Observability
ELI5 — The Vibe Check
Observability is the ability to understand what's happening inside your system from the outside, using three types of data: metrics (numbers), logs (events), and traces (request journeys). A highly observable system lets you ask 'why is this slow?' and actually answer it, even if the problem is brand new and you've never seen it before.
Real Talk
Observability is the degree to which the internal state of a system can be inferred from external outputs. The three pillars are metrics (time-series aggregates), logs (discrete events), and traces (distributed request paths). Observable systems enable debugging novel failure modes without predefined dashboards.
When You'll Hear This
"We need better observability — we're flying blind when production issues happen." / "Good observability means you can answer any question about system behavior from the data."
Related Terms
APM (Application Performance Monitoring)
APM is monitoring on steroids — it doesn't just track if your app is up, it tracks exactly how fast each function runs, which database queries are slow, wh...
Logging
Logging is writing a diary for your program.
Metrics
Metrics are the numbers your app tracks about itself over time — requests per second, error rate, CPU usage, response time, active users.
Monitoring
Monitoring is keeping a constant eye on your app while it runs — tracking whether it's up, how fast it responds, how many errors it throws, and how much me...
Service Mesh
In a microservices system, every service needs to handle retries, timeouts, mutual TLS, and send traces. You could code all that in every service.