Add support for Healthchecks to monitor Diun watcher (#78)

internal/app/hc.go

@@ -0,0 +1,59 @@
+package app
+
+import (
+	"bytes"
+	"context"
+	"text/template"
+
+	"github.com/crazy-max/diun/v4/internal/model"
+	"github.com/crazy-max/gohealthchecks"
+	"github.com/rs/zerolog/log"
+)
+
+func (di *Diun) HealthchecksStart() {
+	if di.hc == nil {
+		return
+	}
+
+	if err := di.hc.Start(context.Background(), gohealthchecks.PingingOptions{
+		UUID: di.cfg.Watch.Healthchecks.UUID,
+	}); err != nil {
+		log.Error().Err(err).Msgf("Cannot send Healthchecks start event")
+	}
+}
+
+func (di *Diun) HealthchecksSuccess(entries *model.NotifEntries) {
+	if di.hc == nil {
+		return
+	}
+
+	var logsBuf bytes.Buffer
+	logsTpl := template.Must(template.New("").Parse(`{{ .CountTotal }} tag(s) have been scanned:
+* {{ .CountNew }} new tag(s) found
+* {{ .CountUpdate }} tag(s) updated
+* {{ .CountUnchange }} tag(s) unchanged
+* {{ .CountError }} tag(s) with error`))
+	if err := logsTpl.Execute(&logsBuf, entries); err != nil {
+		log.Error().Err(err).Msgf("Cannot create logs for Healthchecks success event")
+	}
+
+	if err := di.hc.Success(context.Background(), gohealthchecks.PingingOptions{
+		UUID: di.cfg.Watch.Healthchecks.UUID,
+		Logs: logsBuf.String(),
+	}); err != nil {
+		log.Error().Err(err).Msgf("Cannot send Healthchecks success event")
+	}
+}
+
+func (di *Diun) HealthchecksFail(logs string) {
+	if di.hc == nil {
+		return
+	}
+
+	if err := di.hc.Fail(context.Background(), gohealthchecks.PingingOptions{
+		UUID: di.cfg.Watch.Healthchecks.UUID,
+		Logs: logs,
+	}); err != nil {
+		log.Error().Err(err).Msgf("Cannot send Healthchecks fail event")
+	}
+}