metrics: Add map pressure metric for auth map

pkg/auth/authmap.go

@@ -18,6 +18,7 @@ type authMap interface {
 	DeleteIf(predicate func(key authKey, info authInfo) bool) error
 	Get(key authKey) (authInfo, error)
 	All() (map[authKey]authInfo, error)
+	MaxEntries() uint32
 }
 
 type authMapCacher interface {

pkg/auth/authmap_cache.go

@@ -13,20 +13,29 @@ import (
 	"golang.org/x/exp/maps"
 
 	"github.com/cilium/cilium/pkg/lock"
+	"github.com/cilium/cilium/pkg/maps/authmap"
+	"github.com/cilium/cilium/pkg/metrics"
 )
 
 type authMapCache struct {
 	logger            logrus.FieldLogger
 	authmap           authMap
 	cacheEntries      map[authKey]authInfoCache
 	cacheEntriesMutex lock.RWMutex
+	pressureGauge     *metrics.GaugeWithThreshold
 }
 
-func newAuthMapCache(logger logrus.FieldLogger, authmap authMap) *authMapCache {
+func newAuthMapCache(logger logrus.FieldLogger, authMap authMap) *authMapCache {
+	var pressureGauge *metrics.GaugeWithThreshold
+
+	if metrics.BPFMapPressure {
+		pressureGauge = metrics.NewBPFMapPressureGauge(authmap.MapName, 0)
+	}
 	return &authMapCache{
-		logger:       logger,
-		authmap:      authmap,
-		cacheEntries: map[authKey]authInfoCache{},
+		logger:        logger,
+		authmap:       authMap,
+		cacheEntries:  map[authKey]authInfoCache{},
+		pressureGauge: pressureGauge,
 	}
 }
 
@@ -69,6 +78,7 @@ func (r *authMapCache) Update(key authKey, info authInfo) error {
 		authInfo: info,
 		storedAt: time.Now(),
 	}
+	r.updatePressureMetric()
 
 	return nil
 }
@@ -88,10 +98,14 @@ func (r *authMapCache) Delete(key authKey) error {
 	}
 
 	delete(r.cacheEntries, key)
-
+	r.updatePressureMetric()
 	return nil
 }
 
+func (r *authMapCache) MaxEntries() uint32 {
+	return r.authmap.MaxEntries()
+}
+
 func (r *authMapCache) DeleteIf(predicate func(key authKey, info authInfo) bool) error {
 	r.cacheEntriesMutex.Lock()
 	defer r.cacheEntriesMutex.Unlock()
@@ -111,7 +125,7 @@ func (r *authMapCache) DeleteIf(predicate func(key authKey, info authInfo) bool)
 			delete(r.cacheEntries, k)
 		}
 	}
-
+	r.updatePressureMetric()
 	return nil
 }
 
@@ -129,8 +143,16 @@ func (r *authMapCache) restoreCache() error {
 		}
 	}
 
+	r.updatePressureMetric()
 	r.logger.
 		WithField("cached_entries", len(r.cacheEntries)).
 		Debug("Restored entries")
 	return nil
 }
+
+func (r *authMapCache) updatePressureMetric() {
+	if r.pressureGauge == nil {
+		return
+	}
+	r.pressureGauge.Set(float64(len(r.cacheEntries)) / float64(r.authmap.MaxEntries()))
+}

pkg/auth/authmap_writer.go

@@ -105,3 +105,7 @@ func (r *authMapWriter) DeleteIf(predicate func(key authKey, info authInfo) bool
 
 	return nil
 }
+
+func (r *authMapWriter) MaxEntries() uint32 {
+	return r.authMap.MaxEntries()
+}

pkg/auth/manager_test.go

@@ -316,6 +316,10 @@ func (r *fakeAuthMap) Update(key authKey, info authInfo) error {
 	return nil
 }
 
+func (r *fakeAuthMap) MaxEntries() uint32 {
+	return 1 << 8
+}
+
 func assertErrorString(errString string) assert.ErrorAssertionFunc {
 	return func(t assert.TestingT, err error, msgAndArgs ...interface{}) bool {
 		return assert.EqualError(t, err, errString, msgAndArgs)

pkg/maps/authmap/auth_map.go

@@ -35,6 +35,9 @@ type Map interface {
 	// IterateWithCallback iterates through all the keys/values of an auth map,
 	// passing each key/value pair to the cb callback.
 	IterateWithCallback(cb IterateCallback) error
+
+	// MaxEntries returns the maximum number of entries the auth map can hold.
+	MaxEntries() uint32
 }
 
 type authMap struct {
@@ -113,6 +116,10 @@ func (m *authMap) IterateWithCallback(cb IterateCallback) error {
 	)
 }
 
+func (m *authMap) MaxEntries() uint32 {
+	return m.bpfMap.MaxEntries()
+}
+
 // AuthKey implements the bpf.MapKey interface.
 //
 // Must be in sync with struct auth_key in <bpf/lib/common.h>

pkg/maps/authmap/fake/auth_map.go

@@ -47,3 +47,7 @@ func (f fakeAuthMap) IterateWithCallback(cb authmap.IterateCallback) error {
 	}
 	return nil
 }
+
+func (f fakeAuthMap) MaxEntries() uint32 {
+	return 1 << 8
+}