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helm/internal/experimental/registry/cache.go

369 lines
10 KiB

/*
Copyright The Helm Authors.
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 registry // import "helm.sh/helm/v3/internal/experimental/registry"
import (
"bytes"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"time"
"github.com/containerd/containerd/content"
"github.com/containerd/containerd/errdefs"
orascontent "github.com/deislabs/oras/pkg/content"
digest "github.com/opencontainers/go-digest"
specs "github.com/opencontainers/image-spec/specs-go"
ocispec "github.com/opencontainers/image-spec/specs-go/v1"
"github.com/pkg/errors"
"helm.sh/helm/v3/pkg/chart"
"helm.sh/helm/v3/pkg/chart/loader"
"helm.sh/helm/v3/pkg/chartutil"
)
const (
// CacheRootDir is the root directory for a cache
CacheRootDir = "cache"
)
type (
// Cache handles local/in-memory storage of Helm charts, compliant with OCI Layout
Cache struct {
debug bool
out io.Writer
rootDir string
ociStore *orascontent.OCIStore
memoryStore *orascontent.Memorystore
}
// CacheRefSummary contains as much info as available describing a chart reference in cache
// Note: fields here are sorted by the order in which they are set in FetchReference method
CacheRefSummary struct {
Name string
Repo string
Tag string
Exists bool
Manifest *ocispec.Descriptor
Config *ocispec.Descriptor
ContentLayer *ocispec.Descriptor
Size int64
Digest digest.Digest
CreatedAt time.Time
Chart *chart.Chart
}
)
// NewCache returns a new OCI Layout-compliant cache with config
func NewCache(opts ...CacheOption) (*Cache, error) {
cache := &Cache{
out: ioutil.Discard,
}
for _, opt := range opts {
opt(cache)
}
// validate
if cache.rootDir == "" {
return nil, errors.New("must set cache root dir on initialization")
}
return cache, nil
}
// FetchReference retrieves a chart ref from cache
func (cache *Cache) FetchReference(ref *Reference) (*CacheRefSummary, error) {
if err := cache.init(); err != nil {
return nil, err
}
r := CacheRefSummary{
Name: ref.FullName(),
Repo: ref.Repo,
Tag: ref.Tag,
}
for _, desc := range cache.ociStore.ListReferences() {
if desc.Annotations[ocispec.AnnotationRefName] == r.Name {
r.Exists = true
manifestBytes, err := cache.fetchBlob(&desc)
if err != nil {
return &r, err
}
var manifest ocispec.Manifest
err = json.Unmarshal(manifestBytes, &manifest)
if err != nil {
return &r, err
}
r.Manifest = &desc
r.Config = &manifest.Config
numLayers := len(manifest.Layers)
if numLayers != 1 {
return &r, errors.New(
fmt.Sprintf("manifest does not contain exactly 1 layer (total: %d)", numLayers))
}
var contentLayer *ocispec.Descriptor
for _, layer := range manifest.Layers {
switch layer.MediaType {
case HelmChartContentLayerMediaType:
contentLayer = &layer
}
}
if contentLayer == nil {
return &r, errors.New(
fmt.Sprintf("manifest does not contain a layer with mediatype %s", HelmChartContentLayerMediaType))
}
if contentLayer.Size == 0 {
return &r, errors.New(
fmt.Sprintf("manifest layer with mediatype %s is of size 0", HelmChartContentLayerMediaType))
}
r.ContentLayer = contentLayer
info, err := cache.ociStore.Info(ctx(cache.out, cache.debug), contentLayer.Digest)
if err != nil {
return &r, err
}
r.Size = info.Size
r.Digest = info.Digest
r.CreatedAt = info.CreatedAt
contentBytes, err := cache.fetchBlob(contentLayer)
if err != nil {
return &r, err
}
ch, err := loader.LoadArchive(bytes.NewBuffer(contentBytes))
if err != nil {
return &r, err
}
r.Chart = ch
}
}
return &r, nil
}
// StoreReference stores a chart ref in cache
func (cache *Cache) StoreReference(ref *Reference, ch *chart.Chart) (*CacheRefSummary, error) {
if err := cache.init(); err != nil {
return nil, err
}
r := CacheRefSummary{
Name: ref.FullName(),
Repo: ref.Repo,
Tag: ref.Tag,
Chart: ch,
}
existing, _ := cache.FetchReference(ref)
r.Exists = existing.Exists
config, _, err := cache.saveChartConfig(ch)
if err != nil {
return &r, err
}
r.Config = config
contentLayer, _, err := cache.saveChartContentLayer(ch)
if err != nil {
return &r, err
}
r.ContentLayer = contentLayer
info, err := cache.ociStore.Info(ctx(cache.out, cache.debug), contentLayer.Digest)
if err != nil {
return &r, err
}
r.Size = info.Size
r.Digest = info.Digest
r.CreatedAt = info.CreatedAt
manifest, _, err := cache.saveChartManifest(config, contentLayer)
if err != nil {
return &r, err
}
r.Manifest = manifest
return &r, nil
}
// DeleteReference deletes a chart ref from cache
// TODO: garbage collection, only manifest removed
func (cache *Cache) DeleteReference(ref *Reference) (*CacheRefSummary, error) {
if err := cache.init(); err != nil {
return nil, err
}
r, err := cache.FetchReference(ref)
