Caching Elm downloads on Netlify builds

[dillonkearns]

Hello all,

Evan requested that people take some time to make sure their Elm downloads are being cached on their CI environments. I came up with a solution for Netlify builds.

Here’s what the change looks like in your netlify.toml config:

[build]
  publish = "./dist/"
-  command = "npm run build"
+  command = "export ELM_HOME=\"$NETLIFY_CACHE_DIR/elm\" && npm run build"

I updated the elm-pages-starter repo with that config for anybody who uses that template going forward:

Save Elm cache in netlify cache directory.

The details

Here’s the before and after:

It’s nice to shave off a few seconds (on average) from the build, and make it more resilient in case there is ever an outage.

I’m sure there could be a more elegant solution here for how to set the environment variable in Netlify. I played around with it for a while and had trouble getting it to work writing it with this alternative that I saw in these docs:

[build.environment]
  # doesn't seem to work
  ELM_HOME = "$NETLIFY_CACHE_DIR/elm"

But that’s just a minor aesthetic issue. Otherwise, everything seems to be working smoothly!

Hope that’s helpful for others!