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feat: add LRU validation cache with OpenTelemetry metrics #1936

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bcf8d3a
test: add LRU cache unit and integration tests (TDD Red)
nissessenap Feb 16, 2026
ccd8e3b
feat: implement LRU+TTL cache for validation results
nissessenap Feb 16, 2026
481f870
feat: add opt-in CLI flags to enable validation result cache
nissessenap Feb 16, 2026
8013c95
fix: defensive copy in cache Set, update copyright, extract test helper
nissessenap Feb 16, 2026
2d1dd26
feat: add cache hit/miss debug logging and e2e test resources
nissessenap Feb 16, 2026
03c8dfe
intial reserach metrics
nissessenap Feb 16, 2026
e027623
chore(deps): bump knative.dev/pkg to latest for OTEL metrics
nissessenap Feb 16, 2026
cd4a38d
make reserach decent....
nissessenap Feb 16, 2026
6349c2e
plan
nissessenap Feb 16, 2026
8fbc75d
update plan
nissessenap Feb 16, 2026
6a3a629
feat: add OpenTelemetry cache metrics for LRU validation cache
nissessenap Feb 16, 2026
34f5e68
refactor: move gauge registration to LRUCache instance to prevent cal…
nissessenap Feb 16, 2026
08e88b6
refactor: move registerEntriesGauge to metrics.go for cohesion
nissessenap Feb 17, 2026
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15 changes: 15 additions & 0 deletions cmd/webhook/main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -103,6 +103,12 @@ var (
// trustrootResyncPeriod holds the interval which the TrustRoot will resync
// This is essential for triggering a reconcile update for potentially stale TUF metadata.
trustrootResyncPeriod = flag.Duration("trustroot-resync-period", 24*time.Hour, "The resync period for ClusterImagePolicies. The default is 24h.")

// Cache configuration for validating webhook results.
// https://github.com/sigstore/policy-controller/issues/647
enableCache = flag.Bool("enable-cache", false, "Enable in-memory LRU cache for validation results.")
cacheSize = flag.Int("cache-size", 1024, "Maximum number of entries in the validation result cache.")
cacheTTL = flag.Duration("cache-ttl", 1*time.Hour, "TTL for cached validation results.")
)

func main() {
Expand Down Expand Up @@ -238,6 +244,12 @@ func NewValidatingAdmissionController(ctx context.Context, cmw configmap.Watcher
kc := kubeclient.Get(ctx)
validator := cwebhook.NewValidator(ctx)

var cache cwebhook.ResultCache
if *enableCache {
cache = cwebhook.NewLRUCache(*cacheSize, *cacheTTL)
logging.FromContext(ctx).Infof("Validation result cache enabled: size=%d, ttl=%v", *cacheSize, *cacheTTL)
}