if err != nil || !r.Exists {
return r, err
}
cache.ociStore.DeleteReference(r.Name)
err = cache.ociStore.SaveIndex()
return r, err
}
// ListReferences lists all chart refs in a cache
func (cache *Cache) ListReferences() ([]*CacheRefSummary, error) {
if err := cache.init(); err != nil {
return nil, err
}
var rr []*CacheRefSummary
for _, desc := range cache.ociStore.ListReferences() {
name := desc.Annotations[ocispec.AnnotationRefName]
if name == "" {
if cache.debug {
fmt.Fprintf(cache.out, "warning: found manifest without name: %s", desc.Digest.Hex())
}
continue
}
ref, err := ParseReference(name)
if err != nil {
return rr, err
}
r, err := cache.FetchReference(ref)
if err != nil {
return rr, err
}
rr = append(rr, r)
}
return rr, nil
}
// AddManifest provides a manifest to the cache index.json
func (cache *Cache) AddManifest(ref *Reference, manifest *ocispec.Descriptor) error {
if err := cache.init(); err != nil {
return err
}
cache.ociStore.AddReference(ref.FullName(), *manifest)
err := cache.ociStore.SaveIndex()
return err
}
// Provider provides a valid containerd Provider
func (cache *Cache) Provider() content.Provider {
return content.Provider(cache.ociStore)
}
// Ingester provides a valid containerd Ingester
func (cache *Cache) Ingester() content.Ingester {
return content.Ingester(cache.ociStore)
}
// ProvideIngester provides a valid oras ProvideIngester
func (cache *Cache) ProvideIngester() orascontent.ProvideIngester {
return orascontent.ProvideIngester(cache.ociStore)
}
// init creates files needed necessary for OCI layout store
func (cache *Cache) init() error {
if cache.ociStore == nil {
ociStore, err := orascontent.NewOCIStore(cache.rootDir)
if err != nil {
return err
}
cache.ociStore = ociStore
cache.memoryStore = orascontent.NewMemoryStore()
}
return nil
}
// saveChartConfig stores the Chart.yaml as json blob and returns a descriptor
func (cache *Cache) saveChartConfig(ch *chart.Chart) (*ocispec.Descriptor, bool, error) {
configBytes, err := json.Marshal(ch.Metadata)
if err != nil {
return nil, false, err
}
configExists, err := cache.storeBlob(configBytes)
if err != nil {
return nil, configExists, err
}
descriptor := cache.memoryStore.Add("", HelmChartConfigMediaType, configBytes)
return &descriptor, configExists, nil
}
// saveChartContentLayer stores the chart as tarball blob and returns a descriptor
func (cache *Cache) saveChartContentLayer(ch *chart.Chart) (*ocispec.Descriptor, bool, error) {
destDir := filepath.Join(cache.rootDir, ".build")
os.MkdirAll(destDir, 0755)
tmpFile, err := chartutil.Save(ch, destDir)
defer os.Remove(tmpFile)
if err != nil {
return nil, false, errors.Wrap(err, "failed to save")
}
contentBytes, err := ioutil.ReadFile(tmpFile)
if err != nil {
return nil, false, err
}
contentExists, err := cache.storeBlob(contentBytes)
if err != nil {
return nil, contentExists, err
}
descriptor := cache.memoryStore.Add("", HelmChartContentLayerMediaType, contentBytes)
return &descriptor, contentExists, nil
}
// saveChartManifest stores the chart manifest as json blob and returns a descriptor
func (cache *Cache) saveChartManifest(config *ocispec.Descriptor, contentLayer *ocispec.Descriptor) (*ocispec.Descriptor, bool, error) {
manifest := ocispec.Manifest{
Versioned: specs.Versioned{SchemaVersion: 2},
Config: *config,
Layers: []ocispec.Descriptor{*contentLayer},
}
manifestBytes, err := json.Marshal(manifest)
if err != nil {
return nil, false, err
}
manifestExists, err := cache.storeBlob(manifestBytes)
if err != nil {
return nil, manifestExists, err
}
descriptor := ocispec.Descriptor{
MediaType: ocispec.MediaTypeImageManifest,
Digest: digest.FromBytes(manifestBytes),
Size: int64(len(manifestBytes)),
}
return &descriptor, manifestExists, nil
}
// storeBlob stores a blob on filesystem
func (cache *Cache) storeBlob(blobBytes []byte) (bool, error) {
var exists bool
writer, err := cache.ociStore.Store.Writer(ctx(cache.out, cache.debug),
content.WithRef(digest.FromBytes(blobBytes).Hex()))
if err != nil {
return exists, err
}
_, err = writer.Write(blobBytes)
if err != nil {
return exists, err
}
err = writer.Commit(ctx(cache.out, cache.debug), 0, writer.Digest())
if err != nil {
if !errdefs.IsAlreadyExists(err) {
return exists, err
}
exists = true
}
err = writer.Close()
return exists, err
}
// fetchBlob retrieves a blob from filesystem
func (cache *Cache) fetchBlob(desc *ocispec.Descriptor) ([]byte, error) {
reader, err := cache.ociStore.ReaderAt(ctx(cache.out, cache.debug), *desc)
if err != nil {
return nil, err
}
defer reader.Close()
bytes := make([]byte, desc.Size)
_, err = reader.ReadAt(bytes, 0)
if err != nil {
return nil, err
}
return bytes, nil
}