Observability
Prometheus alerting rules can fail silently for years: a typo in a PromQL expression, a label mismatch in Alertmanager routing, or a threshold that never actually fires. promtool provides a native unit testing framework for alert rules—YAML-defined tests that validate expressions against synthetic time-series data without running a live
SRE
SLI, SLO, and error budget are the vocabulary of reliability engineering. They give you a rigorous way to answer "is our service reliable enough?" and "how much risk can we take with this deployment?" without relying on gut feeling or incident retrospectives. This guide covers how
SRE
Synthetic monitoring runs scripted tests against your application continuously — from multiple geographic locations, using real browsers or API clients — to detect issues before users report them. Combined with canary deployments, it becomes your automated deployment safety net. Synthetic Monitoring Fundamentals Synthetic monitors are different from real user monitoring (RUM): Synthetic
SRE
When an incident happens at 3 AM, the quality of your response depends on two things: the quality of your runbooks and how many times your team has practiced them. Testing runbook automation and running incident drills converts theory into muscle memory. Automated Runbooks vs. Reference Runbooks Reference runbooks are
SRE
High availability is a promise — that your system will remain operational when components fail. Multi-region failover is how you keep that promise when an entire cloud region becomes unavailable. Testing your HA architecture requires deliberately causing the failures your system claims to handle. HA Architecture Patterns Active-passive (warm standby): Traffic
SRE
Chaos engineering is the practice of deliberately introducing failures into a system to discover weaknesses before they cause incidents. Netflix coined the term with Chaos Monkey — a tool that randomly terminates EC2 instances to force engineers to build resilient services. For Kubernetes workloads, Litmus Chaos has become the most widely
SRE
Disaster recovery plans that exist only in documentation are not plans — they're aspirations. The difference between a DR plan that works and one that fails during an actual disaster is whether you've tested it. This guide covers the three tiers of DR testing: tabletop exercises, game