Remove objects from cache when processing Icinga 2 delete event

internal/icinga2/client.go

@@ -7,10 +7,12 @@ import (
 	"github.com/google/uuid"
 	lru "github.com/hashicorp/golang-lru/v2"
 	"github.com/icinga/icinga-notifications/internal/event"
+	"github.com/icinga/icinga-notifications/internal/object"
 	"go.uber.org/zap"
 	"golang.org/x/sync/errgroup"
 	"net/http"
 	"net/url"
+	"strings"
 	"time"
 )
 
@@ -190,6 +192,17 @@ func (client *Client) deleteExtraTagsCacheFor(result *ObjectCreatedDeleted) erro
 		return fmt.Errorf("cannot delete object extra tags for unknown object_type %q", result.ObjectType)
 	}
 
+	if result.EventType == typeObjectDeleted {
+		names := strings.Split(result.ObjectName, "!")
+		tags := map[string]string{"host": names[0]}
+		if len(names) == 2 {
+			tags["service"] = names[1]
+		}
+
+		// Delete the object from our global cache to avoid having huge dangling objects that don't exist in Icinga 2.
+		object.DeleteFromCache(object.ID(client.EventSourceId, tags))
+	}
+
 	// The checkable has just been either deleted or created, so delete all existing extra tags from our cache
 	// store as well and will be refreshed on the next access when Icinga 2 emits any other event for that object.
 	client.eventExtraTagsCache.Remove(result.ObjectName)

internal/object/objects.go

@@ -17,6 +17,14 @@ var (
 	cacheMu sync.Mutex
 )
 
+// DeleteFromCache deletes the Object from the global cache store matching the given ID (if any).
+func DeleteFromCache(id types.Binary) {
+	cacheMu.Lock()
+	defer cacheMu.Unlock()
+
+	delete(cache, id.String())
+}
+
 // RestoreMutedObjects restores all muted objects and their extra / ID tags from the database.
 // Note, this function only retrieves muted objects without non-recovered incident.
 //