#developer-tools

The shape I give small tools: one file, one job, sections in a fixed order, an exit-code contract at the top, and three ways in for input — plus its Bash variant for generators, and when a tool outgrows it.

SMTP and IMAP credentials fail late and far from their cause: a reset email that never arrives. A small check proves both directions first, with a tokenised test message, a read-only inbox check, and broken config kept distinct from a broken server.

Commands I run four times a year are the expensive case: I remember their shape, not their syntax, and get something plausible but wrong. Three scripts hold the decisions, and their guards depend on whether there is a choice I could get wrong, not on danger.

Free converters stamp a watermark on web assets by design. Four small ffmpeg wrappers do the job locally, and the watermark was the least of it: the real work was choosing the quality, preset and GIF palette flags ffmpeg lets you get wrong.

Photos into one PDF, a PDF under two megabytes, a layout inspected page by page — usually done by uploading to a stranger's website. Three small tools do it locally with Pillow and Ghostscript; the only real decisions were which defaults to bake in.

cp -r drops owner, permissions and timestamps, producing copies that look right and fail in use. A 58-line rsync wrapper makes the destination truly equal to the source — and most of its lines are refusals, because making it equal means agreeing to delete.

Retyping long Docker commands costs seconds, invites typos and taxes working memory. Ten short executables on PATH removed that cost; the interesting decisions were why not aliases, how to keep names guessable, and why one of them is 260 lines long.

A storage server that answers a connection only proves a process is listening. I check each capability separately — browser uploads via presigned URL, private buckets refusing strangers, large files through the proxy — before any application depends on it.

A failed login in a half-built service is either a misconfigured identity provider or wrong code. I rule out the first by rehearsing a full login with my own tool before writing any app, and found compliant providers still disagree on tokens and claims.

Logs, traces and metrics from a dozen containers pushed over OTLP into one deliberately dumb collector, then read in Kibana — with a disk queue so a restart loses nothing, audit events counted exactly once, and the rule that telemetry must never become a failure point.

Self-signed certificates cost work in every container, and no HTTPS hides bugs in cookies, redirects and OAuth2. I point the real domain at loopback and install the real certificate at the same path, so my laptop runs the same nginx config as production.

Build output, not my own code, was filling the disk: five projects shrank from 21 GB to 749 MB once the rebuildable folders were gone. I automated that cleanup instead of buying a bigger SSD, without trusting folder names or confirming hundreds of folders by hand.