disk: Recreate the bootc disk image when passed certain parameters

Sometimes the disk image needs to be recreated even if reusing
the same container image, for example when passing --disk-size
to create a bootc disk with a larger disk size.

Signed-off-by: Chris Kyrouac <[email protected]>

Author: ckyrouac

cmd/run.go

@@ -136,8 +136,16 @@ func doRun(flags *cobra.Command, args []string) error {
 		return fmt.Errorf("VM already running, use the ssh command to connect to it")
 	}
 
+	// if any of these parameters are set, we need to rebuild the disk image if one exists
+	bustCache := false
+	if diskImageConfigInstance.DiskSize != "" ||
+		diskImageConfigInstance.RootSizeMax != "" ||
+		diskImageConfigInstance.Filesystem != "" {
+		bustCache = true
+	}
+
 	// create the disk image
-	bootcDisk := bootc.NewBootcDisk(containerImage, ctx, user, cache)
+	bootcDisk := bootc.NewBootcDisk(containerImage, ctx, user, cache, bustCache)
 	err = bootcDisk.Install(vmConfig.Quiet, diskImageConfigInstance)
 
 	if err != nil {

pkg/bootc/bootc_disk.go

@@ -68,6 +68,7 @@ type BootcDisk struct {
 	CreatedAt               time.Time
 	file                    *os.File
 	bootcInstallContainerId string
+	bustCache               bool
 }
 
 // create singleton for easy cleanup
@@ -82,13 +83,16 @@ var (
 //   - imageNameOrId: the name or id of the container image
 //   - ctx: context for the podman machine connection
 //   - user: the user who is running the command, determines where the disk image is stored
-func NewBootcDisk(containerImage container.ContainerImage, ctx context.Context, user user.User, cache cache.Cache) *BootcDisk {
+//   - cache: the cache to use for storing the disk image
+//   - bustCache: whether to force a new disk image to be created
+func NewBootcDisk(containerImage container.ContainerImage, ctx context.Context, user user.User, cache cache.Cache, bustCache bool) *BootcDisk {
 	instanceOnce.Do(func() {
 		instance = &BootcDisk{
 			ContainerImage: containerImage,
 			Ctx:            ctx,
 			User:           user,
 			Cache:          cache,
+			bustCache:      bustCache,
 		}
 	})
 	return instance
@@ -146,13 +150,25 @@ func (p *BootcDisk) getOrInstallImageToDisk(quiet bool, diskConfig DiskImageConf
 		logrus.Debugf("No existing disk image found")
 		return p.bootcInstallImageToDisk(quiet, diskConfig)
 	}
+	if p.bustCache {
+		logrus.Debug("Found existing disk image but cache busting is enabled, removing and recreating")
+		err = os.Remove(diskPath)
+		if err != nil {
+			return err
+		}
+		return p.bootcInstallImageToDisk(quiet, diskConfig)
+	}
+
 	logrus.Debug("Found existing disk image, comparing digest")
 	defer f.Close()
 	buf := make([]byte, 4096)
 	len, err := unix.Fgetxattr(int(f.Fd()), imageMetaXattr, buf)
 	if err != nil {
 		// If there's no xattr, just remove it
-		os.Remove(diskPath)
+		err = os.Remove(diskPath)
+		if err != nil {
+			return err
+		}
 		logrus.Debugf("No %s xattr found", imageMetaXattr)
 		return p.bootcInstallImageToDisk(quiet, diskConfig)
 	}

podman-bootc.go

@@ -59,7 +59,7 @@ func cleanup() {
 	}
 
 	//delete the disk image
-	err = bootc.NewBootcDisk(container.ContainerImage{}, ctx, user, cache.Cache{}).Cleanup()
+	err = bootc.NewBootcDisk(container.ContainerImage{}, ctx, user, cache.Cache{}, false).Cleanup()
 	if err != nil {
 		logrus.Errorf("unable to get podman machine info: %s", err)
 		os.Exit(0)

test/e2e/e2e_test.go

@@ -315,4 +315,62 @@ var _ = Describe("E2E", func() {
 			}
 		})
 	})
+
+
+	Context("Modifying disk size", Ordered, func() {
+		var vm *e2e.TestVM
+
+		BeforeAll(func() {
+			var err error
+			vm, err = e2e.BootVM(e2e.BaseImage, "--disk-size", "25G")
+			Expect(err).To(Not(HaveOccurred()))
+		})
+
+		It("Should create a new VM with a specific disk size", func() {
+			vmDirs, err := e2e.ListCacheDirs()
+			Expect(err).To(Not(HaveOccurred()))
+			Expect(vmDirs).To(HaveLen(1))
+
+			fileInfo, err := os.Stat(filepath.Join(vmDirs[0], config.DiskImage))
+			Expect(err).To(Not(HaveOccurred()))
+
+			Expect(fileInfo.Size()).To(Equal(int64(25000001536)))
+		})
+
+		It("Should fail to resize a VM's disk size while the VM is running", func() {
+			_, _, err := e2e.RunPodmanBootc("run", e2e.BaseImage, "--disk-size", "26G")
+			Expect(err).To(HaveOccurred())
+		})
+
+		It("Should resize an existing VM's disk size", func() {
+			//stop the VM first
+			err := vm.StdIn.Close()
+			Expect(err).To(Not(HaveOccurred()))
+			_, _, err = e2e.RunPodmanBootc("stop", vm.Id)
+			Expect(err).To(Not(HaveOccurred()))
+
+			Eventually(func() bool {
+				vmExists, err := e2e.VMExists(vm.Id)
+				Expect(err).To(Not(HaveOccurred()))
+				return vmExists
+			}).Should(BeFalse())
+
+			//resize the disk
+			vm, err = e2e.BootVM(e2e.BaseImage, "--disk-size", "27G")
+			Expect(err).To(Not(HaveOccurred()))
+
+			//verify the disk size
+			vmDirs, err := e2e.ListCacheDirs()
+			Expect(err).To(Not(HaveOccurred()))
+			Expect(vmDirs).To(HaveLen(1))
+			fileInfo, err := os.Stat(filepath.Join(vmDirs[0], config.DiskImage))
+			Expect(err).To(Not(HaveOccurred()))
+			Expect(fileInfo.Size()).To(Equal(int64(27000000512)))
+		})
+
+		AfterAll(func() {
+			vm.StdIn.Close()
+			e2e.Cleanup()
+		})
+	})
 })

test/e2e/e2e_utils.go

@@ -105,8 +105,10 @@ func GetVMIdFromContainerImage(image string) (vmId string, err error) {
 	return
 }
 
-func BootVM(image string) (vm *TestVM, err error) {
-	runActiveCmd := exec.Command(PodmanBootcBinary(), "run", image)
+func BootVM(image string, args ...string) (vm *TestVM, err error) {
+	cmd := []string{"run", image}
+	cmd = append(cmd, args...)
+	runActiveCmd := exec.Command(PodmanBootcBinary(), cmd...)
 	stdIn, err := runActiveCmd.StdinPipe()
 
 	if err != nil {