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523 lines
15 KiB
Go
523 lines
15 KiB
Go
// SPDX-License-Identifier: AGPL-3.0-only
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// Provenance-includes-location: https://github.com/kubernetes-sigs/apiserver-runtime/blob/main/pkg/experimental/storage/filepath/jsonfile_rest.go
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// Provenance-includes-license: Apache-2.0
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// Provenance-includes-copyright: The Kubernetes Authors.
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package file
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import (
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"context"
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"errors"
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"fmt"
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"path/filepath"
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"reflect"
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"strings"
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"time"
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"github.com/bwmarrin/snowflake"
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apierrors "k8s.io/apimachinery/pkg/api/errors"
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"k8s.io/apimachinery/pkg/api/meta"
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"k8s.io/apimachinery/pkg/conversion"
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"k8s.io/apimachinery/pkg/runtime"
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"k8s.io/apimachinery/pkg/runtime/schema"
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"k8s.io/apimachinery/pkg/watch"
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"k8s.io/apiserver/pkg/storage"
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"k8s.io/apiserver/pkg/storage/storagebackend"
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"k8s.io/apiserver/pkg/storage/storagebackend/factory"
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"k8s.io/client-go/tools/cache"
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)
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const MaxUpdateAttempts = 30
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var _ storage.Interface = (*Storage)(nil)
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// Replace with: https://github.com/kubernetes/kubernetes/blob/v1.29.0-alpha.3/staging/src/k8s.io/apiserver/pkg/storage/errors.go#L28
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// When we upgrade to 1.29
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var errResourceVersionSetOnCreate = errors.New("resourceVersion should not be set on objects to be created")
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// Storage implements storage.Interface and storage resources as JSON files on disk.
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type Storage struct {
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root string
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gr schema.GroupResource
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codec runtime.Codec
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keyFunc func(obj runtime.Object) (string, error)
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newFunc func() runtime.Object
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newListFunc func() runtime.Object
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getAttrsFunc storage.AttrFunc
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trigger storage.IndexerFuncs
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indexers *cache.Indexers
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watchSet *WatchSet
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}
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// ErrFileNotExists means the file doesn't actually exist.
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var ErrFileNotExists = fmt.Errorf("file doesn't exist")
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// ErrNamespaceNotExists means the directory for the namespace doesn't actually exist.
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var ErrNamespaceNotExists = errors.New("namespace does not exist")
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func getResourceVersion() (*uint64, error) {
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node, err := snowflake.NewNode(1)
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if err != nil {
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return nil, err
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}
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snowflakeNumber := node.Generate().Int64()
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resourceVersion := uint64(snowflakeNumber)
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return &resourceVersion, nil
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}
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// NewStorage instantiates a new Storage.
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func NewStorage(
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config *storagebackend.ConfigForResource,
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resourcePrefix string,
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keyFunc func(obj runtime.Object) (string, error),
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newFunc func() runtime.Object,
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newListFunc func() runtime.Object,
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getAttrsFunc storage.AttrFunc,
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trigger storage.IndexerFuncs,
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indexers *cache.Indexers,
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) (storage.Interface, factory.DestroyFunc, error) {
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if err := ensureDir(resourcePrefix); err != nil {
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return nil, func() {}, fmt.Errorf("could not establish a writable directory at path=%s", resourcePrefix)
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}
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ws := NewWatchSet()
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return &Storage{
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root: resourcePrefix,
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gr: config.GroupResource,
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codec: config.Codec,
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keyFunc: keyFunc,
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newFunc: newFunc,
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newListFunc: newListFunc,
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getAttrsFunc: getAttrsFunc,
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trigger: trigger,
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indexers: indexers,
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watchSet: ws,
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}, func() {
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ws.cleanupWatchers()
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}, nil
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}
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// Returns Versioner associated with this storage.
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func (s *Storage) Versioner() storage.Versioner {
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return &storage.APIObjectVersioner{}
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}
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// Create adds a new object at a key unless it already exists. 'ttl' is time-to-live
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// in seconds (0 means forever). If no error is returned and out is not nil, out will be
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// set to the read value from database.
