distro {
 		},
 	}
 
+	tarImgType := imageType{
+		name:     "tar",
+		filename: "root.tar.xz",
+		mimeType: "application/x-tar",
+		packages: []string{
+			"policycoreutils",
+			"selinux-policy-targeted",
+		},
+		bootable:      false,
+		kernelOptions: "ro net.ifnames=0",
+		assembler: func(uefi bool, options distro.ImageOptions, arch distro.Arch) *osbuild.Assembler {
+			return tarAssembler("root.tar.xz", "xz")
+		},
+	}
+
 	vhdImgType := imageType{
 		name:     "vhd",
 		filename: "disk.vhd",
@@ -860,6 +883,7 @@ func New() distro.Distro {
 		amiImgType,
 		qcow2ImageType,
 		openstackImgType,
+		tarImgType,
 		vhdImgType,
 		vmdkImgType,
 	)
@@ -880,6 +904,7 @@ func New() distro.Distro {
 		amiImgType,
 		qcow2ImageType,
 		openstackImgType,
+		tarImgType,
 	)
 
 	ppc64le := architecture{
@@ -900,12 +925,16 @@ func New() distro.Distro {
 	}
 	ppc64le.setImageTypes(
 		qcow2ImageType,
+		tarImgType,
 	)
 
 	s390x := architecture{
 		distro: &r,
 		name:   "s390x",
 	}
+	s390x.setImageTypes(
+		tarImgType,
+	)
 
 	r.setArches(x8664, aarch64, ppc64le, s390x)
 

internal/distro/rhel8/distro_test.go

@@ -37,6 +37,13 @@ func TestFilenameFromType(t *testing.T) {
 			want:  "disk.qcow2",
 			want1: "application/x-qemu-disk",
 		},
+		{
+			name:  "tar",
+			args:  args{"tar"},
+			want:  "root.tar.xz",
+			want1: "application/x-tar",
+		},
+
 		{
 			name:  "vhd",
 			args:  args{"vhd"},
@@ -134,6 +141,7 @@ func TestImageType_Name(t *testing.T) {
 				"ami",
 				"qcow2",
 				"openstack",
+				"tar",
 				"vhd",
 				"vmdk",
 			},
@@ -144,13 +152,21 @@ func TestImageType_Name(t *testing.T) {
 				"ami",
 				"qcow2",
 				"openstack",
+				"tar",
 			},
 		},
 		{
 			arch: "ppc64le",
+			imgNames: []string{
+				"qcow2",
+				"tar",
+			},
 		},
 		{
 			arch: "s390x",
+			imgNames: []string{
+				"tar",
+			},
 		},
 	}
 	for _, mapping := range imgMap {