feat(mastodon): Add SLO for sidekiq processing

apps/k8s01/mastodon/slo.yaml

@@ -6,6 +6,19 @@ metadata:
 spec:
   service: "mastodon"
   slos:
+    - name: "sidekiq-failures"
+      objective: 95
+      description: "Mastodon: SLO based on failed jobs in sidekiq."
+      sli:
+        events:
+          errorQuery: (sum(rate(sidekiq_failed_jobs_total{namespace="mastodon"}[{{.window}}]))
+          totalQuery: sum(rate(sidekiq_processed_jobs_total{namespace="mastodon"}[{{.window}}]) + rate(sidekiq_failed_jobs_total{namespace="mastodon"}[{{.window}}]))
+      alerting:
+        name: MastodonSidekiqProccessingHighErrorRate
+        labels:
+          category: "availability"
+        annotations:
+          summary: "High sidekiq job failure rate for Mastodon"
     - name: "requests-availability"
       objective: 98
       description: "Mastodon: SLO based on availability for HTTP request responses."