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func (s *Storage) Create(ctx context.Context, key string, obj runtime.Object, out runtime.Object, ttl uint64) error {
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filename := s.filePath(key)
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if exists(filename) {
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return storage.NewKeyExistsError(key, 0)
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}
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dirname := filepath.Dir(filename)
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if err := ensureDir(dirname); err != nil {
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return err
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}
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generatedRV, err := getResourceVersion()
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if err != nil {
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return err
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}
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metaObj, err := meta.Accessor(obj)
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if err != nil {
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return err
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}
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metaObj.SetSelfLink("")
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if metaObj.GetResourceVersion() != "" {
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return errResourceVersionSetOnCreate
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}
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if err := s.Versioner().UpdateObject(obj, *generatedRV); err != nil {
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return err
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}
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if err := writeFile(s.codec, filename, obj); err != nil {
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return err
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}
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// set a timer to delete the file after ttl seconds
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if ttl > 0 {
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time.AfterFunc(time.Second*time.Duration(ttl), func() {
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if err := s.Delete(ctx, key, s.newFunc(), &storage.Preconditions{}, func(ctx context.Context, obj runtime.Object) error { return nil }, obj); err != nil {
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panic(err)
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}
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})
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}
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if err := s.Get(ctx, key, storage.GetOptions{}, out); err != nil {
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return err
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}
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s.watchSet.notifyWatchers(watch.Event{
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Object: out.DeepCopyObject(),
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Type: watch.Added,
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})
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return nil
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}
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// Delete removes the specified key and returns the value that existed at that spot.
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// If key didn't exist, it will return NotFound storage error.
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// If 'cachedExistingObject' is non-nil, it can be used as a suggestion about the
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// current version of the object to avoid read operation from storage to get it.
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// However, the implementations have to retry in case suggestion is stale.
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func (s *Storage) Delete(
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ctx context.Context,
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key string,
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out runtime.Object,
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preconditions *storage.Preconditions,
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validateDeletion storage.ValidateObjectFunc,
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cachedExistingObject runtime.Object,
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) error {
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filename := s.filePath(key)
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var currentState runtime.Object
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var stateIsCurrent bool
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if cachedExistingObject != nil {
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currentState = cachedExistingObject
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} else {
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getOptions := storage.GetOptions{}
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if preconditions != nil && preconditions.ResourceVersion != nil {
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getOptions.ResourceVersion = *preconditions.ResourceVersion
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}
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if err := s.Get(ctx, key, getOptions, currentState); err == nil {
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stateIsCurrent = true
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}
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}
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for {
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if preconditions != nil {
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if err := preconditions.Check(key, out); err != nil {
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if stateIsCurrent {
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return err
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}
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// If the state is not current, we need to re-read the state and try again.
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if err := s.Get(ctx, key, storage.GetOptions{}, currentState); err != nil {
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return err
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}
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stateIsCurrent = true
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continue
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}
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}
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if err := validateDeletion(ctx, out); err != nil {
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if stateIsCurrent {
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return err
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}
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// If the state is not current, we need to re-read the state and try again.
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if err := s.Get(ctx, key, storage.GetOptions{}, currentState); err == nil {
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stateIsCurrent = true
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}
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continue
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}
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if err := s.Get(ctx, key, storage.GetOptions{}, out); err != nil {
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return err
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}
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generatedRV, err := getResourceVersion()
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if err != nil {
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return err
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}
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if err := s.Versioner().UpdateObject(out, *generatedRV); err != nil {
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return err
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}
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if err := deleteFile(filename); err != nil {
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return err
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}
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s.watchSet.notifyWatchers(watch.Event{
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Object: out.DeepCopyObject(),
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Type: watch.Deleted,
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})
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return nil
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}
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}
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// Watch begins watching the specified key. Events are decoded into API objects,
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// and any items selected by 'p' are sent down to returned watch.Interface.
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// resourceVersion may be used to specify what version to begin watching,
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// which should be the current resourceVersion, and no longer rv+1
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// (e.g. reconnecting without missing any updates).
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// If resource version is "0", this interface will get current object at given key
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// and send it in an "ADDED" event, before watch starts.
