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cri_image_gc.go
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cri_image_gc.go
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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
package runtime
import (
"context"
"errors"
"fmt"
"time"
"github.com/benbjohnson/clock"
"github.com/containerd/containerd"
"github.com/containerd/containerd/images"
"github.com/containerd/containerd/namespaces"
"github.com/containerd/containerd/reference/docker"
"github.com/cosi-project/runtime/pkg/controller"
"github.com/cosi-project/runtime/pkg/resource"
"github.com/cosi-project/runtime/pkg/safe"
"github.com/cosi-project/runtime/pkg/state"
"github.com/siderolabs/gen/optional"
"github.com/siderolabs/gen/xslices"
"go.uber.org/zap"
"github.com/siderolabs/talos/pkg/machinery/constants"
"github.com/siderolabs/talos/pkg/machinery/resources/etcd"
"github.com/siderolabs/talos/pkg/machinery/resources/k8s"
"github.com/siderolabs/talos/pkg/machinery/resources/v1alpha1"
)
// ImageCleanupInterval is the interval at which the image GC controller runs.
const ImageCleanupInterval = 15 * time.Minute
// ImageGCGracePeriod is the minimum age of an image before it can be deleted.
const ImageGCGracePeriod = 4 * ImageCleanupInterval
// CRIImageGCController renders manifests based on templates and config/secrets.
type CRIImageGCController struct {
ImageServiceProvider func() (ImageServiceProvider, error)
Clock clock.Clock
imageFirstSeenUnreferenced map[string]time.Time
}
// ImageServiceProvider wraps the containerd image service.
type ImageServiceProvider interface {
ImageService() images.Store
Close() error
}
// Name implements controller.Controller interface.
func (ctrl *CRIImageGCController) Name() string {
return "runtime.CRIImageGCController"
}
// Inputs implements controller.Controller interface.
func (ctrl *CRIImageGCController) Inputs() []controller.Input {
return []controller.Input{
{
Namespace: v1alpha1.NamespaceName,
Type: v1alpha1.ServiceType,
ID: optional.Some("cri"),
Kind: controller.InputWeak,
},
{
Namespace: k8s.NamespaceName,
Type: k8s.KubeletSpecType,
ID: optional.Some(k8s.KubeletID),
Kind: controller.InputWeak,
},
{
Namespace: etcd.NamespaceName,
Type: etcd.SpecType,
ID: optional.Some(etcd.SpecID),
Kind: controller.InputWeak,
},
}
}
// Outputs implements controller.Controller interface.
func (ctrl *CRIImageGCController) Outputs() []controller.Output {
return nil
}
func defaultImageServiceProvider() (ImageServiceProvider, error) {
criClient, err := containerd.New(constants.CRIContainerdAddress)
if err != nil {
return nil, fmt.Errorf("error creating CRI containerd client: %w", err)
}
return &containerdImageServiceProvider{
criClient: criClient,
}, nil
}
type containerdImageServiceProvider struct {
criClient *containerd.Client
}
func (s *containerdImageServiceProvider) ImageService() images.Store {
return s.criClient.ImageService()
}
func (s *containerdImageServiceProvider) Close() error {
return s.criClient.Close()
}
// Run implements controller.Controller interface.
//
//nolint:gocyclo,cyclop
func (ctrl *CRIImageGCController) Run(ctx context.Context, r controller.Runtime, logger *zap.Logger) error {
if ctrl.ImageServiceProvider == nil {
ctrl.ImageServiceProvider = defaultImageServiceProvider
}
if ctrl.Clock == nil {
ctrl.Clock = clock.New()
}
if ctrl.imageFirstSeenUnreferenced == nil {
ctrl.imageFirstSeenUnreferenced = map[string]time.Time{}
}
var (
criIsUp bool
expectedImages []string
imageServiceProvider ImageServiceProvider
)
ticker := ctrl.Clock.Ticker(ImageCleanupInterval)
defer ticker.Stop()
defer func() {
if imageServiceProvider != nil {
imageServiceProvider.Close() //nolint:errcheck
}
}()
for {
select {
case <-ctx.Done():
return nil
case <-ticker.C:
if !criIsUp || len(expectedImages) == 0 {
continue
}
if imageServiceProvider == nil {
var err error
imageServiceProvider, err = ctrl.ImageServiceProvider()
if err != nil {
return fmt.Errorf("error creating image service provider: %w", err)
}
}
if err := ctrl.cleanup(ctx, logger, imageServiceProvider.ImageService(), expectedImages); err != nil {
return fmt.Errorf("error running image cleanup: %w", err)
}
case <-r.EventCh():
criService, err := safe.ReaderGet[*v1alpha1.Service](ctx, r, resource.NewMetadata(v1alpha1.NamespaceName, v1alpha1.ServiceType, "cri", resource.VersionUndefined))
if err != nil && !state.IsNotFoundError(err) {
return fmt.Errorf("error getting CRI service: %w", err)
}
criIsUp = criService != nil && criService.TypedSpec().Running && criService.TypedSpec().Healthy
