Prometheus alert rules:
Prometheus alert rules: verify metric existence before writing PromQL. Wrote 6 CIOS alert rules using up{job=paperclip} — these metrics do not exist because CIOS containers have no Prometheus scrape targets (app containers, not exporters). Rules loaded without error but immediately false-positived. Fix: Use container_last_seen{name=container} from cAdvisor. Pattern: time() - container_last_seen{name=paperclip} > 120 with for: 2m. Rule: Before writing ANY PromQL expression, verify metric exists: curl -s http://localhost:9090/api/v1/query?query=metric{labels} | jq .data.result | length. cAdvisor metrics (container_*) always available for Docker containers. up{job=…} only works for containers with dedicated scrape targets.