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func (s *Storage) Watch(ctx context.Context, key string, opts storage.ListOptions) (watch.Interface, error) {
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p := opts.Predicate
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jw := s.watchSet.newWatch()
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listObj := s.newListFunc()
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if opts.ResourceVersion == "0" {
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err := s.GetList(ctx, key, opts, listObj)
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if err != nil {
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return nil, err
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}
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}
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initEvents := make([]watch.Event, 0)
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listPtr, err := meta.GetItemsPtr(listObj)
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if err != nil {
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return nil, err
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}
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v, err := conversion.EnforcePtr(listPtr)
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if err != nil {
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return nil, err
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}
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if v.IsNil() {
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jw.Start(p, initEvents)
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return jw, nil
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}
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for _, obj := range v.Elem().Interface().([]runtime.Object) {
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initEvents = append(initEvents, watch.Event{
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Type: watch.Added,
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Object: obj.DeepCopyObject(),
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})
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}
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jw.Start(p, initEvents)
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return jw, nil
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}
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// Get unmarshals object found at key into objPtr. On a not found error, will either
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// return a zero object of the requested type, or an error, depending on 'opts.ignoreNotFound'.
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// Treats empty responses and nil response nodes exactly like a not found error.
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// The returned contents may be delayed, but it is guaranteed that they will
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// match 'opts.ResourceVersion' according 'opts.ResourceVersionMatch'.
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func (s *Storage) Get(ctx context.Context, key string, opts storage.GetOptions, objPtr runtime.Object) error {
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filename := s.filePath(key)
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obj, err := readFile(s.codec, filename, func() runtime.Object {
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return objPtr
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})
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if err != nil {
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if opts.IgnoreNotFound {
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return runtime.SetZeroValue(objPtr)
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}
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rv, err := s.Versioner().ParseResourceVersion(opts.ResourceVersion)
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if err != nil {
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return err
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}
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return storage.NewKeyNotFoundError(key, int64(rv))
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}
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currentVersion, err := s.Versioner().ObjectResourceVersion(obj)
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if err != nil {
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return err
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}
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if err = s.validateMinimumResourceVersion(opts.ResourceVersion, currentVersion); err != nil {
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return err
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}
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return nil
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}
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// GetList unmarshalls objects found at key into a *List api object (an object
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// that satisfies runtime.IsList definition).
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// If 'opts.Recursive' is false, 'key' is used as an exact match. If `opts.Recursive'
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// is true, 'key' is used as a prefix.
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// The returned contents may be delayed, but it is guaranteed that they will
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// match 'opts.ResourceVersion' according 'opts.ResourceVersionMatch'.
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func (s *Storage) GetList(ctx context.Context, key string, opts storage.ListOptions, listObj runtime.Object) error {
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generatedRV, err := getResourceVersion()
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if err != nil {
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return err
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}
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remainingItems := int64(0)
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if err := s.Versioner().UpdateList(listObj, *generatedRV, "", &remainingItems); err != nil {
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return err
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}
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if opts.ResourceVersion != "" {
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resourceVersionInt, err := s.Versioner().ParseResourceVersion(opts.ResourceVersion)
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if err != nil {
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return err
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}
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if err := s.Versioner().UpdateList(listObj, resourceVersionInt, "", &remainingItems); err != nil {
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return err
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}
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}
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objs, err := readDirRecursive(s.codec, key, s.newFunc)
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if err != nil {
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return err
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}
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listPtr, err := meta.GetItemsPtr(listObj)
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if err != nil {
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return err
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}
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v, err := conversion.EnforcePtr(listPtr)
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if err != nil {
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return err
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}
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for _, obj := range objs {
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currentVersion, err := s.Versioner().ObjectResourceVersion(obj)
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if err != nil {
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return err
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}
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if err = s.validateMinimumResourceVersion(opts.ResourceVersion, currentVersion); err != nil {
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continue
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}
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ok, err := opts.Predicate.Matches(obj)
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if err == nil && ok {
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v.Set(reflect.Append(v, reflect.ValueOf(obj).Elem()))
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}
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}
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return nil
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}
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// GuaranteedUpdate keeps calling 'tryUpdate()' to update key 'key' (of type 'destination')
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// retrying the update until success if there is index conflict.
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// Note that object passed to tryUpdate may change across invocations of tryUpdate() if
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// other writers are simultaneously updating it, so tryUpdate() needs to take into account
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// the current contents of the object when deciding how the update object should look.
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// If the key doesn't exist, it will return NotFound storage error if ignoreNotFound=false
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// else `destination` will be set to the zero value of it's type.
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// If the eventual successful invocation of `tryUpdate` returns an output with the same serialized
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// contents as the input, it won't perform any update, but instead set `destination` to an object with those
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// contents.
