Buglyst Blog
Learn to debug under pressure.
Playbooks for fast pattern recognition, guides for the full investigation, and articles for the engineering judgment around the edges.
17 playbooks · 509 guides · 95 articles · 12 linked practice labs ·skip to practice
Fast pattern recognition for the production failures engineers see most often.
2 playbooks in Infrastructure & Cloud
Debugging Env Var Issues
A concise checklist for incidents where local works but CI, staging, or production changes behavior.
Debugging Deployment Config Bugs
How to debug incidents where the source is deployment wiring rather than application logic.
Structured investigations for the failure modes engineers meet in real systems.
Environment variable undefined in production: how to debug it
Your app reads `process.env.DATABASE_URL` and gets `undefined` in production — but it works locally. Track down the injection gap.
Docker container cannot connect to localhost: how to debug it
Your app inside Docker tries to reach a service on localhost and gets connection refused. The fix is understanding Docker networking.
Node version mismatch in CI: how to debug it
Your code uses a feature from Node 20 but CI runs Node 18. Build fails with a syntax error or missing API. The fix is one line in the CI config.
npm install works locally but fails in CI: how to debug it
npm install completes on your machine but CI throws errors. The issue is usually a clean environment gap: missing native build tools, lockfile drift, or platform-specific binaries.
File upload works locally but fails in production: how to debug it
Your upload endpoint works with local files but returns errors in production. The filesystem, permissions, size limits, or storage backend is different.
Deployment config mismatch: how to debug environment-specific config bugs
Your staging environment works. Production does not. The code is the same but the config is different — a missing setting, a wrong endpoint, or a different feature flag value.
Long-form thinking on debugging habits, observability, and the systems around the bug.
Chaos Engineering at 3 AM: When Our Kubernetes Cluster Lost Its DNS
We ran a chaos experiment on our Kubernetes cluster and found a subtle DNS misconfiguration that would have caused a cascading failure. Here's how we did it and what we learned.
Debugging Inside Docker Containers: Tools, Techniques, and a War Story
Practical techniques for debugging inside Docker containers: exec, nsenter, strace, and a real incident that made me rethink debug images.
kubectl logs: Debugging Pods with Logs, Timestamps, and Previous Instances
Beyond `kubectl logs pod-name` — using timestamps, previous instances, and multi-container patterns to diagnose real failures.
Debugging Serverless Functions Locally: A Practical Approach
Local debugging of serverless functions requires different tools and mindset than traditional apps. Here's how I approach it with real examples.
Debugging Terraform and CloudFormation Errors: A Field Guide to the 3 AM Page
Infrastructure-as-code errors are inevitable. Here's how to systematically debug Terraform and CloudFormation failures without losing your mind.