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

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
Signed by: adphi
GPG Key ID: F2159213400E50AB
7 changed files with 1664 additions and 65 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

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 {

17
convert.go
View File

@ -60,24 +60,13 @@ func Convert(ctx context.Context, img string, size int64, password string, outpu
return err
}
defer docker.Cmd(ctx, "image", "rm", imgUUID)
archive := imgUUID + ".tar"
archivePath := filepath.Join(tmpPath, archive)
logrus.Infof("creating root file system archive")
if err := docker.Cmd(ctx, "run", "-d", "--name", imgUUID, imgUUID); err != nil {
return err
}
if err := docker.Cmd(ctx, "export", "--output", archivePath, imgUUID); err != nil {
return err
}
if err := docker.Cmd(ctx, "rm", "-f", imgUUID); err != nil {
return err
}
logrus.Infof("creating vm image")
b, err := NewBuilder(tmpPath, archivePath, "", size, r, format)
logrus.Infof("creating vm image")
b, err := NewBuilder(ctx, tmpPath, imgUUID, "", size, r, format)
if err != nil {
return err
}
defer b.Close()
if err := b.Build(ctx); err != nil {
return err
}

131
docker_image.go
View File

@ -15,58 +15,127 @@
package d2vm
import (
"context"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"text/template"
"github.com/google/go-containerregistry/cmd/crane/cmd"
"github.com/google/go-containerregistry/pkg/name"
v1 "github.com/google/go-containerregistry/pkg/v1"
"github.com/google/go-containerregistry/pkg/v1/daemon"
"github.com/google/go-containerregistry/pkg/v1/mutate"
"go.linka.cloud/d2vm/pkg/exec"
)
const (
dockerImageRun = `
#!/bin/sh
{{- range .Config.Env }}
{{- range .DockerImageConfig.Env }}
export {{ . }}
{{- end }}
cd {{- if .Config.WorkingDir }}{{ .Config.WorkingDir }}{{- else }}/{{- end }}
{{ if .DockerImageConfig.WorkingDir }}cd {{ .DockerImageConfig.WorkingDir }}{{ end }}
{{ .Config.Entrypoint }} {{ .Config.Args }}
{{ if .DockerImageConfig.User }}su {{ .DockerImageConfig.User }} -p -s /bin/sh -c '{{ end }}{{ if .DockerImageConfig.Entrypoint}}{{ format .DockerImageConfig.Entrypoint }} {{ end}}{{ if .DockerImageConfig.Cmd }}{{ format .DockerImageConfig.Cmd }}{{ end }}{{ if .DockerImageConfig.User }}'{{- end }}
`
)
var (
dockerImageRunTemplate = template.Must(template.New("docker-run.sh").Parse(dockerImageRun))
dockerImageRunTemplate = template.Must(template.New("docker-run.sh").Funcs(map[string]interface{}{"format": func(a []string) string {
var o []string
for _, v := range a {
o = append(o, fmt.Sprintf("\"%s\"", v))
}
return strings.Join(o, " ")
}}).Parse(dockerImageRun))
_ = cmd.NewCmdFlatten
)
type DockerImage struct {
Config struct {
Hostname string `json:"Hostname"`
Domainname string `json:"Domainname"`
User string `json:"User"`
AttachStdin bool `json:"AttachStdin"`
AttachStdout bool `json:"AttachStdout"`
AttachStderr bool `json:"AttachStderr"`
ExposedPorts struct {
Tcp struct {
} `json:"3000/tcp"`
} `json:"ExposedPorts"`
Tty bool `json:"Tty"`
OpenStdin bool `json:"OpenStdin"`
StdinOnce bool `json:"StdinOnce"`
Env []string `json:"Env"`
Cmd []string `json:"Cmd"`
Image string `json:"Image"`
Volumes interface{} `json:"Volumes"`
WorkingDir string `json:"WorkingDir"`
Entrypoint []string `json:"Entrypoint"`
OnBuild interface{} `json:"OnBuild"`
Labels interface{} `json:"Labels"`
} `json:"Config"`
Architecture string `json:"Architecture"`
Os string `json:"Os"`
Size int `json:"Size"`
VirtualSize int `json:"VirtualSize"`
DockerImageConfig `json:"Config"`
Architecture string `json:"Architecture"`
Os string `json:"Os"`
Size int `json:"Size"`
}
type DockerImageConfig struct {
Image string `json:"Image"`
Hostname string `json:"Hostname"`
Domainname string `json:"Domainname"`
User string `json:"User"`
Env []string `json:"Env"`
Cmd []string `json:"Cmd"`
WorkingDir string `json:"WorkingDir"`
Entrypoint []string `json:"Entrypoint"`
}
func (i DockerImage) AsRunScript(w io.Writer) error {
return dockerImageRunTemplate.Execute(w, i)
}
const (
whiteoutPrefix = ".wh."
manifest = "manifest.json"
)
func NewImage(ctx context.Context, tag string, imageTmpPath string) (*image, error) {
ref, err := name.ParseReference(tag)
if err != nil {
return nil, err
}
img, err := daemon.Image(ref)
if err != nil {
return nil, err
}
if err := os.MkdirAll(imageTmpPath, perm); err != nil {
return nil, err
}
i := &image{
img: img,
dir: imageTmpPath,
}
return i, nil
}
type image struct {
tag string
img v1.Image
dir string
Config string `json:"Config"`
RepoTags []string `json:"RepoTags"`
Layers []string `json:"Layers"`
}
func (i image) Flatten(ctx context.Context, out string) error {
if err := os.MkdirAll(out, perm); err != nil {
return err
}
tar := filepath.Join(i.dir, "img.tar")
f, err := os.Create(tar)
if err != nil {
return err
}
defer f.Close()
if _, err := io.Copy(f, mutate.Extract(i.img)); err != nil {
return err
}
if err := f.Close(); err != nil {
return err
}
if err := exec.Run(ctx, "tar", "xvf", tar, "-C", out); err != nil {
return err
}
return nil
}
func (i image) Close() error {
return os.RemoveAll(i.dir)
}