return validation.NewAdmissionController(ctx,
// Name of the resource webhook.
*webhookName,
Expand All @@ -253,6 +265,9 @@ func NewValidatingAdmissionController(ctx context.Context, cmw configmap.Watcher
ctx = context.WithValue(ctx, kubeclient.Key{}, kc)
ctx = store.ToContext(ctx)
ctx = policyControllerConfigStore.ToContext(ctx)
if cache != nil {
ctx = cwebhook.ToContext(ctx, cache)
}
ctx = policyduckv1beta1.WithPodScalableValidator(ctx, validator.ValidatePodScalable)
ctx = duckv1.WithPodValidator(ctx, validator.ValidatePod)
ctx = duckv1.WithPodSpecValidator(ctx, validator.ValidatePodSpecable)
Expand Down
146 changes: 72 additions & 74 deletions go.mod
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,6 @@ go 1.25.0
require (
github.com/aws/aws-sdk-go v1.55.6
github.com/aws/aws-sdk-go-v2 v1.36.3 // indirect
github.com/golang/protobuf v1.5.4 // indirect
github.com/golang/snappy v0.0.4 // indirect
github.com/google/go-cmp v0.7.0
github.com/google/go-containerregistry v0.20.3
Expand All @@ -29,28 +28,28 @@ require (
github.com/sigstore/cosign/v2 v2.5.0
github.com/sigstore/rekor v1.3.10
github.com/sigstore/sigstore v1.9.4
github.com/stretchr/testify v1.10.0
github.com/stretchr/testify v1.11.1
github.com/theupdateframework/go-tuf v0.7.0
github.com/titanous/rocacheck v0.0.0-20171023193734-afe73141d399
go.uber.org/zap v1.27.0
golang.org/x/crypto v0.45.0
golang.org/x/net v0.47.0
golang.org/x/sys v0.38.0 // indirect
go.uber.org/zap v1.27.1
golang.org/x/crypto v0.47.0
golang.org/x/net v0.49.0
golang.org/x/sys v0.40.0 // indirect
golang.org/x/time v0.11.0
google.golang.org/grpc v1.71.1 // indirect
google.golang.org/protobuf v1.36.6
google.golang.org/grpc v1.77.0 // indirect
google.golang.org/protobuf v1.36.10
gopkg.in/yaml.v3 v3.0.1
k8s.io/api v0.32.3
k8s.io/apimachinery v0.32.3
k8s.io/client-go v0.32.3
k8s.io/code-generator v0.32.2
k8s.io/kube-openapi v0.0.0-20241105132330-32ad38e42d3f
knative.dev/hack v0.0.0-20240111013919-e89096d74d85
k8s.io/api v0.35.0
k8s.io/apimachinery v0.35.0
k8s.io/client-go v0.35.0
k8s.io/code-generator v0.35.0
k8s.io/kube-openapi v0.0.0-20250910181357-589584f1c912
knative.dev/hack v0.0.0-20260212092700-0126b283bf20
sigs.k8s.io/release-utils v0.11.1
sigs.k8s.io/yaml v1.4.0
sigs.k8s.io/yaml v1.6.0
)

require github.com/spf13/cobra v1.9.1
require github.com/spf13/cobra v1.10.0

require (
github.com/Azure/azure-sdk-for-go v68.0.0+incompatible
Expand All @@ -61,7 +60,8 @@ require (
github.com/docker/docker v28.1.1+incompatible
github.com/docker/docker-credential-helpers v0.9.3
github.com/docker/go-connections v0.5.0
github.com/go-jose/go-jose/v4 v4.1.0
github.com/go-jose/go-jose/v4 v4.1.3
github.com/hashicorp/golang-lru/v2 v2.0.7
github.com/sigstore/protobuf-specs v0.4.1
github.com/sigstore/scaffolding v0.7.22
github.com/sigstore/sigstore-go v0.7.2
Expand All @@ -70,20 +70,21 @@ require (
github.com/sigstore/sigstore/pkg/signature/kms/gcp v1.9.4
github.com/sigstore/sigstore/pkg/signature/kms/hashivault v1.9.4
github.com/spf13/viper v1.20.1
go.opentelemetry.io/otel v1.39.0
go.opentelemetry.io/otel/metric v1.39.0
go.opentelemetry.io/otel/sdk/metric v1.39.0
knative.dev/hack/schema v0.0.0-20240607132042-09143140a254
knative.dev/pkg v0.0.0-20230612155445-74c4be5e935e
knative.dev/pkg v0.0.0-20260213150858-6758a9ff4767
)

