Q: Your team manages an application that writes millions of logs to disk each hour. Suddenly, all disks across the fleet fill up simultaneously, causing a massive outage. What is the fundamental architecture flaw, and how do you fix it?
The architectural flaw is storing unbounded state (logs) on the application instance's local filesystem without rotation.
#General DevOps #General DevOps — Scenario-Based Interview Questions #L2 #DevOps #SRE #Architecture
🎙️ Candidate Opening & Architectural Context
""When an interviewer asks about this scenario, I explain how we balanced incident response with long-term prevention. The interviewer is testing: Log rotation, log shipping, decoupling state.. I structure my answer around systematic triage first, root cause analysis second, and permanent remediation third.""
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🛠️ Production Runbook & Step-by-Step Resolution
1️⃣
Initial Diagnostics & Root Cause Analysis
The architectural flaw is storing unbounded state (logs) on the application instance's local filesystem without rotation.
- Log Rotation: Immediately configure
logrotateto compress and delete logs older than a few hours or when they exceed a certain MB threshold. This caps the maximum disk usage. - Decoupling State: In modern DevOps (e.g., Docker/Kubernetes), applications shouldn't manage log files on disk at all. Applications should log purely to
STDOUTandSTDERR. A DaemonSet or sidecar agent (like Fluentbit or Filebeat) acts as a pipe, reading those streams and shipping them entirely off the host to a centralized aggregator (Datadog/Elasticsearch) preventing local disk exhaustion completely.
2️⃣
Remediation & Permanent Safeguards
An SRE fix involves:
💡 The Senior SRE Gold Nugget (Key Architectural Takeaway)
"Pro-Tip: Log Rotation: Immediately configure logrotate to compress and delete logs older than a few hours or when they exceed a certain MB ."
⚡ 60-Second Elevator Pitch Talking Points
- Log Rotation: Immediately configure logrotate to compress and delete logs older than a few hours ...
- Decoupling State: In modern DevOps (e.g., Docker/Kubernetes), applications shouldn't manage log f...
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