policystatemetrics: use observer.GetSensorManager()

policystatemetrics needs a reference to the sensor manager so that it
can collect metrics. Currently, this reference is passed using
observer.GetSensorManager() at initialization time.

In observer tests, we currently do not restart the metrics (see [1])
which means that if we create a new observer, then the metrics will
still reference the old sensor manager.

Fix this by having policystatemetrics to call
observer.GetSensorManager() to get the latest version of the sensor
manager.

[1] https://github.com/cilium/tetragon/blob/22eb995b19207ac0ced2dd83950ec8e8aedd122d/pkg/observer/observertesthelper/observer_test_helper.go#L272-L276

Signed-off-by: Kornilios Kourtis <kornilios@isovalent.com>

pkg/metrics/policystatemetrics/policystatemetrics.go

@@ -11,17 +11,15 @@ import (
 	"github.com/cilium/tetragon/pkg/logger"
 	"github.com/cilium/tetragon/pkg/metrics/consts"
 	"github.com/cilium/tetragon/pkg/observer"
-	"github.com/cilium/tetragon/pkg/sensors"
 	"github.com/prometheus/client_golang/prometheus"
 )
 
 type policyStateCollector struct {
-	descriptor    *prometheus.Desc
-	sensorManager *sensors.Manager
+	descriptor *prometheus.Desc
 }
 
 func InitMetrics(registry *prometheus.Registry) {
-	registry.MustRegister(newPolicyStateCollector(observer.GetSensorManager()))
+	registry.MustRegister(newPolicyStateCollector())
 }
 
 func InitMetricsForDocs(registry *prometheus.Registry) {
@@ -30,14 +28,13 @@ func InitMetricsForDocs(registry *prometheus.Registry) {
 
 // This metric collector converts the output of ListTracingPolicies into a few
 // gauges metrics on collection. Thus, it needs a sensor manager to query.
-func newPolicyStateCollector(sensorManager *sensors.Manager) *policyStateCollector {
+func newPolicyStateCollector() *policyStateCollector {
 	return &policyStateCollector{
 		descriptor: prometheus.NewDesc(
 			prometheus.BuildFQName(consts.MetricsNamespace, "", "tracingpolicy_loaded"),
 			"The number of loaded tracing policy by state.",
 			[]string{"state"}, nil,
 		),
-		sensorManager: sensorManager,
 	}
 }
 
@@ -46,11 +43,13 @@ func (c *policyStateCollector) Describe(ch chan<- *prometheus.Desc) {
 }
 
 func (c *policyStateCollector) Collect(ch chan<- prometheus.Metric) {
-	if c.sensorManager == nil {
+
+	sm := observer.GetSensorManager()
+	if sm == nil {
 		logger.GetLogger().Debug("failed retrieving the sensor manager: manager is nil")
 		return
 	}
-	list, err := c.sensorManager.ListTracingPolicies(context.Background())
+	list, err := sm.ListTracingPolicies(context.Background())
 	if err != nil {
 		logger.GetLogger().WithError(err).Warn("error listing tracing policies to collect policies state")
 		return
@@ -97,7 +96,7 @@ type policyStateZeroCollector struct {
 
 func newPolicyStateZeroCollector() prometheus.Collector {
 	return &policyStateZeroCollector{
-		policyStateCollector: *newPolicyStateCollector(nil),
+		policyStateCollector: *newPolicyStateCollector(),
 	}
 }
 

pkg/metrics/policystatemetrics/policystatemetrics_test.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/cilium/tetragon/pkg/observer"
 	tus "github.com/cilium/tetragon/pkg/testutils/sensors"
 	"github.com/cilium/tetragon/pkg/tracingpolicy"
 	"github.com/prometheus/client_golang/prometheus"
@@ -30,9 +31,16 @@ tetragon_tracingpolicy_loaded{state="load_error"} %d
 	}
 
 	reg := prometheus.NewRegistry()
+
+	// NB(kkourt): the policy state collector uses observer.GetSensorManager() to get the sensor
+	// manager because in the observer tests we only initialize metrics while the observer
+	// changes for every test (see:
+	// https://github.com/cilium/tetragon/blob/22eb995b19207ac0ced2dd83950ec8e8aedd122d/pkg/observer/observertesthelper/observer_test_helper.go#L272-L276)
 	manager := tus.GetTestSensorManager(context.TODO(), t).Manager
+	observer.SetSensorManager(manager)
+	t.Cleanup(observer.ResetSensorManager)
 
-	collector := newPolicyStateCollector(manager)
+	collector := newPolicyStateCollector()
 	reg.Register(collector)
 
 	err := manager.AddTracingPolicy(context.TODO(), &tracingpolicy.GenericTracingPolicy{