require (
cloud.google.com/go v0.120.0 // indirect
cloud.google.com/go/auth v0.16.0 // indirect
cloud.google.com/go/auth/oauth2adapt v0.2.8 // indirect
cloud.google.com/go/compute/metadata v0.6.0 // indirect
cloud.google.com/go/compute/metadata v0.9.0 // indirect
cloud.google.com/go/iam v1.5.0 // indirect
cloud.google.com/go/kms v1.21.2 // indirect
cloud.google.com/go/longrunning v0.6.6 // indirect
contrib.go.opencensus.io/exporter/ocagent v0.7.1-0.20200907061046-05415f1de66d // indirect
contrib.go.opencensus.io/exporter/prometheus v0.4.2 // indirect
cuelang.org/go v0.12.1 // indirect
github.com/AliyunContainerService/ack-ram-tool/pkg/credentials/provider v0.14.0 // indirect
github.com/Azure/azure-sdk-for-go/sdk/internal v1.11.1 // indirect
Expand Down Expand Up @@ -133,7 +134,7 @@ require (
github.com/blang/semver v3.5.1+incompatible // indirect
github.com/blang/semver/v4 v4.0.0 // indirect
github.com/blendle/zapdriver v1.3.1 // indirect
github.com/census-instrumentation/opencensus-proto v0.4.1 // indirect
github.com/cenkalti/backoff/v5 v5.0.3 // indirect
github.com/cespare/xxhash/v2 v2.3.0 // indirect
github.com/chrismellard/docker-credential-acr-env v0.0.0-20230304212654-82a0ddb27589 // indirect
github.com/clbanning/mxj/v2 v2.7.0 // indirect
Expand All @@ -151,18 +152,16 @@ require (
github.com/docker/distribution v2.8.3+incompatible // indirect
github.com/docker/go-units v0.5.0 // indirect
github.com/dustin/go-humanize v1.0.1 // indirect
github.com/emicklei/go-restful/v3 v3.11.0 // indirect
github.com/evanphx/json-patch v5.6.0+incompatible // indirect
github.com/evanphx/json-patch/v5 v5.7.0 // indirect
github.com/emicklei/go-restful/v3 v3.12.2 // indirect
github.com/evanphx/json-patch/v5 v5.9.11 // indirect
github.com/felixge/httpsnoop v1.0.4 // indirect
github.com/fsnotify/fsnotify v1.8.0 // indirect
github.com/fxamacker/cbor/v2 v2.7.0 // indirect
github.com/fsnotify/fsnotify v1.9.0 // indirect
github.com/fxamacker/cbor/v2 v2.9.0 // indirect
github.com/go-chi/chi v4.1.2+incompatible // indirect
github.com/go-ini/ini v1.67.0 // indirect
github.com/go-kit/log v0.2.1 // indirect
github.com/go-logfmt/logfmt v0.5.1 // indirect
github.com/go-logr/logr v1.4.2 // indirect
github.com/go-logr/logr v1.4.3 // indirect
github.com/go-logr/stdr v1.2.2 // indirect
github.com/go-logr/zapr v1.3.0 // indirect
github.com/go-openapi/analysis v0.23.0 // indirect
github.com/go-openapi/errors v0.22.1 // indirect
github.com/go-openapi/jsonpointer v0.21.0 // indirect
Expand All @@ -174,23 +173,21 @@ require (
github.com/go-openapi/swag v0.23.1 // indirect
github.com/go-openapi/validate v0.24.0 // indirect
github.com/go-viper/mapstructure/v2 v2.4.0 // indirect
github.com/gobuffalo/flect v1.0.2 // indirect
github.com/gobuffalo/flect v1.0.3 // indirect
github.com/gobwas/glob v0.2.3 // indirect
github.com/gogo/protobuf v1.3.2 // indirect
github.com/golang-jwt/jwt/v4 v4.5.2 // indirect
github.com/golang-jwt/jwt/v5 v5.2.2 // indirect
github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
github.com/golang-jwt/jwt/v5 v5.3.0 // indirect
github.com/google/certificate-transparency-go v1.3.1 // indirect
github.com/google/gnostic-models v0.6.9-0.20230804172637-c7be7c783f49 // indirect
github.com/google/gnostic-models v0.7.0 // indirect
github.com/google/go-github/v55 v55.0.0 // indirect
github.com/google/go-querystring v1.1.0 // indirect
