Dwight Watson's blog

Gzip static assets in Phoenix

This blog post was originally published a little while ago. Please consider that it may no longer be relevant or even accurate.

Recently I've been playing with Phoenix, the hot framework for Elixir. While it has a definite Rails vibe there's also a very different flavour because of the nature of it being written in a functional language. Oddly enough reading Refactoring to Collections, a book written mainly for the PHP community, has eased the transition to functional coding.

Having just deployed my first example app on Heroku I was seeing some pretty good speeds - page loads in under 1s. But not the wow I was expecting from moving to Phoenix. Turns out, there's a quick tweak you can make to your Phoenix application so that your assets are gzipped in production. Simply edit your lib/app/endpoint.ex file.

plug Plug.Static,
at: "/", from: :lunchmates, gzip: true,
only: ~w(css fonts images js favicon.ico robots.txt)

It's mentioned in the comment above it, but by enabling the gzip option (which is off by default), you'll get a significant performance boost out of your static assets.

On a related note, despite the fact that Phoenix hashes your static assets filenames' so they can be cachebusted, it still adds a ?vsn=n query string to the end of the path. There was an issue and related PR to remove this, or make it optional, but it was rejected. I do hope at some point they'll reconsider this, because having it there is unneccessary, and a little ugly.

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