build-disk command (#1794)

This commit adds in elemental client the build-disk command. With this command we can eventually build an image that includes partitions:

* EFI
* OEM
* Recovery
* State

Having State partition to match the minimum size (to reduce resulting image size), only includes config files no image.

Then the State partition could be expanded on first boot to desired size (build-disk command already pre-appends the required cloud-config files for that to happen) and then the Persistent partition created at the end with all the available space (or some desired specific size too).

This setup can be executed without running a single mount (thanks to squashfs usage), meaning this disk could be built in a container or Dockerfile (like we do with ISOs).

Building full disks including all partitions with an specified size is still possible, however this approach requires mount privileges and because of that it can't be executed inside non privileged containers.


Signed-off-by: David Cassany <[email protected]>

cmd/build-disk.go

@@ -0,0 +1,120 @@
+/*
+Copyright © 2022 - 2023 SUSE LLC
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cmd
+
+import (
+	"os/exec"
+
+	"github.com/rancher/elemental-toolkit/pkg/constants"
+	eleError "github.com/rancher/elemental-toolkit/pkg/error"
+	elementalError "github.com/rancher/elemental-toolkit/pkg/error"
+	v1 "github.com/rancher/elemental-toolkit/pkg/types/v1"
+
+	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+	"k8s.io/mount-utils"
+
+	"github.com/rancher/elemental-toolkit/cmd/config"
+	"github.com/rancher/elemental-toolkit/pkg/action"
+)
+
+// NewBuildDisk returns a new instance of the build-disk subcommand and appends it to
+// the root command. requireRoot is to initiate it with or without the CheckRoot
+// pre-run check. This method is mostly used for testing purposes.
+func NewBuildDisk(root *cobra.Command, addCheckRoot bool) *cobra.Command {
+	c := &cobra.Command{
+		Use:   "build-disk image",
+		Short: "Build a disk image using the given image (experimental and subject to change)",
+		Args:  cobra.MaximumNArgs(1),
+		PreRunE: func(cmd *cobra.Command, args []string) error {
+			if addCheckRoot {
+				return CheckRoot()
+			}
+			return nil
+		},
+		RunE: func(cmd *cobra.Command, args []string) (err error) {
+			var cfg *v1.BuildConfig
+			var spec *v1.Disk
+			var imgSource *v1.ImageSource
+
+			defer func() {
+				if cfg != nil && err != nil {
+					cfg.Logger.Errorf("Woophs, something went terribly wrong: %s", err)
+				}
+			}()
+
+			path, err := exec.LookPath("mount")
+			if err != nil {
+				return err
+			}
+			mounter := mount.New(path)
+
+			flags := cmd.Flags()
+			cfg, err = config.ReadConfigBuild(viper.GetString("config-dir"), flags, mounter)
+			if err != nil {
+				return eleError.NewFromError(err, eleError.ReadingBuildConfig)
+			}
+
+			err = validateCosignFlags(cfg.Logger, flags)
+			if err != nil {
+				return eleError.NewFromError(err, eleError.CosignWrongFlags)
+			}
+
+			// Set this after parsing of the flags, so it fails on parsing and prints usage properly
+			cmd.SilenceUsage = true
+			cmd.SilenceErrors = true // Do not propagate errors down the line, we control them
+
+			spec, err = config.ReadBuildDisk(cfg, flags)
+			if err != nil {
+				cfg.Logger.Errorf("invalid install command setup %v", err)
+				return eleError.NewFromError(err, eleError.ReadingBuildDiskConfig)
+			}
+
+			if len(args) > 0 {
+				imgSource, err = v1.NewSrcFromURI(args[0])
+				if err != nil {
+					cfg.Logger.Errorf("not a valid image argument: %s", args[0])
+					return elementalError.NewFromError(err, elementalError.IdentifySource)
+				}
+				spec.Recovery.Source = imgSource
+			}
+
+			// TODO add logic for an already existing output file
+
+			builder := action.NewBuildDiskAction(cfg, spec)
+
+			return builder.BuildDiskRun()
+		},
+	}
+	root.AddCommand(c)
+	imgType := newEnumFlag([]string{constants.RawType, constants.AzureType, constants.GCEType}, constants.RawType)
+	c.Flags().StringP("name", "n", "", "Basename of the generated disk file")
+	c.Flags().StringP("output", "o", "", "Output directory (defaults to current directory)")
+	c.Flags().Bool("date", false, "Adds a date suffix into the generated disk file")
+	c.Flags().Bool("expandable", false, "Creates an expandable image including only the recovery image")
+	c.Flags().Bool("unprivileged", false, "Makes a build runnable within a non-privileged container, avoids mounting filesystems (experimental)")
+	c.Flags().VarP(imgType, "type", "t", "Type of image to create")
+	// TODO verify if cross-arch builds make any sense
+	//addArchFlags(c)
+	addLocalImageFlag(c)
+	addSquashFsCompressionFlags(c)
+	addCosignFlags(c)
+	return c
+}
+
+// register the subcommand into rootCmd
+var _ = NewBuildDisk(rootCmd, true)

