Design a monitoring and alerting system
PremiumCloud infrastructureMedium
- Time series database
- Alert rules
- Metrics scraping
Quick answer
This cloud infrastructure interview question asks you to design a monitoring and alerting system. Aim for a design that runs reliably and securely in the cloud at a sensible cost, then explain the services, regions, deployment and trade-offs. Interviewers want to see how you balance reliability, security and cost.
The problem
Design a monitoring and alerting system like the metrics stacks most companies run: it collects numeric metrics from servers and services, stores them as time series, draws dashboards and fires alerts when rules match. The hard parts are millions of active series, evaluating rules on time, and never staying silent when monitoring itself breaks.
Each target exposes metrics such as http_requests_total with labels (service, route, status). An alert rule is a query plus a condition and a duration, for example: error rate above 2% for 5 minutes.
What must a monitoring and alerting system do?
- Collection: Scrape metrics from every target every 15 s, and accept pushed metrics from short-lived jobs.
- Storage and query: Store samples per series and answer range queries with functions such as rate, sum by label and percentiles from histograms.
How well must it do it?
- Alert latency: An alert fires within 1 minute after its duration condition is met.
- Monitoring of monitoring: If collection, rule evaluation or notification stops, someone is told within 5 minutes.
What scale should you design for?
Use these numbers in your estimates.
The scale numbers unlock with this questionUnlock
Key concepts
- Time series database
- Alert rules
- Metrics scraping
- Cardinality
- Downsampling
- Meta monitoring
How you’ll practise
- Requirements
- Environments and topology
- Deployment pipeline
- Reliability and disaster recovery
- Observability and cost
- Wrap-up
Lala, personalized to you, gives a hint when you ask and reviews your design when you are ready.
What do interviewers look for?
In any cloud infrastructure design round.
- Clarifies availability, security and cost targets
- Chooses managed services with reasons
- Plans regions, zones and failover
- Covers identity, secrets and network boundaries
- Explains deployment, rollback and observability
- Keeps an eye on cost as usage grows
Questions people ask about this interview question
- Which design type is this question?
- It is a cloud infrastructure question. You design a monitoring and alerting system and explain your choices the way you would in an interview.
- Is this question asked at entry level?
- It is marked Medium. Entry-level engineers can practise it, but it expects you to reason about requirements and trade-offs, not only list components.
- What should I cover first?
- Start with the workloads, the availability target and the security and cost limits. Agree on scope with the interviewer before you design anything.
- Can I practise it for free?
- It is a premium question. Sign up and unlock it once for 10 credits; it then stays unlocked. When you finish, Lala, your personalized AI mentor, can review your design for 30 credits.
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Updated · Written by the SevyDevy team