github.com/google/gofuzz v1.2.0 // indirect
github.com/google/s2a-go v0.1.9 // indirect
github.com/google/uuid v1.6.0 // indirect
github.com/googleapis/enterprise-certificate-proxy v0.3.6 // indirect
github.com/googleapis/gax-go/v2 v2.14.1 // indirect
github.com/gorilla/mux v1.8.1 // indirect
github.com/grpc-ecosystem/grpc-gateway/v2 v2.26.1 // indirect
github.com/grpc-ecosystem/grpc-gateway/v2 v2.27.3 // indirect
github.com/hashicorp/vault/api v1.16.0 // indirect
github.com/in-toto/attestation v1.1.1 // indirect
github.com/in-toto/in-toto-golang v0.9.0 // indirect
Expand All @@ -206,7 +203,7 @@ require (
github.com/moby/docker-image-spec v1.3.1 // indirect
github.com/moby/sys/atomicwriter v0.1.0 // indirect
github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
github.com/modern-go/reflect2 v1.0.2 // indirect
github.com/modern-go/reflect2 v1.0.3-0.20250322232337-35a7c28c31ee // indirect
github.com/mozillazg/docker-credential-acr-helper v0.4.0 // indirect
github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
github.com/nozzle/throttler v0.0.0-20180817012639-2ea982251481 // indirect
Expand All @@ -219,11 +216,11 @@ require (
github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c // indirect
github.com/pkg/errors v0.9.1 // indirect
github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
github.com/prometheus/client_golang v1.21.1 // indirect
github.com/prometheus/client_model v0.6.1 // indirect
github.com/prometheus/common v0.62.0 // indirect
github.com/prometheus/procfs v0.15.1 // indirect
github.com/prometheus/statsd_exporter v0.22.8 // indirect
github.com/prometheus/client_golang v1.23.2 // indirect
github.com/prometheus/client_model v0.6.2 // indirect
github.com/prometheus/common v0.67.4 // indirect
github.com/prometheus/otlptranslator v1.0.0 // indirect
github.com/prometheus/procfs v0.19.2 // indirect
github.com/rcrowley/go-metrics v0.0.0-20201227073835-cf1acfcdf475 // indirect
github.com/sagikazarmark/locafero v0.7.0 // indirect
github.com/sassoftware/relic v7.2.1+incompatible // indirect
Expand All @@ -234,7 +231,7 @@ require (
github.com/sourcegraph/conc v0.3.0 // indirect
github.com/spf13/afero v1.12.0 // indirect
github.com/spf13/cast v1.7.1 // indirect
github.com/spf13/pflag v1.0.6 // indirect
github.com/spf13/pflag v1.0.10 // indirect
github.com/subosito/gotenv v1.6.0 // indirect
github.com/syndtr/goleveldb v1.0.1-0.20220721030215-126854af5e6d // indirect
github.com/tchap/go-patricia/v2 v2.3.2 // indirect
Expand All @@ -249,47 +246,48 @@ require (
github.com/yashtewari/glob-intersection v0.2.0 // indirect
gitlab.com/gitlab-org/api/client-go v0.127.0 // indirect
go.mongodb.org/mongo-driver v1.14.0 // indirect
go.opencensus.io v0.24.0 // indirect
go.opentelemetry.io/auto/sdk v1.1.0 // indirect
go.opentelemetry.io/auto/sdk v1.2.1 // indirect
go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.60.0 // indirect
go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.60.0 // indirect
go.opentelemetry.io/otel v1.35.0 // indirect
go.opentelemetry.io/otel/metric v1.35.0 // indirect
go.opentelemetry.io/otel/sdk v1.35.0 // indirect
go.opentelemetry.io/otel/trace v1.35.0 // indirect
go.uber.org/atomic v1.9.0 // indirect
go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.64.0 // indirect
go.opentelemetry.io/contrib/instrumentation/runtime v0.64.0 // indirect
