vm: add support for custom disk images

Signed-off-by: Abiola Ibrahim <[email protected]>

cmd/start.go

@@ -163,6 +163,7 @@ func init() {
 	startCmd.Flags().StringVarP(&startCmdArgs.Arch, "arch", "a", defaultArch, "architecture (aarch64, x86_64)")
 	startCmd.Flags().BoolVarP(&startCmdArgs.Flags.Foreground, "foreground", "f", false, "Keep colima in the foreground")
 	startCmd.Flags().StringVar(&startCmdArgs.Hostname, "hostname", "", "custom hostname for the virtual machine")
+	startCmd.Flags().StringVarP(&startCmdArgs.DiskImage, "disk-image", "i", "", "local path or URL to a custom disk image")
 
 	// host IP addresses
 	startCmd.Flags().BoolVar(&startCmdArgs.Network.HostAddresses, "network-host-addresses", false, "support port forwarding to specific host IP addresses")

config/config.go

@@ -44,6 +44,7 @@ type Config struct {
 	VMType               string `yaml:"vmType,omitempty"`
 	VZRosetta            bool   `yaml:"rosetta,omitempty"`
 	NestedVirtualization bool   `yaml:"nestedVirtualization,omitempty"`
+	DiskImage            string `yaml:"diskImage,omitempty"`
 
 	// volume mounts
 	Mounts       []Mount `yaml:"mounts,omitempty"`

embedded/defaults/colima.yaml

@@ -197,6 +197,14 @@ sshPort: 0
 # Default: []
 mounts: []
 
+# Specify a custom disk image for the virtual machine.
+# When not specified, Colima downloads the disk image from Github at
+# https://github.com/abiosoft/colima-core/releases.
+# A custom disk image (local disk path or URL) can be specified to override the behaviour.
+#
+# Default: ""
+diskImage: ""
+
 # Environment variables for the virtual machine.
 #
 # EXAMPLE

environment/vm/lima/lima.go

@@ -274,11 +274,26 @@ func (l limaVM) Arch() environment.Arch {
 func (l *limaVM) downloadDiskImage(ctx context.Context, conf config.Config) error {
 	log := l.Logger(ctx)
 
+	// use a previously cached image
 	if image, ok := limautil.ImageCached(l.limaConf.Arch, conf.Runtime); ok {
 		l.limaConf.Images = []limaconfig.File{image}
 		return nil
 	}
 
+	// use a user specified disk image
+	if conf.DiskImage != "" {
+		log.Infoln("using specified disk image ...")
+		image, err := limautil.Image(l.limaConf.Arch, conf.Runtime)
+		if err != nil {
+			return fmt.Errorf("error getting disk image details: %w", err)
+		}
+		log.Warnf("disk image must be identical to '%s'", image.Location)
+		image.Location = conf.DiskImage
+		l.limaConf.Images = []limaconfig.File{image}
+		return nil
+	}
+
+	// download image
 	log.Infoln("downloading disk image ...")
 	image, err := limautil.DownloadImage(l.limaConf.Arch, conf.Runtime)
 	if err != nil {

environment/vm/lima/limautil/image.go

@@ -53,6 +53,11 @@ func findImage(arch environment.Arch, runtime string) (f limaconfig.File, err er
 	return img, nil
 }
 
+// Image returns the details of the disk image to download for the arch and runtime.
+func Image(arch environment.Arch, runtime string) (limaconfig.File, error) {
+	return findImage(arch, runtime)
+}
+
 // DownloadImage downloads the image for arch and runtime.
 func DownloadImage(arch environment.Arch, runtime string) (f limaconfig.File, err error) {
 	img, err := findImage(arch, runtime)