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|
package test
import (
"archive/tar"
"bytes"
"crypto/sha256"
"encoding/hex"
"encoding/json"
"io/ioutil"
"os"
"path"
"github.com/appc/docker2aci/lib/common"
"github.com/appc/docker2aci/lib/internal/typesV2"
)
type Layer map[*tar.Header][]byte
type Docker22Image struct {
RepoTags []string
Layers []Layer
Config typesV2.ImageConfig
}
func GenerateDocker22(destPath string, img Docker22Image) error {
layerHashes, err := GenLayers(destPath, img.Layers)
if err != nil {
return err
}
configHash, err := GenDocker22Config(destPath, img.Config, layerHashes)
if err != nil {
return err
}
err = GenDocker22Manifest(destPath, configHash, layerHashes)
if err != nil {
return err
}
return nil
}
func GenLayers(destPath string, layers []Layer) ([]string, error) {
var layerHashes []string
for _, l := range layers {
layerBuffer := &bytes.Buffer{}
tw := tar.NewWriter(layerBuffer)
for hdr, contents := range l {
hdr.Size = int64(len(contents))
err := tw.WriteHeader(hdr)
if err != nil {
tw.Close()
return nil, err
}
_, err = tw.Write(contents)
if err != nil {
tw.Close()
return nil, err
}
}
tw.Close()
layerTarBlob := layerBuffer.Bytes()
h := sha256.New()
h.Write(layerTarBlob)
hashStr := hex.EncodeToString(h.Sum(nil))
layerHashes = append(layerHashes, hashStr)
err := ioutil.WriteFile(path.Join(destPath, hashStr), layerTarBlob, 0644)
if err != nil {
return nil, err
}
}
return layerHashes, nil
}
func GenDocker22Config(destPath string, conf typesV2.ImageConfig, layerHashes []string) (string, error) {
conf.RootFS = &typesV2.ImageConfigRootFS{}
conf.RootFS.Type = "layers"
for _, h := range layerHashes {
conf.RootFS.DiffIDs = append(conf.RootFS.DiffIDs, "sha256:"+h)
}
confblob, err := json.Marshal(conf)
if err != nil {
return "", err
}
h := sha256.New()
h.Write(confblob)
hashStr := hex.EncodeToString(h.Sum(nil))
err = ioutil.WriteFile(path.Join(destPath, hashStr), confblob, 0644)
if err != nil {
return "", err
}
return hashStr, nil
}
func GenDocker22Manifest(destPath, configHash string, layerHashes []string) error {
getDigestSize := func(digest string) (int64, error) {
fi, err := os.Stat(path.Join(destPath, digest))
if err != nil {
return 0, err
}
return fi.Size(), nil
}
configSize, err := getDigestSize(configHash)
if err != nil {
return err
}
manifest := &typesV2.ImageManifest{
SchemaVersion: 2,
MediaType: common.MediaTypeDockerV22Manifest,
Config: &typesV2.ImageManifestDigest{
MediaType: common.MediaTypeDockerV22Config,
Size: int(configSize),
Digest: "sha256:" + configHash,
},
}
for _, h := range layerHashes {
layerSize, err := getDigestSize(h)
if err != nil {
return err
}
manifest.Layers = append(manifest.Layers,
&typesV2.ImageManifestDigest{
MediaType: common.MediaTypeDockerV22RootFS,
Size: int(layerSize),
Digest: "sha256:" + h,
})
}
manblob, err := json.Marshal(manifest)
if err != nil {
return err
}
err = ioutil.WriteFile(path.Join(destPath, "manifest.json"), manblob, 0644)
if err != nil {
return err
}
return nil
}
|