171
docker_image_test.go Normal file
View File

@ -0,0 +1,171 @@
package d2vm
import (
"bytes"
"context"
"os"
"path/filepath"
"testing"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
"go.linka.cloud/d2vm/pkg/docker"
"go.linka.cloud/d2vm/pkg/exec"
)
func TestDockerImageAsRunSript(t *testing.T) {
tests := []struct {
name string
image DockerImage
want string
}{
{
name: "nothing",
image: DockerImage{
DockerImageConfig: DockerImageConfig{
User: "",
WorkingDir: "",
Env: nil,
Entrypoint: nil,
Cmd: nil,
},
},
want: `
#!/bin/sh
`,
},
{
name: "tail -f /dev/null",
image: DockerImage{
DockerImageConfig: DockerImageConfig{
User: "root",
Cmd: []string{"tail", "-f", "/dev/null"},
},
},
want: `
#!/bin/sh
su root -p -s /bin/sh -c '"tail" "-f" "/dev/null"'
`,
},
{
name: "tail -f /dev/null inside home",
image: DockerImage{
DockerImageConfig: DockerImageConfig{
User: "root",
WorkingDir: "/root",
Cmd: []string{"tail", "-f", "/dev/null"},
},
},
want: `
#!/bin/sh
cd /root
su root -p -s /bin/sh -c '"tail" "-f" "/dev/null"'
`,
},
{
name: "subshell tail -f /dev/null",
image: DockerImage{
DockerImageConfig: DockerImageConfig{
User: "root",
Entrypoint: []string{"/bin/sh", "-c"},
Cmd: []string{"tail -f /dev/null"},
},
},
want: `
#!/bin/sh
su root -p -s /bin/sh -c '"/bin/sh" "-c" "tail -f /dev/null"'
`,
},
{
name: "www-data with env",
image: DockerImage{
DockerImageConfig: DockerImageConfig{
User: "www-data",
Cmd: []string{"tail", "-f", "/dev/null"},
Env: []string{"ENV=PROD", "DB=mysql://user:password@localhost"},
},
},
want: `
#!/bin/sh
export ENV=PROD
export DB=mysql://user:password@localhost
su www-data -p -s /bin/sh -c '"tail" "-f" "/dev/null"'
`,
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
var w bytes.Buffer
require.NoError(t, tt.image.AsRunScript(&w))
assert.Equal(t, tt.want, w.String())
})
}
}
func TestImageFlatten(t *testing.T) {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
const (
img = "d2vm-flatten-test"
dockerfile = `FROM alpine
COPY resolv.conf /etc/
COPY hostname /etc/
RUN rm -rf /etc/apk
`
)
exec.Run = exec.RunStdout
tmp := filepath.Join(os.TempDir(), "d2vm-tests", "image-flatten")
require.NoError(t, os.MkdirAll(tmp, perm))
defer os.RemoveAll(tmp)
require.NoError(t, os.WriteFile(filepath.Join(tmp, "hostname"), []byte("d2vm-flatten-test"), perm))
require.NoError(t, os.WriteFile(filepath.Join(tmp, "resolv.conf"), []byte("nameserver 8.8.8.8"), perm))
require.NoError(t, os.WriteFile(filepath.Join(tmp, "Dockerfile"), []byte(dockerfile), perm))
require.NoError(t, docker.Cmd(ctx, "image", "build", "-t", img, tmp))
defer docker.Cmd(ctx, "image", "rm", img)
// imgTar := filepath.Join(tmp, img+".tar")
// require.NoError(t, docker.Cmd(ctx, "image", "save", img, "-o", imgTar))
//
imgTmp := filepath.Join(tmp, "image")
i, err := NewImage(ctx, img, imgTmp)
require.NoError(t, err)
rootfs := filepath.Join(tmp, "rootfs")
require.NoError(t, i.Flatten(ctx, rootfs))
b, err := os.ReadFile(filepath.Join(rootfs, "etc", "resolv.conf"))
require.NoError(t, err)
assert.Equal(t, "nameserver 8.8.8.8", string(b))
b, err = os.ReadFile(filepath.Join(rootfs, "etc", "hostname"))
require.NoError(t, err)
assert.Equal(t, "d2vm-flatten-test", string(b))
_, err = os.Stat(filepath.Join(rootfs, "etc", "apk"))
assert.Error(t, err)
require.NoError(t, i.Close())
_, err = os.Stat(imgTmp)
assert.Error(t, err)
}

