Observability & Monitoring covers: Observability Engineering, Learning OpenTelemetry, Systems Performance, Learning Elastic Stack. Instrument applications with OpenTelemetry, build dashboards, set up alerting, and understand the three pillars of observability: logs, metrics, and traces. Learn to diagnose performance issues systematically.
OpenTelemetry with Rails. Tracing a request from Nginx to Puma to ActiveRecord to Redis to response. This is where all your Linux, networking, and Docker knowledge comes together.
| Observability Need | Tool/Technique |
|-------------------|----------------|
| Request tracing | OpenTelemetry + Jaeger or Honeycomb |
| Error tracking | Sentry, Honeybadger, or Airbrake |
| APM (app performance) | New Relic, Datadog, or OTel + Grafana |
| Log aggregation | ELK stack or Loki + Grafana |
| Database query analysis | EXPLAIN ANALYZE, pg_stat_statements |
| Memory profiling | derailed_benchmarks, memory_profiler |
| CPU profiling | stackprof, rbspy, flame graphs |
This course unlocks once you've finished its prerequisite. Open prerequisite →
This is the module that will change how you think about production. Not incrementally, fundamentally. Before this module, production is a black box that either works or does not. …
A user emails: "the app was really slow for me yesterday around lunch." You open your dashboards. Average response time: fine. Error rate: fine. CPU: fine. Every graph you built s…
Here's an infrastructure decision that quietly costs teams five figures a year: they instrument their app with one vendor's agent — New Relic's, Datadog's, whoever won the eval — …
Your traces say the checkout endpoint spent 900ms "in Ruby" — no slow SQL, no slow Redis, no external call. The span just… took that long. Application-level observability has walk…
Something broke at 02:14. The evidence is spread across four Puma hosts, two Sidekiq boxes, an Nginx access log, and Postgres's slow-query log — eight files, four machines, one of…
Work through each item before the checkpoint.
Instrument an app with OpenTelemetry and watch a request trace itself through the request handler, the database, and Redis. CI runs a real OTel Collector and checks your spans act…
7 lessons. Read in order; spiral back when you need to. By the end you'll have used the core ideas twice — once on the abstract, once on something you'll meet at work next week.