cmd/config/config.go

@@ -319,6 +319,26 @@ func ReadBuildISO(b *v1.BuildConfig, flags *pflag.FlagSet) (*v1.LiveISO, error)
 	return iso, err
 }
 
+func ReadBuildDisk(b *v1.BuildConfig, flags *pflag.FlagSet) (*v1.Disk, error) {
+	disk := config.NewDisk(b)
+	vp := viper.Sub("disk")
+	if vp == nil {
+		vp = viper.New()
+	}
+	// Bind build-disk cmd flags
+	bindGivenFlags(vp, flags)
+	// Bind build-disk env vars
+	viperReadEnv(vp, "DISK", constants.GetDiskKeyEnvMap())
+
+	err := vp.Unmarshal(disk, setDecoder, decodeHook)
+	if err != nil {
+		b.Logger.Warnf("error unmarshalling Disk: %s", err)
+	}
+	err = disk.Sanitize()
+	b.Logger.Debugf("Loaded Disk: %s", litter.Sdump(disk))
+	return disk, err
+}
+
 func configLogger(log v1.Logger, vfs v1.FS) {
 	// Set debug level
 	if viper.GetBool("debug") {

cmd/config/config_test.go

@@ -179,6 +179,19 @@ var _ = Describe("Config", Label("config"), func() {
 				Expect(iso.Label).To(Equal("LIVE_LABEL"))
 			})
 		})
+		Describe("RawDisk spec", Label("disk"), func() {
+			It("initiates a RawDisk spec", func() {
+				disk, err := ReadBuildDisk(cfg, nil)
+				Expect(err).ShouldNot(HaveOccurred())
+
+				// From config file
+				Expect(disk.Size).To(Equal(uint(32768)))
+				Expect(disk.Partitions.OEM.Size).To(Equal(uint(32)))
+				Expect(disk.Unprivileged).To(BeTrue())
+				Expect(disk.Expandable).To(BeTrue())
+				Expect(disk.Recovery.Label).To(BeEmpty())
+			})
+		})
 	})
 	Describe("Run config", Label("run"), func() {
 		var flags *pflag.FlagSet

cmd/config/fixtures/config/manifest.yaml

@@ -7,5 +7,24 @@ iso:
     - oci:recovery/cos-img
   label: "LIVE_LABEL"
 
+disk:
+  size: 32768
+  partitions:
+    oem:
+      size: 32
+    state:
+      size: 8192
+    recovery:
+      size: 2048
+    persistent:
+      size: 0
+      fs: xfs
+  unprivileged: true
+  expandable: true
+  recovery-system:
+    uri: some.registry.org/my/image:mytag
+    fs: squashfs
+  type: raw
+
 name: "cOS-0"
 date: true