Graceful shutdown and what SIGTERM starts
Your deploy sends SIGTERM. What your process does in the next thirty seconds decides whether someone gets charged twice.
Mudit's Notebook
Things I worked out, written down before I forget them.
Logging, monitoring and observability
Monitoring tells you something is broken. Observability tells you what. The gap between those two sentences is three pillars of instrumentation.
Error handling and building fault tolerant systems
A 500 with "something went wrong" is usually a bug you forgot to name. Catch errors in one place and name them properly.
Configuration management beyond secrets
Config is not just your database URL and your Stripe key. It is every decision your code defers until startup.
Full text search and the inverted index
LIKE '%laptop%' scans every row and has no idea which result matters. An inverted index fixes both problems at once.
Caching, and knowing what to throw away
A cache is a subset of your data kept somewhere faster. Everything hard about it is deciding which subset, and when to throw it away.
Task queues and background jobs
Your signup endpoint should not be waiting on someone else's SMTP server. Push the email into a queue and return.
Why you need a database and not a file
A database is a text file that also enforces the rules you were planning to enforce in application code, and never gets them wrong.
Backend authentication, from sessions to OAuth
Sessions, JWTs, API keys, and OAuth solve four different problems. Picking the wrong one costs you revocation.
Request validation on the backend
Frontend validation is for user experience. Backend validation is for data integrity. Skipping the second one turns a 400 into a 500.
Serialization and the format in the middle
Your JavaScript object and the server's Rust struct have nothing in common. Serialization is the agreed-upon format in the middle.
Routing, from method and path to handler
Routing is a lookup table. The method says what you want, the path says where — together they pick exactly one handler.
Designing a REST API before you write it
Routes, methods, status codes and list parameters are decisions you make in an HTTP client, not while writing handlers.
How to structure a backend
Handlers, services, repositories, middleware, and request context are five answers to one question - where does this line of code belong?
HTTP for backend engineers
Statelessness, headers, CORS preflights and ETags — the parts of HTTP that show up in a network tab at 2am.