Raw image modification implementation (#18)

Dockerfile

@@ -7,9 +7,14 @@ RUN go build ./cmd/eib
 
 
 # ----- Deliverable Image -----
-FROM registry.suse.com/bci/bci-base:15.5
+FROM opensuse/leap:15.5
 
-RUN zypper install -y xorriso
+# Dependency uses by line
+# 1. ISO image building
+# 2. RAW image modification on x86_64
+RUN zypper install -y \
+    xorriso  \
+    libguestfs kernel-default e2fsprogs parted gptfdisk btrfsprogs
 
 COPY --from=0 /src/eib /bin/eib
 

pkg/build/build.go

@@ -48,9 +48,18 @@ func (b *Builder) Build() error {
 		return fmt.Errorf("generating combustion script: %w", err)
 	}
 
-	err = b.buildIsoImage()
+	switch b.imageConfig.Image.ImageType {
+	case config.ImageTypeISO:
+		err = b.buildIsoImage()
+	case config.ImageTypeRAW:
+		err = b.buildRawImage()
+	default:
+		err = fmt.Errorf("invalid imageType value specified, must be either \"%s\" or \"%s\"",
+			config.ImageTypeISO, config.ImageTypeRAW)
+	}
+
 	if err != nil {
-		return fmt.Errorf("error building modified ISO: %w", err)
+		return err
 	}
 
 	err = b.cleanUpBuildDir()
@@ -154,3 +163,13 @@ func (b *Builder) registerCombustionScript(scriptName string) {
 
 	b.combustionScripts = append(b.combustionScripts, scriptName)
 }
+
+func (b *Builder) generateOutputImageFilename() string {
+	filename := filepath.Join(b.buildConfig.ImageConfigDir, b.imageConfig.Image.OutputImageName)
+	return filename
+}
+
+func (b *Builder) generateBaseImageFilename() string {
+	filename := filepath.Join(b.buildConfig.ImageConfigDir, "images", b.imageConfig.Image.BaseImage)
+	return filename
+}

pkg/build/iso.go

@@ -38,7 +38,7 @@ func (b *Builder) buildIsoImage() error {
 }
 
 func (b *Builder) deleteExistingOutputIso() error {
-	outputFilename := b.generateOutputIsoFilename()
+	outputFilename := b.generateOutputImageFilename()
 	err := os.Remove(outputFilename)
 	if err != nil && !os.IsNotExist(err) {
 		return fmt.Errorf("error deleting file %s: %w", outputFilename, err)
@@ -63,8 +63,8 @@ func (b *Builder) createXorrisoCommand() (*exec.Cmd, *os.File, error) {
 }
 
 func (b *Builder) generateXorrisoArgs() []string {
-	indevPath := filepath.Join(b.buildConfig.ImageConfigDir, "images", b.imageConfig.Image.BaseImage)
-	outdevPath := filepath.Join(b.buildConfig.ImageConfigDir, b.imageConfig.Image.OutputImageName)
+	indevPath := b.generateBaseImageFilename()
+	outdevPath := b.generateOutputImageFilename()
 	mapDir := b.combustionDir
 
 	args := fmt.Sprintf(xorrisoArgsBase, indevPath, outdevPath, mapDir)
@@ -78,8 +78,3 @@ func (b *Builder) generateIsoLogFilename() string {
 	logFilename := filepath.Join(b.eibBuildDir, filename)
 	return logFilename
 }
-
-func (b *Builder) generateOutputIsoFilename() string {
-	filename := filepath.Join(b.buildConfig.ImageConfigDir, b.imageConfig.Image.OutputImageName)
-	return filename
-}

pkg/build/iso_test.go

@@ -49,7 +49,7 @@ func TestDeleteExistingImage(t *testing.T) {
 	}
 	builder := New(&imageConfig, &buildConfig)
 
-	_, err = os.Create(builder.generateOutputIsoFilename())
+	_, err = os.Create(builder.generateOutputImageFilename())
 	require.NoError(t, err)
 
 	// Test
@@ -58,7 +58,7 @@ func TestDeleteExistingImage(t *testing.T) {
 	// Verify
 	require.NoError(t, err)
 
-	_, err = os.Stat(builder.generateOutputIsoFilename())
+	_, err = os.Stat(builder.generateOutputImageFilename())
 	require.Error(t, err)
 	require.True(t, os.IsNotExist(err))
 }