go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v1.39.0 // indirect
go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp v1.39.0 // indirect
go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.39.0 // indirect
go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.39.0 // indirect
go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.39.0 // indirect
go.opentelemetry.io/otel/exporters/prometheus v0.61.0 // indirect
go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.39.0 // indirect
go.opentelemetry.io/otel/sdk v1.39.0 // indirect
go.opentelemetry.io/otel/trace v1.39.0 // indirect
go.opentelemetry.io/proto/otlp v1.9.0 // indirect
go.uber.org/automaxprocs v1.6.0 // indirect
go.uber.org/multierr v1.11.0 // indirect
golang.org/x/exp v0.0.0-20241108190413-2d47ceb2692f // indirect
golang.org/x/mod v0.29.0 // indirect
golang.org/x/oauth2 v0.29.0 // indirect
golang.org/x/sync v0.18.0 // indirect
golang.org/x/term v0.37.0 // indirect
golang.org/x/text v0.31.0 // indirect
golang.org/x/tools v0.38.0 // indirect
gomodules.xyz/jsonpatch/v2 v2.4.0 // indirect
go.yaml.in/yaml/v2 v2.4.3 // indirect
go.yaml.in/yaml/v3 v3.0.4 // indirect
golang.org/x/exp v0.0.0-20250210185358-939b2ce775ac // indirect
golang.org/x/mod v0.32.0 // indirect
golang.org/x/oauth2 v0.32.0 // indirect
golang.org/x/sync v0.19.0 // indirect
golang.org/x/term v0.39.0 // indirect
golang.org/x/text v0.33.0 // indirect
golang.org/x/tools v0.41.0 // indirect
gomodules.xyz/jsonpatch/v2 v2.5.0 // indirect
google.golang.org/api v0.229.0 // indirect
google.golang.org/genproto v0.0.0-20250303144028-a0af3efb3deb // indirect
google.golang.org/genproto/googleapis/api v0.0.0-20250414145226-207652e42e2e // indirect
google.golang.org/genproto/googleapis/rpc v0.0.0-20250414145226-207652e42e2e // indirect
gopkg.in/evanphx/json-patch.v4 v4.12.0 // indirect
google.golang.org/genproto/googleapis/api v0.0.0-20251202230838-ff82c1b0f217 // indirect
google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217 // indirect
gopkg.in/evanphx/json-patch.v4 v4.13.0 // indirect
gopkg.in/inf.v0 v0.9.1 // indirect
gopkg.in/ini.v1 v1.67.0 // indirect
gopkg.in/yaml.v2 v2.4.0 // indirect
k8s.io/apiextensions-apiserver v0.27.6 // indirect
k8s.io/gengo v0.0.0-20230829151522-9cce18d56c01 // indirect
k8s.io/apiextensions-apiserver v0.35.0 // indirect
k8s.io/gengo/v2 v2.0.0-20250922181213-ec3ebc5fd46b // indirect
k8s.io/klog/v2 v2.130.1 // indirect
k8s.io/utils v0.0.0-20241210054802-24370beab758 // indirect
sigs.k8s.io/json v0.0.0-20241010143419-9aa6b5e7a4b3 // indirect
sigs.k8s.io/structured-merge-diff/v4 v4.4.2 // indirect
k8s.io/utils v0.0.0-20251002143259-bc988d571ff4 // indirect
sigs.k8s.io/json v0.0.0-20250730193827-2d320260d730 // indirect
sigs.k8s.io/randfill v1.0.0 // indirect
sigs.k8s.io/structured-merge-diff/v6 v6.3.0 // indirect
)

// TODO: this dependency causes issues on webhook startup due
// to conflicting "log_dir" flags between this and klog (knative)
replace github.com/golang/glog => github.com/jdolitsky/glog v0.0.0-20220729172235-78744e90d087

replace (
// knative deps require to use an old k8s.io/gengo so we need to replace these ones
k8s.io/code-generator => k8s.io/code-generator v0.29.4
k8s.io/kube-openapi => k8s.io/kube-openapi v0.0.0-20231010175941-2dd684a91f00
)
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