30
go.mod
View File

@ -4,16 +4,44 @@ go 1.17
require (
github.com/c2h5oh/datasize v0.0.0-20200825124411-48ed595a09d2
github.com/google/go-containerregistry v0.8.0
github.com/google/uuid v1.3.0
github.com/joho/godotenv v1.4.0
github.com/sirupsen/logrus v1.8.1
github.com/spf13/cobra v1.4.0
github.com/stretchr/testify v1.7.0
go.uber.org/multierr v1.8.0
)
require (
github.com/Microsoft/go-winio v0.5.1 // indirect
github.com/containerd/containerd v1.5.8 // indirect
github.com/containerd/stargz-snapshotter/estargz v0.10.1 // indirect
github.com/davecgh/go-spew v1.1.1 // indirect
github.com/docker/cli v20.10.12+incompatible // indirect
github.com/docker/distribution v2.7.1+incompatible // indirect
github.com/docker/docker v20.10.12+incompatible // indirect
github.com/docker/docker-credential-helpers v0.6.4 // indirect
github.com/docker/go-connections v0.4.0 // indirect
github.com/docker/go-units v0.4.0 // indirect
github.com/gogo/protobuf v1.3.2 // indirect
github.com/golang/protobuf v1.5.2 // indirect
github.com/google/go-cmp v0.5.6 // indirect
github.com/inconshreveable/mousetrap v1.0.0 // indirect
github.com/klauspost/compress v1.13.6 // indirect
github.com/mitchellh/go-homedir v1.1.0 // indirect
github.com/opencontainers/go-digest v1.0.0 // indirect
github.com/opencontainers/image-spec v1.0.2-0.20211117181255-693428a734f5 // indirect
github.com/pkg/errors v0.9.1 // indirect
github.com/pmezard/go-difflib v1.0.0 // indirect
github.com/spf13/pflag v1.0.5 // indirect
github.com/vbatts/tar-split v0.11.2 // indirect
go.uber.org/atomic v1.7.0 // indirect
golang.org/x/sys v0.0.0-20191026070338-33540a1f6037 // indirect
golang.org/x/net v0.0.0-20211216030914-fe4d6282115f // indirect
golang.org/x/sync v0.0.0-20210220032951-036812b2e83c // indirect
golang.org/x/sys v0.0.0-20211216021012-1d35b9e2eb4e // indirect
google.golang.org/genproto v0.0.0-20211208223120-3a66f561d7aa // indirect
google.golang.org/grpc v1.43.0 // indirect
google.golang.org/protobuf v1.27.1 // indirect
gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
)

1324
go.sum
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File diff suppressed because it is too large Load Diff

2
virtinst
View File

@ -3,4 +3,4 @@
IMG=${1:-disk0.qcow2}
virt-install --disk $IMG --import --memory 4096 --vcpus 4 --nographics --cpu host --channel unix,target.type=virtio,target.name='org.qemu.guest_agent.0'
virt-install --disk $IMG --import --memory 4096 --vcpus 4 --nographics --cpu host --channel unix,target.type=virtio,target.name='org.qemu.guest_agent.0' --transient