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// If 'cachedExistingObject' is non-nil, it can be used as a suggestion about the
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// current version of the object to avoid read operation from storage to get it.
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// However, the implementations have to retry in case suggestion is stale.
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func (s *Storage) GuaranteedUpdate(
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ctx context.Context,
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key string,
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destination runtime.Object,
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ignoreNotFound bool,
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preconditions *storage.Preconditions,
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tryUpdate storage.UpdateFunc,
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cachedExistingObject runtime.Object,
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) error {
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var res storage.ResponseMeta
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for attempt := 1; attempt <= MaxUpdateAttempts; attempt = attempt + 1 {
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var (
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filename = s.filePath(key)
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obj runtime.Object
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err error
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created bool
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)
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if !exists(filename) && !ignoreNotFound {
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return apierrors.NewNotFound(s.gr, s.nameFromKey(key))
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}
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obj, err = readFile(s.codec, filename, s.newFunc)
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if err != nil {
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// fallback to new object if the file is not found
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obj = s.newFunc()
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created = true
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}
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if err := preconditions.Check(key, obj); err != nil {
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if attempt >= MaxUpdateAttempts {
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return fmt.Errorf("precondition failed: %w", err)
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}
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continue
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}
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updatedObj, _, err := tryUpdate(obj, res)
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if err != nil {
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if attempt >= MaxUpdateAttempts {
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return err
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}
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continue
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}
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unchanged, err := isUnchanged(s.codec, obj, updatedObj)
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if err != nil {
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return err
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}
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if unchanged {
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u, err := conversion.EnforcePtr(updatedObj)
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if err != nil {
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return fmt.Errorf("unable to enforce updated object pointer: %w", err)
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}
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d, err := conversion.EnforcePtr(destination)
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if err != nil {
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return fmt.Errorf("unable to enforce destination pointer: %w", err)
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}
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d.Set(u)
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return nil
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}
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generatedRV, err := getResourceVersion()
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if err != nil {
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return err
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}
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if err := s.Versioner().UpdateObject(updatedObj, *generatedRV); err != nil {
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return err
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}
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if err := writeFile(s.codec, filename, updatedObj); err != nil {
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return err
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}
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eventType := watch.Modified
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if created {
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eventType = watch.Added
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}
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s.watchSet.notifyWatchers(watch.Event{
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Object: updatedObj.DeepCopyObject(),
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Type: eventType,
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})
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}
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return nil
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}
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// Count returns number of different entries under the key (generally being path prefix).
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func (s *Storage) Count(key string) (int64, error) {
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return 0, nil
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}
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// RequestWatchProgress requests the a watch stream progress status be sent in the
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// watch response stream as soon as possible.
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// Used for monitor watch progress even if watching resources with no changes.
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//
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// If watch is lagging, progress status might:
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// * be pointing to stale resource version. Use etcd KV request to get linearizable resource version.
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// * not be delivered at all. It's recommended to poll request progress periodically.
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//
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// Note: Only watches with matching context grpc metadata will be notified.
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// https://github.com/kubernetes/kubernetes/blob/9325a57125e8502941d1b0c7379c4bb80a678d5c/vendor/go.etcd.io/etcd/client/v3/watch.go#L1037-L1042
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//
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// TODO: Remove when storage.Interface will be separate from etc3.store.
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// Deprecated: Added temporarily to simplify exposing RequestProgress for watch cache.
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func (s *Storage) RequestWatchProgress(ctx context.Context) error {
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return nil
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}
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// validateMinimumResourceVersion returns a 'too large resource' version error when the provided minimumResourceVersion is
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// greater than the most recent actualRevision available from storage.
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func (s *Storage) validateMinimumResourceVersion(minimumResourceVersion string, actualRevision uint64) error {
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if minimumResourceVersion == "" {
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return nil
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}
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minimumRV, err := s.Versioner().ParseResourceVersion(minimumResourceVersion)
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if err != nil {
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return apierrors.NewBadRequest(fmt.Sprintf("invalid resource version: %v", err))
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}
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// Enforce the storage.Interface guarantee that the resource version of the returned data
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// "will be at least 'resourceVersion'".
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if minimumRV > actualRevision {
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return storage.NewTooLargeResourceVersionError(minimumRV, actualRevision, 0)
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}
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return nil
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}
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func (s *Storage) nameFromKey(key string) string {
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return strings.Replace(key, s.root+"/", "", 1)
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}
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