pkg/build/raw.go

@@ -0,0 +1,66 @@
+package build
+
+import (
+	_ "embed"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+)
+
+const (
+	copyExec = "/bin/cp"
+	modifyScriptName = "modify-raw-image.sh"
+)
+
+//go:embed scripts/modify-raw-image.sh
+var modifyRawImageScript string
+
+func (b *Builder) buildRawImage() error {
+	cmd := b.createRawImageCopyCommand()
+	err := cmd.Run()
+	if err != nil {
+		return fmt.Errorf("copying the base image %s to the output image location %s: %w",
+			b.imageConfig.Image.BaseImage, b.generateOutputImageFilename(), err)
+	}
+
+	err = b.writeModifyScript()
+	if err != nil {
+		return fmt.Errorf("writing the image modification script: %w", err)
+	}
+
+	cmd = b.createModifyCommand()
+	err = cmd.Run()
+	if err != nil {
+		return fmt.Errorf("running the image modification script: %w", err)
+	}
+
+	return nil
+}
+
+func (b *Builder) createRawImageCopyCommand() *exec.Cmd {
+	baseImagePath := b.generateBaseImageFilename()
+	outputImagePath := b.generateOutputImageFilename()
+
+	cmd := exec.Command(copyExec, baseImagePath, outputImagePath)
+	return cmd
+}
+
+func (b *Builder) writeModifyScript() error {
+	imageToModify := b.generateOutputImageFilename()
+	contents := fmt.Sprintf(modifyRawImageScript, imageToModify, b.combustionDir)
+
+	scriptPath := filepath.Join(b.buildConfig.BuildDir, modifyScriptName)
+	err := os.WriteFile(scriptPath, []byte(contents), os.ModePerm)
+	if err != nil {
+		return fmt.Errorf("writing file %s: %w", scriptPath, err)
+	}
+
+	return nil
+}
+
+func (b *Builder) createModifyCommand() *exec.Cmd {
+	scriptPath := filepath.Join(b.buildConfig.BuildDir, modifyScriptName)
+	cmd := exec.Command(scriptPath)
+	return cmd
+}

pkg/build/raw_test.go

@@ -0,0 +1,89 @@
+package build
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/suse-edge/edge-image-builder/pkg/config"
+)
+
+func TestCreateRawImageCopyCommand(t *testing.T) {
+	// Setup
+	imageConfig := config.ImageConfig{
+		Image: config.Image{
+			BaseImage:       "base-image",
+			OutputImageName: "build-image",
+		},
+	}
+	buildConfig := config.BuildConfig{
+		ImageConfigDir: "config-dir",
+	}
+	builder := New(&imageConfig, &buildConfig)
+
+	// Test
+	cmd := builder.createRawImageCopyCommand()
+
+	// Verify
+	require.NotNil(t, cmd)
+
+	assert.Equal(t, copyExec, cmd.Path)
+	expectedArgs := []string {
+		copyExec,
+		builder.generateBaseImageFilename(),
+		builder.generateOutputImageFilename(),
+	}
+	assert.Equal(t, expectedArgs, cmd.Args)
+}
+
+func TestWriteModifyScript(t *testing.T) {
+	// Setup
+	tmpDir, err := os.MkdirTemp("", "eib-")
+	require.NoError(t, err)
+	defer os.RemoveAll(tmpDir)
+
+	imageConfig := config.ImageConfig{
+		Image: config.Image{
+			OutputImageName: "output-image",
+		},
+	}
+	buildConfig := config.BuildConfig{
+		ImageConfigDir: "config-dir",
+		BuildDir: tmpDir,
+	}
+	builder := New(&imageConfig, &buildConfig)
+	builder.combustionDir = "combustion-dir"
+
+	// Test
+	err = builder.writeModifyScript()
+
+	// Verify
+	require.NoError(t, err)
+
+	expectedFilename := filepath.Join(tmpDir, modifyScriptName)
+	foundBytes, err := os.ReadFile(expectedFilename)
+	require.NoError(t, err)
+
+	foundContents := string(foundBytes)
+	assert.Contains(t, foundContents, "guestfish --rw -a config-dir/output-image")
+	assert.Contains(t, foundContents, "copy-in combustion-dir")
+}
+
+func TestCreateModifyCommand(t *testing.T) {
+	// Setup
+	buildConfig := config.BuildConfig{
+		BuildDir: "build-dir",
+	}
+	builder := New(nil, &buildConfig)
+
+	// Test
+	cmd := builder.createModifyCommand()
+
+	// Verify
+	require.NotNil(t, cmd)
+
+	expectedPath := filepath.Join("build-dir", modifyScriptName)
+	assert.Equal(t, expectedPath, cmd.Path)
+}

pkg/build/scripts/modify-raw-image.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+set -euo pipefail
+
+#  Substitution Fields
+#  1. Full path to the image to modify
+#  2. Full path to the combustion directory
+
+#  Guestfish Commands Explanation
+#
+#  sh "btrfs property set / ro false"
+#  - Enables write access to the read only filesystem
+#
+#  copy-in _s /
+#  - Copies the combustion directory into the root of the image
+#  - _s should be populated with the full path to the built combustion directory
+#
+#  sh "btrfs filesystem label / INSTALL"
+#  - As of Oct 25, 2023, combustion only checks volumes of certain names for the
+#    /combustion directory. The SLE Micro raw image sets the root partition name to
+#    "ROOT", which isn't one of the checked volume names. This line changes the
+#    label to "INSTALL" (the same as the ISO installer uses) so it's picked up
+#    when combustion runs.
+#
+#  sh "btrfs property set / ro true"
+#  - Resets the filesystem to read only
+
+guestfish --rw -a %s -i <<'EOF'
+  sh "btrfs property set / ro false"
+  copy-in %s /
+  sh "btrfs filesystem label / INSTALL"
+  sh "btrfs property set / ro true"
+EOF

pkg/config/image.go

@@ -6,6 +6,11 @@ import (
 	"gopkg.in/yaml.v3"
 )
 
+const (
+	ImageTypeISO = "iso"
+	ImageTypeRAW = "raw"
+)
+
 type ImageConfig struct {
 	APIVersion string `yaml:"apiVersion"`
 	Image	   Image  `yaml:"image"`