Migrating this blog from Tailwind v3 to v4
Moved this blog from Tailwind v3 to v4. The big change is that configuration left tailwind.config.js and went into the CSS itself, using @theme.
TIL — Today I Learned
Quick notes and discoveries from my learning journey
Idempotency keys stop duplicate charges
On a charge endpoint, a retry or a double click can turn one payment into two. The fix is an idempotency key. The caller sends...
Verifying an ECDSA signature in Go
We had a server-to-server callback that came signed, and I needed to verify it in Go. The flow is short: parse the public key (usually...
Postgres partial indexes for a WHERE you always use
We had a slow query that filtered on a column where almost every row held the same value, and only a small slice was the...
Go 1.21 added min, max, and clear
After upgrading to Go 1.21, I deleted a few tiny helper functions I had been carrying around for years.
find vs find_by to avoid noisy errors
Our error tracker was full of RecordNotFound exceptions for cases that were completely fine. A missing row was expected, not a real problem.
context.WithTimeout won't stop a blocking call
I assumed context.WithTimeout would cancel anything once the deadline passed. It does not. It only signals. Your code has to actually watch the context for...
closure_tree: filter early
In a side project I use the closure_tree gem for hierarchical data in Rails. Methods like #leaves and #hash_tree are handy, but once I added...
Set max idle connections, not just max open
Under load we kept getting “bad connection” errors that came and went. The connection pool had a sane max open setting, so that was not...
Events that must stay ordered go in the same Kafka topic
Kafka only guarantees order within a single partition. Not across partitions, and definitely not across topics.
A good circuit-breaker fallback is the last cached response
When a circuit breaker opens because a downstream is failing, you stop calling it for a while to let it recover. The question is what...
Quorum is ceil(N/2)
Quorum is the smallest number of nodes that have to agree before a decision counts. The formula is ceil(N/2):
Rewrite the commit author across history
Committed a bunch of work with the wrong author name, and some with a personal email I did not want public. Fixing the latest commit...
Delete all evicted pods in one line
Evicted pods pile up and clutter kubectl get pods. They are done, they just sit there. Here is a one-liner to clean them up across...
Every net/http request runs in its own goroutine
In Go’s net/http, the server starts a new goroutine for each incoming request. So your handlers run concurrently by default, even if you never wrote...
Killing an N+1 with preload
A hot read endpoint was slow and I could not see why from the code. Watching the query log gave it away: one query to...
Pipe a .sql dump into a Postgres container
Needed to load a SQL dump into Postgres running under docker compose. The obvious pipe:
Why bundle exec actually matters
Spent way too long on a build that worked for me but broke for a teammate. Same repo, different output.