expectedImages = nil
etcdSpec, err := safe.ReaderGet[*etcd.Spec](ctx, r, resource.NewMetadata(etcd.NamespaceName, etcd.SpecType, etcd.SpecID, resource.VersionUndefined))
if err != nil && !state.IsNotFoundError(err) {
return fmt.Errorf("error getting etcd spec: %w", err)
}
if etcdSpec != nil {
expectedImages = append(expectedImages, etcdSpec.TypedSpec().Image)
}
kubeletSpec, err := safe.ReaderGet[*k8s.KubeletSpec](ctx, r, resource.NewMetadata(k8s.NamespaceName, k8s.KubeletSpecType, k8s.KubeletID, resource.VersionUndefined))
if err != nil && !state.IsNotFoundError(err) {
return fmt.Errorf("error getting etcd spec: %w", err)
}
if kubeletSpec != nil {
expectedImages = append(expectedImages, kubeletSpec.TypedSpec().Image)
}
}
r.ResetRestartBackoff()
}
}
//nolint:gocyclo
func buildExpectedImageNames(logger *zap.Logger, actualImages []images.Image, expectedImages []string) (map[string]struct{}, error) {
var parseErrors []error
expectedReferences := xslices.Map(expectedImages, func(ref string) docker.Named {
res, parseErr := docker.ParseNamed(ref)
parseErrors = append(parseErrors, parseErr)
return res
})
if err := errors.Join(parseErrors...); err != nil {
return nil, fmt.Errorf("error parsing expected images: %w", err)
}
expectedImageNames := map[string]struct{}{}
for _, image := range actualImages {
imageRef, err := docker.ParseAnyReference(image.Name)
if err != nil {
logger.Debug("failed to parse image reference", zap.Error(err), zap.String("image", image.Name))
continue
}
digest := image.Target.Digest.String()
switch ref := imageRef.(type) {
case docker.NamedTagged:
for _, expectedRef := range expectedReferences {
if expectedRef.Name() != ref.Name() {
continue
}
if expectedTagged, ok := expectedRef.(docker.Tagged); ok && ref.Tag() == expectedTagged.Tag() {
// this is expected image by tag, inject other forms of the ref
expectedImageNames[digest] = struct{}{}
expectedImageNames[expectedRef.Name()+":"+expectedTagged.Tag()] = struct{}{}
expectedImageNames[expectedRef.Name()+"@"+digest] = struct{}{}
}
}
case docker.Canonical:
for _, expectedRef := range expectedReferences {
if expectedRef.Name() != ref.Name() {
continue
}
if expectedDigested, ok := expectedRef.(docker.Digested); ok && ref.Digest() == expectedDigested.Digest() {
// this is expected image by digest, inject other forms of the ref
expectedImageNames[digest] = struct{}{}
expectedImageNames[expectedRef.Name()+"@"+digest] = struct{}{}
// if the image is also tagged, inject the tagged version of it
if expectedTagged, ok := expectedRef.(docker.Tagged); ok {
expectedImageNames[expectedRef.Name()+":"+expectedTagged.Tag()] = struct{}{}
}
}
}
}
}
return expectedImageNames, nil
}
func (ctrl *CRIImageGCController) cleanup(ctx context.Context, logger *zap.Logger, imageService images.Store, expectedImages []string) error {
logger.Debug("running image cleanup")
ctx = namespaces.WithNamespace(ctx, constants.SystemContainerdNamespace)
actualImages, err := imageService.List(ctx)
if err != nil {
return fmt.Errorf("error listing images: %w", err)
}
// first pass: scan actualImages and expand expectedReferences with other non-canonical refs
expectedImageNames, err := buildExpectedImageNames(logger, actualImages, expectedImages)
if err != nil {
return err
}
// second pass, drop whatever is not expected
for _, image := range actualImages {
_, shouldKeep := expectedImageNames[image.Name]
if shouldKeep {
logger.Debug("image is referenced, skipping garbage collection", zap.String("image", image.Name))
delete(ctrl.imageFirstSeenUnreferenced, image.Name)
continue
}
if _, ok := ctrl.imageFirstSeenUnreferenced[image.Name]; !ok {
ctrl.imageFirstSeenUnreferenced[image.Name] = ctrl.Clock.Now()
}
// calculate image age two ways, and pick the minimum:
// * as CRI reports it, which is the time image got pulled
// * as we see it, this means the image won't be deleted until it reaches the age of ImageGCGracePeriod from the moment it became unreferenced
imageAgeCRI := ctrl.Clock.Since(image.CreatedAt)
imageAgeInternal := ctrl.Clock.Since(ctrl.imageFirstSeenUnreferenced[image.Name])
imageAge := min(imageAgeCRI, imageAgeInternal)
if imageAge < ImageGCGracePeriod {
logger.Debug("skipping image cleanup, as it's below minimum age", zap.String("image", image.Name), zap.Duration("age", imageAge))
continue
}
if err = imageService.Delete(ctx, image.Name); err != nil {
return fmt.Errorf("failed to delete an image %s: %w", image.Name, err)
}
delete(ctrl.imageFirstSeenUnreferenced, image.Name)
logger.Info("deleted an image", zap.String("image", image.Name))
}
return nil
}