1 files changed, 203 insertions, 0 deletions
diff --git a/pkg/icingaredis/telemetry/heartbeat.go b/pkg/icingaredis/telemetry/heartbeat.go
new file mode 100644
index 0000000..ee476a1
--- /dev/null
+++ b/pkg/icingaredis/telemetry/heartbeat.go
@@ -0,0 +1,203 @@
+package telemetry
+
+import (
+	"context"
+	"fmt"
+	"github.com/go-redis/redis/v8"
+	"github.com/icinga/icingadb/internal"
+	"github.com/icinga/icingadb/pkg/com"
+	"github.com/icinga/icingadb/pkg/icingaredis"
+	"github.com/icinga/icingadb/pkg/logging"
+	"github.com/icinga/icingadb/pkg/periodic"
+	"github.com/icinga/icingadb/pkg/utils"
+	"github.com/pkg/errors"
+	"go.uber.org/zap"
+	"regexp"
+	"runtime/metrics"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+// ha represents icingadb.HA to avoid import cycles.
+type ha interface {
+	State() (weResponsibleMilli int64, weResponsible, otherResponsible bool)
+}
+
+type SuccessfulSync struct {
+	FinishMilli   int64
+	DurationMilli int64
+}
+
+// currentDbConnErr stores ongoing errors from database connections.
+var currentDbConnErr struct {
+	mu         sync.Mutex
+	message    string
+	sinceMilli int64
+}
+
+// UpdateCurrentDbConnErr updates the current error information stored in currentDbConnErr.
+func UpdateCurrentDbConnErr(err error) {
+	now := time.Now().UnixMilli()
+
+	currentDbConnErr.mu.Lock()
+	defer currentDbConnErr.mu.Unlock()
+
+	if currentDbConnErr.sinceMilli >= now {
+		// Already updated with a more recent error, ignore this one.
+		return
+	}
+
+	message := ""
+	if err != nil {
+		message = err.Error()
+	}
+
+	if currentDbConnErr.message == message {
+		// Error stayed the same, no update needed, keeping the old timestamp.
+		return
+	}
+
+	if currentDbConnErr.message == "" || message == "" {
+		// Either first error or recovery from an error, update timestamp.
+		currentDbConnErr.sinceMilli = now
+	}
+
+	currentDbConnErr.message = message
+}
+
+// GetCurrentDbConnErr returns the last error message (or the empty string if not in an error state) and a timestamp in
+// milliseconds of the last change from OK to error or from error to OK.
+func GetCurrentDbConnErr() (string, int64) {
+	currentDbConnErr.mu.Lock()
+	defer currentDbConnErr.mu.Unlock()
+
+	return currentDbConnErr.message, currentDbConnErr.sinceMilli
+}
+
+// OngoingSyncStartMilli is to be updated by the main() function.
+var OngoingSyncStartMilli int64
+
+// LastSuccessfulSync is to be updated by the main() function.
+var LastSuccessfulSync com.Atomic[SuccessfulSync]
+
+var boolToStr = map[bool]string{false: "0", true: "1"}
+var startTime = time.Now().UnixMilli()
+
+// StartHeartbeat periodically writes heartbeats to Redis for being monitored by Icinga 2.
+func StartHeartbeat(
+	ctx context.Context, client *icingaredis.Client, logger *logging.Logger, ha ha, heartbeat *icingaredis.Heartbeat,
+) {
+	goMetrics := NewGoMetrics()
+
+	const interval = time.Second
+
+	var lastErr string
+	var silenceUntil time.Time
+
+	periodic.Start(ctx, interval, func(tick periodic.Tick) {
+		heartbeat := heartbeat.LastReceived()
+		responsibleTsMilli, responsible, otherResponsible := ha.State()
+		ongoingSyncStart := atomic.LoadInt64(&OngoingSyncStartMilli)
+		sync, _ := LastSuccessfulSync.Load()
+		dbConnErr, dbConnErrSinceMilli := GetCurrentDbConnErr()
+		now := time.Now()
+
+		values := map[string]string{
+			"version":                 internal.Version.Version,
+			"time":                    strconv.FormatInt(now.UnixMilli(), 10),
+			"start-time":              strconv.FormatInt(startTime, 10),
+			"error":                   dbConnErr,
+			"error-since":             strconv.FormatInt(dbConnErrSinceMilli, 10),
+			"performance-data":        goMetrics.PerformanceData(),
+			"last-heartbeat-received": strconv.FormatInt(heartbeat, 10),
+			"ha-responsible":          boolToStr[responsible],
+			"ha-responsible-ts":       strconv.FormatInt(responsibleTsMilli, 10),
+			"ha-other-responsible":    boolToStr[otherResponsible],
+			"sync-ongoing-since":      strconv.FormatInt(ongoingSyncStart, 10),
+			"sync-success-finish":     strconv.FormatInt(sync.FinishMilli, 10),
+			"sync-success-duration":   strconv.FormatInt(sync.DurationMilli, 10),
+		}
+
+		ctx, cancel := context.WithDeadline(ctx, tick.Time.Add(interval))
+		defer cancel()
+
+		cmd := client.XAdd(ctx, &redis.XAddArgs{
+			Stream: "icingadb:telemetry:heartbeat",
+			MaxLen: 1,
+			Values: values,
+		})
+		if err := cmd.Err(); err != nil && !utils.IsContextCanceled(err) && !errors.Is(err, context.DeadlineExceeded) {
+			logw := logger.Debugw
+			currentErr := err.Error()
+
+			if currentErr != lastErr || now.After(silenceUntil) {
+				logw = logger.Warnw
+				lastErr = currentErr
+				silenceUntil = now.Add(time.Minute)
+			}
+
+			logw("Can't update own heartbeat", zap.Error(icingaredis.WrapCmdErr(cmd)))
+		} else {
+			lastErr = ""
+			silenceUntil = time.Time{}
+		}
+	})
+}
+
+type goMetrics struct {
+	names   []string
+	units   []string
+	samples []metrics.Sample
+}
+
+func NewGoMetrics() *goMetrics {
+	m := &goMetrics{}
+
+	forbiddenRe := regexp.MustCompile(`\W`)
+
+	for _, d := range metrics.All() {
+		switch d.Kind {
+		case metrics.KindUint64, metrics.KindFloat64:
+			name := "go_" + strings.TrimLeft(forbiddenRe.ReplaceAllString(d.Name, "_"), "_")
+
+			unit := ""
+			if strings.HasSuffix(d.Name, ":bytes") {
+				unit = "B"
+			} else if strings.HasSuffix(d.Name, ":seconds") {
+				unit = "s"
+			} else if d.Cumulative {
+				unit = "c"
+			}
+
+			m.names = append(m.names, name)
+			m.units = append(m.units, unit)
+			m.samples = append(m.samples, metrics.Sample{Name: d.Name})
+		}
+	}
+
+	return m
+}
+
+func (g *goMetrics) PerformanceData() string {
+	metrics.Read(g.samples)
+
+	var buf strings.Builder
+
+	for i, sample := range g.samples {
+		if i > 0 {
+			buf.WriteByte(' ')
+		}
+
+		switch sample.Value.Kind() {
+		case metrics.KindUint64:
+			_, _ = fmt.Fprintf(&buf, "%s=%d%s", g.names[i], sample.Value.Uint64(), g.units[i])
+		case metrics.KindFloat64:
+			_, _ = fmt.Fprintf(&buf, "%s=%f%s", g.names[i], sample.Value.Float64(), g.units[i])
+		}
+	}
+
+	return buf.String()
+}