tetragon: Add probemetrics package

Signed-off-by: Jiri Olsa <jolsa@kernel.org>

pkg/metrics/metricsconfig/initmetrics.go

@@ -13,6 +13,7 @@ import (
 	"github.com/cilium/tetragon/pkg/metrics/mapmetrics"
 	"github.com/cilium/tetragon/pkg/metrics/opcodemetrics"
 	"github.com/cilium/tetragon/pkg/metrics/policyfiltermetrics"
+	"github.com/cilium/tetragon/pkg/metrics/probemetrics"
 	"github.com/cilium/tetragon/pkg/metrics/processexecmetrics"
 	"github.com/cilium/tetragon/pkg/metrics/ratelimitmetrics"
 	"github.com/cilium/tetragon/pkg/metrics/ringbufmetrics"
@@ -51,6 +52,7 @@ func InitAllMetrics(registry *prometheus.Registry) {
 		process.NewBPFCollector(),
 	))
 	registry.MustRegister(eventmetrics.NewBPFCollector())
+	registry.MustRegister(probemetrics.NewBPFCollector())
 
 	// register common third-party collectors
 	registry.MustRegister(collectors.NewGoCollector())

pkg/metrics/probemetrics/collector.go

@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright Authors of Tetragon
+
+package probemetrics
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+// bpfCollector implements prometheus.Collector. It collects metrics directly from BPF maps.
+type bpfCollector struct{}
+
+func NewBPFCollector() prometheus.Collector {
+	return &bpfCollector{}
+}
+
+func (c *bpfCollector) Describe(ch chan<- *prometheus.Desc) {
+	ch <- MissedProbes.Desc()
+}
+
+func (c *bpfCollector) Collect(ch chan<- prometheus.Metric) {
+	lock.Lock()
+	defer lock.Unlock()
+
+	for key, stat := range stats {
+		ch <- MissedProbes.MustMetric(stat.missed, stat.policy, key.attach)
+	}
+}

pkg/metrics/probemetrics/probemetrics.go

@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright Authors of Tetragon
+
+package probemetrics
+
+import (
+	"sync"
+
+	"github.com/cilium/tetragon/pkg/metrics"
+	"github.com/cilium/tetragon/pkg/metrics/consts"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type Key struct {
+	id     uint32
+	attach string
+}
+
+type Stat struct {
+	policy string
+	missed float64
+}
+
+var (
+	MissedProbes = metrics.NewBPFCounter(prometheus.NewDesc(
+		prometheus.BuildFQName(consts.MetricsNamespace, "", "missed_probes_total"),
+		"The total number of Tetragon probe missed per policy,probe.",
+		[]string{"policy", "attach"}, nil,
+	))
+
+	lock  sync.Mutex
+	stats = make(map[Key]Stat)
+)
+
+func Store(id uint32, policy, attach string, missed float64) {
+	key := Key{id, attach}
+	if stat, found := stats[key]; found {
+		stat.missed = missed
+		stats[key] = stat
+	}
+
+	lock.Lock()
+	defer lock.Unlock()
+
+	stats[key] = Stat{
+		policy: policy,
+		missed: missed,
+	}
+}
+
+func Remove(id uint32, attach string) {
+	lock.Lock()
+	defer lock.Unlock()
+	delete(stats, Key{id, attach})
+}