How would you design observability for a microservices platform?
What they are really testing: Senior signal: a coherent strategy spanning instrumentation, the three signals, SLOs, and cost, plus consistency across services, rather than bolting on a tool. They want the whole system.
A real interview question
How would you design observability for a microservices platform?
What most people say
drag me
“I would install Prometheus and Grafana and add some dashboards.”
Tools are not a strategy. A microservices platform needs consistent instrumentation (OTel + context propagation), correlated signals, per-service SLOs and symptom alerting, and deliberate cost control, not just a dashboarding stack bolted on.
The follow-ups they ask next
How do you keep observability consistent across many teams and services?
Shared OTel instrumentation libraries, a paved-road service template/scaffold, and standards for metric names, labels, and log fields, so observability is built-in by default rather than each team rolling its own.
How do you keep observability costs under control at scale?
Trace sampling (head/tail), deliberate log levels and retention, and bounded metric cardinality. The three signals all explode in cost at scale, so you budget each: sample traces, scope logs, and watch labels.
What the interviewer is listening for
- Standardizes on OTel + context propagation
- Correlated three signals + per-service SLOs + symptom alerting
- Plans cost (sampling/retention/cardinality) and consistency
What sinks the answer
- "Install Prometheus + Grafana" as the whole answer
- No SLOs or context propagation
- Ignores cost and consistency
If you genuinely do not know
Say this instead of freezing. Reasoning out loud from what you do know beats silence every single time, and a good interviewer is listening for exactly that.
“Design it as a platform capability: [standardize on OpenTelemetry + mandatory trace-context propagation], [all three signals correlated, RED + golden-signal metrics, structured logs with trace IDs, distributed traces], [per-service SLOs, golden-signal dashboards, alert on SLO burn with runbooks], and [cost + consistency via sampling/retention/bounded cardinality and shared libraries/paved-road scaffolds].”
Keep going with observability
Foundation
What is the difference between monitoring and observability?
Foundation
What are the three pillars of observability, and what is each good for?
Foundation
What should you measure first for a service? Explain the golden signals (or RED/USE).
Junior
What are good logging practices for a distributed system?
Junior
What are the main metric types (counter, gauge, histogram), and when do you use each?
Junior
What is distributed tracing, and how does it work?
Knowing the answer is not the same as recalling it under pressure
Sign in to send the questions you fumble to spaced recall, so they come back right before you would forget them, and learn the concepts behind them with hands-on labs.
Start free