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Code Issues Releases Activity

d2vm: flatten docker image using github.com/google/go-containerregistry

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This allows to preserve files like /etc/hostname or /etc/resolv.conf that will otherwise be overriden by running the container to extract rootfs

wip img entrypoint script

Signed-off-by: Adphi <philippe.adrien.nousse@gmail.com>
This commit is contained in:
adphi
2022-04-24 15:49:01 +02:00
parent 0c9bfb6dd8
commit 20ba409039
7 changed files with 1664 additions and 65 deletions
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54
builder.go
View File

@@ -18,7 +18,6 @@ import (
"bytes"
"context"
"fmt"
"math"
"os"
exec2 "os/exec"
"path/filepath"
@@ -85,10 +84,15 @@ var (
}
)
const (
perm os.FileMode = 0644
)
type builder struct {
osRelease OSRelease
src string
img *image
diskRaw string
diskOut string
format string
@@ -103,7 +107,7 @@ type builder struct {
diskUUD string
}
func NewBuilder(workdir, src, disk string, size int64, osRelease OSRelease, format string) (*builder, error) {
func NewBuilder(ctx context.Context, workdir, imgTag, disk string, size int64, osRelease OSRelease, format string) (*builder, error) {
if err := checkDependencies(); err != nil {
return nil, err
}
@@ -134,18 +138,22 @@ func NewBuilder(workdir, src, disk string, size int64, osRelease OSRelease, form
if disk == "" {
disk = "disk0"
}
i, err := os.Stat(src)
img, err := NewImage(ctx, imgTag, workdir)
if err != nil {
return nil, err
}
if i.Size() > size {
s := datasize.ByteSize(math.Ceil(datasize.ByteSize(i.Size()).GBytes())) * datasize.GB
logrus.Warnf("%s is smaller than rootfs size, using %s", datasize.ByteSize(size), s)
size = int64(s)
}
// i, err := os.Stat(imgTar)
// if err != nil {
// return nil, err
// }
// if i.Size() > size {
// s := datasize.ByteSize(math.Ceil(datasize.ByteSize(i.Size()).GBytes())) * datasize.GB
// logrus.Warnf("%s is smaller than rootfs size, using %s", datasize.ByteSize(size), s)
// size = int64(s)
// }
b := &builder{
osRelease: osRelease,
src: src,
img: img,
diskRaw: filepath.Join(workdir, disk+".raw"),
diskOut: filepath.Join(workdir, disk+".qcow2"),
format: f,
@@ -271,7 +279,7 @@ func (b *builder) unmountImg(ctx context.Context) error {
func (b *builder) copyRootFS(ctx context.Context) error {
logrus.Infof("copying rootfs to raw image")
if err := exec.Run(ctx, "tar", "-xvf", b.src, "-C", b.mntPoint); err != nil {
if err := b.img.Flatten(ctx, b.mntPoint); err != nil {
return err
}
return nil
@@ -285,18 +293,19 @@ func (b *builder) setupRootFS(ctx context.Context) error {
}
b.diskUUD = strings.TrimSuffix(o, "\n")
fstab := fmt.Sprintf("UUID=%s / ext4 errors=remount-ro 0 1\n", b.diskUUD)
if err := b.chWriteFile("/etc/fstab", fstab, 0644); err != nil {
if err := b.chWriteFile("/etc/fstab", fstab, perm); err != nil {
return err
}
if err := b.chWriteFile("/etc/resolv.conf", "nameserver 8.8.8.8", 0644); err != nil {
if err := b.chWriteFileIfNotExist("/etc/resolv.conf", "nameserver 8.8.8.8", 0644); err != nil {
return err
}
if err := b.chWriteFile("/etc/hostname", "localhost", 0644); err != nil {
if err := b.chWriteFileIfNotExist("/etc/hostname", "localhost", perm); err != nil {
return err
}
if err := b.chWriteFile("/etc/hosts", hosts, 0644); err != nil {
if err := b.chWriteFileIfNotExist("/etc/hosts", hosts, perm); err != nil {
return err
}
// TODO(adphi): is it the righ fix ?
if err := os.RemoveAll("/ur/sbin/policy-rc.d"); err != nil {
return err
}
@@ -311,10 +320,10 @@ func (b *builder) setupRootFS(ctx context.Context) error {
return err
}
by = append(by, []byte("\n"+"ttyS0::respawn:/sbin/getty -L ttyS0 115200 vt100\n")...)
if err := b.chWriteFile("/etc/inittab", string(by), 0644); err != nil {
if err := b.chWriteFile("/etc/inittab", string(by), perm); err != nil {
return err
}
if err := b.chWriteFile("/etc/network/interfaces", "", 0644); err != nil {
if err := b.chWriteFileIfNotExist("/etc/network/interfaces", "", perm); err != nil {
return err
}
return nil
@@ -338,7 +347,7 @@ func (b *builder) installKernel(ctx context.Context) error {
default:
return fmt.Errorf("%s: distribution not supported", b.osRelease.ID)
}
if err := b.chWriteFile("/boot/syslinux.cfg", fmt.Sprintf(sysconfig, b.diskUUD), 0644); err != nil {
if err := b.chWriteFile("/boot/syslinux.cfg", fmt.Sprintf(sysconfig, b.diskUUD), perm); err != nil {
return err
}
return nil
@@ -361,10 +370,21 @@ func (b *builder) chWriteFile(path string, content string, perm os.FileMode) err
return os.WriteFile(b.chPath(path), []byte(content), perm)
}
func (b *builder) chWriteFileIfNotExist(path string, content string, perm os.FileMode) error {
if i, err := os.Stat(b.chPath(path)); err == nil && i.Size() != 0 {
return nil
}
return os.WriteFile(b.chPath(path), []byte(content), perm)
}
func (b *builder) chPath(path string) string {
return fmt.Sprintf("%s%s", b.mntPoint, path)
}
func (b *builder) Close() error {
return b.img.Close()
}
func block(path string, size int64) error {
f, err := os.Create(path)
if err != nil {