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Lessons (31)

• Troubleshooting Playbook

  … Attach a temporary one: bash kubectl debug -it <pod --image=busybox:1.36 --target=<container kubectl debug node …

• Debug Latency Like an Investigator

  High CPU is not required for high latency. Follow percentile shape and trace wait time before scaling blindly …

• L6 Production Debugging Casebook

  … See [latency investigation](./debugging-latency) and [observability](./observability-and-incidents). 2. Twelve partitions and fifteen consumers Only twelve …

• Design a Logging and Monitoring Platform

  … During an outage, debug logging increases tenfold and the search cluster falls behind. What must be true Keep …

• Rust: Types, Errors and Concurrency

  … Status, } [derive(Debug, Clone, PartialEq)] enum Status { Pending, Paid { amount cents: u64 }, Shipped { tracking: String }, Cancelled(String), // reason …

• Service Communication: Sync vs Async

  … Any failure = whole request fails. ✅ Simple to understand and debug; you get an immediate answer . ❌ Temporal coupling : every …

• Choosing a Programming Language

  … Errors and<br/ debugging"] -- E["5. Modules and<br/ packages"] -- F["6. Tests"] -- G["7. Concurrency<br/ model …

• Event-Driven Architecture

  … when saving + publishing Transactional outbox pattern Hard to debug "what happened?" Correlation IDs, distributed tracing, an event catalog …

• Putting AI Systems into Production

  … Keep traces useful for debugging while redacting secrets and minimizing personal data. Human review and release criteria Decide …

• Secrets, Ephemeral Values, and Least Privilege

  … Suppress debug logs unless necessary; inspect them for sensitive content before sharing. terraform output -json and -raw can …

• Python Web APIs: FastAPI and Django

  … Django security essentials Setting / habit Why --- --- DEBUG = False in production Debug pages leak settings and code SECRET KEY …

• Cluster Networking, DNS and NetworkPolicies

  … lowering ndots via dnsConfig , or running NodeLocal DNSCache . Debug DNS: bash kubectl run -it --rm dns-test --image …

• What Is Clean Code?

  … Which one would you rather debug at 2 a.m.? ❌ Hard to read js function calc(a, b …

• Pods: Where Your App Actually Runs

  … A random large request wastes capacity; no request makes scheduling and autoscaling less reliable. Four debugging commands to …

• Monolith vs Microservices

  … can be contained ✅ Simplicity ✅ One codebase, easy to debug ❌ Distributed system complexity Calls between parts ✅ Fast, in-memory …

• State Management (Redux, Zustand, TanStack Query)

  … strict conventions, excellent DevTools (time-travel debugging) and middleware. RTK Query adds server-state caching, similar to TanStack …

• REST vs GraphQL vs gRPC

  … t human-readable, and it needs tooling for debugging. Side-by-side comparison REST GraphQL gRPC --- --- --- --- Style Resources …

• Microkernel (Plugin) Architecture

  … isolation Plug-in interactions can be hard to debug Customisation per customer/region without forks Performance overhead of …

• Internals, Upgrades, Resilience and Interview Questions

  … How do you debug a pod in CrashLoopBackOff? describe for events and exit code, logs --previous for the …

• Serverless Architecture

  … managed services are provider-specific Local testing and debugging Harder; use emulators (SAM, LocalStack) and good tracing Observability …

• Authentication, Authorization & API Security

  … Rate limits per user/IP (429) Security misconfiguration Debug mode in prod, open CORS with credentials, default passwords …

• Observability: Logs, Metrics & Traces

  … failed"} Log levels Level Use for In production? --- --- --- debug Detailed developer info Usually off info Normal business events …

• CQRS & Event Sourcing

  … report? Replay all events into a new projection 🐛 Debugging Replay the exact sequence of events that caused a …

• Choosing an Architecture

  … to the same facts, integration, buffering Eventual consistency, debugging Microkernel Small core + plug-ins Extensible products, per-customer …

• Containers at Scale: ECS Deep Dive and EKS

  … gives a shell into a running task for debugging, audited through CloudTrail. - Enable Container Insights for CPU, memory …

• Code Profiling

  … do not log private order data just to debug performance. Capture a CPU profile For a local or …

• VPC Networking Without the Confusion

  … and database private; expose only the load balancer. - Debug network problems hop by hop: DNS → route → security group …

• AWS Databases: Choose the Right One

  … A public IP and a broad firewall rule are not necessary just to debug it; use an approved …

• Rust: Ownership, Borrowing and Lifetimes

  … src/main.rs cargo run build and run (debug) cargo build --release optimised build cargo test unit + integration …

• Practical Lab: S3 File Upload and CloudFront Delivery with NestJS

  … on your own account, plus the tools to debug it when it does not. Placeholders: commands use ACCOUNT …

• Practical Project: Deploy a Real CRM App on EKS

  … for your own containerized application and, more importantly, debug it when it breaks. Placeholders: commands use ACCOUNT ID …