1 files changed, 114 insertions, 0 deletions
diff --git a/internal/metrics/metrics.go b/internal/metrics/metrics.go
new file mode 100644
index 0000000..aae46cd
--- /dev/null
+++ b/internal/metrics/metrics.go
@@ -0,0 +1,114 @@
+package metrics
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"rgdd.se/silentct/internal/monitor"
+	"rgdd.se/silentct/pkg/storage/index"
+)
+
+type Metrics struct {
+	errorCounter               prometheus.Counter
+	logIndex                   *prometheus.GaugeVec
+	logSize                    *prometheus.GaugeVec
+	logTimestamp               *prometheus.GaugeVec
+	needRestart                prometheus.Gauge
+	unexpectedCertificateCount *prometheus.GaugeVec
+}
+
+func NewMetrics(registry *prometheus.Registry) *Metrics {
+	m := &Metrics{
+		errorCounter: prometheus.NewCounter(
+			prometheus.CounterOpts{
+				Name: "silentct_error_counter",
+				Help: "The number of errors propagated to the main loop.",
+			},
+		),
+		logIndex: prometheus.NewGaugeVec(
+			prometheus.GaugeOpts{
+				Name: "silentct_log_index",
+				Help: "The next log entry to be downloaded.",
+			},
+			[]string{"log_id", "log_name"},
+		),
+		logSize: prometheus.NewGaugeVec(
+			prometheus.GaugeOpts{
+				Name: "silentct_log_size",
+				Help: "The number of entries in the log.",
+			},
+			[]string{"log_id", "log_name"},
+		),
+		logTimestamp: prometheus.NewGaugeVec(
+			prometheus.GaugeOpts{
+				Name: "silentct_log_timestamp",
+				Help: "The log's UNIX timestamp in ms.",
+			},
+			[]string{"log_id", "log_name"},
+		),
+		needRestart: prometheus.NewGauge(
+			prometheus.GaugeOpts{
+				Name: "silentct_need_restart",
+				Help: "A non-zero value if the monitor needs restarting.",
+			},
+		),
+		unexpectedCertificateCount: prometheus.NewGaugeVec(
+			prometheus.GaugeOpts{
+				Name: "silentct_unexpected_certificate_count",
+				Help: "Number of certificates without any allowlisting",
+			},
+			[]string{"log_id", "log_name", "log_index", "crt_sans"},
+		),
+	}
+	registry.MustRegister(
+		m.errorCounter,
+		m.logIndex,
+		m.logSize,
+		m.logTimestamp,
+		m.needRestart,
+		m.unexpectedCertificateCount,
+	)
+	return m
+}
+
+func (m *Metrics) LogState(logName string, state monitor.State) {
+	labels := prometheus.Labels{
+		"log_id":   fmt.Sprintf("%x", state.LogID[:]),
+		"log_name": logName,
+	}
+	m.logIndex.With(labels).Set(float64(state.NextIndex))
+	m.logSize.With(labels).Set(float64(state.TreeSize))
+	m.logTimestamp.With(labels).Set(float64(state.Timestamp))
+}
+
+func (m *Metrics) RemoveLogState(logName string, state monitor.State) {
+	labels := prometheus.Labels{
+		"log_id":   fmt.Sprintf("%x", state.LogID[:]),
+		"log_name": logName,
+	}
+	m.logIndex.Delete(labels)
+	m.logSize.Delete(labels)
+	m.logTimestamp.Delete(labels)
+}
+
+func (m *Metrics) UnexpectedCertificateCount(logNames []string, alerts []index.CertificateInfo) {
+	m.unexpectedCertificateCount.Reset()
+	for i, alert := range alerts {
+		labels := prometheus.Labels{
+			"crt_sans":  strings.Join(alert.SANs, " "),
+			"log_id":    fmt.Sprintf("%x", alert.LogID),
+			"log_name":  logNames[i],
+			"log_index": fmt.Sprintf("%d", alert.LogIndex),
+		}
+		m.unexpectedCertificateCount.With(labels).Set(1)
+	}
+}
+
+func (m *Metrics) CountError() {
+	m.errorCounter.Inc()
+}
+
+func (m *Metrics) NeedRestart() {
+	m.needRestart.Set(float64(1))
+}