Span Contracts: Trace-Driven API Contract Testing with OpenTelemetry
Detect API breaking changes by hashing response shapes from OTel spans and fail CI without storing payloads.
#testing
7 posts
Cardinality Contracts: Prometheus Labels as an API with Budgets
Define label budgets, enforce them in CI, and add a runtime firewall to stop cardinality explosions before production.
Dash Contracts in Go: CI Compiler for Grafana Dashboards and Prometheus Alerts
Extract PromQL from dashboards and rules, verify selectors against /metrics, and fail CI before dashboards go dark.
5000 Unacked Messages and Climbing: Stop RabbitMQ Consumer Meltdowns in CI
Queue looks healthy until deployment, then messages_unacknowledged explodes, memory spikes, and redelivery storms start. The culprit: your prefetch is too high and nobody tested actual ack behavior.
One Partition at 99% CPU: Stop Kafka Hotspots Before They Reach Production
All partitions look balanced in testing, then production traffic arrives and one partition melts. The culprit: your partition key has terrible cardinality and nobody noticed until now.
Fields Disappeared But Nothing Crashed: Catch Schema Evolution Bugs Before Production
Producer upgraded Protobuf, consumer still on old version. No errors, no warnings—just silent data loss in production. Your schema evolution broke backward compatibility and CI didn't notice.
Stop Mocking Your Database: Integration Tests in the Testcontainers Era
Why mocks lie and how Testcontainers will change your testing approach. Practical examples, CI setup, and data isolation strategies.