In a previous post, I discussed the long build time of my website. However, this isn’t the only thing bogging down my ci usage. Simply setting up the environment was taking 1-3 minutes.

I tried to use nix in CI because it was easy. There were ready made github actions, and nix took care of installing everything reproducibly. I thought I would appreciate using the same environment in CI as locally.

However, nix installs your entire dependency tree, all the way down to libc and a shell if needed. When working locally, all this is cached so your not redownloading the world every time you tweak your environment. Caching was not working in CI for whatever reasons, and only a few megabytes of dependencies out of several gigabytes were being cached.

I switched to github actions that install each of my dependencies separately (one action for each of hugo, asciidoctor, and go). They all run in seconds when their caching works, and tens of seconds otherwise. And they use what the CI operating system provides, so only a few mb’s of dependencies are downloaded instead of GB’s.

I reduced my CI time from 3 minutes to 1. I should have done this from the start instead of hopping on a bandwagon. Nix still seems cool though.