Update Cache Control

[JKarlavige]

What are you changing in this pull request and why?

This is an effort to improve caching of our docs site to reduce Vercel overages. The strategy here is to cache all images to the browser for up to 31 days. This should reduce network requests on images, thus reducing our Fast Data Transfer and Edge Requests overages.

One thing i'm not 100% clear on is whether retrieving an item from the CDN cache counts towards our Fast Data Transfer. I believe it does, as I see the Request Header x-vercel-cache: HIT consistently across network requests and we are still going over our limit.

CDN requests count towards Edge Requests. And assets loaded from the CDN (such as images), count towards Edge Requests (docs here). So this should be able to help with both overages potentially.

Cache settings

Images: Cache images in browser for 31 days, on CDN for 7 days.
Everything else: Cache everything else on CDN for 1 day, & don't cache on the browser.

Preview

This page has a good amount of images to verify the cache:
https://docs-getdbt-com-git-update-cache-headers-dbt-labs.vercel.app/reference/node-selection/test-selection-examples

In the network tab, reload the page and verify images are now being cached by the browser. You may have to select the Disable cache option within the network tab.

Select an image in the network tab, and verify the Cache-Control matches what is set in the vercel.json within this PR.

Verify that other file types such as css, js, etc. use the fallback Cache-Control of max-age=0, s-maxage=86400 stale-while-revalidate, which caches the item in Vercel's CDN for 1 day.

Notes

I will give the docs team a heads up when replacing images, the new image should have a unique name. If we ever need to bust the browser image cache, we can use the existing image-cache-wrapper. We can update the CACHE_VERSION to 3.

Note on the CDN cache - New Vercel deployments invalidate the CDN cache (see docs here), so it should be safe to cache everything on the CDN without seeing stale content after updates.

---

🚀 Deployment available! Here are the direct links to the updated files:

• https://docs-getdbt-com-git-update-cache-headers-dbt-labs.vercel.app/reference/node-selection/test-selection-examples

TODO

• Remove test content before merge
• Revert image before merge

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Updated (UTC)
docs-getdbt-com	✅ Ready (Inspect)	Visit Preview	Feb 6, 2025 4:46pm

[vercel]

Deployment failed with the following error:

Header at index 1 has invalid `source` pattern "/*.(jpg|png|svg|gif|webp)".

Learn More: https://vercel.link/invalid-route-source-pattern

[vercel]

Deployment failed with the following error:

The `vercel.json` schema validation failed with the following message: `headers[1].headers[0]` should NOT have additional property `_comment`

Learn More: https://vercel.com/docs/concepts/projects/project-configuration

[vercel]

Deployment failed with the following error:

The `vercel.json` schema validation failed with the following message: `headers[0].headers[0]` should NOT have additional property `_comment`

Learn More: https://vercel.com/docs/concepts/projects/project-configuration

[vercel]

Deployment failed with the following error:

Could not parse File as JSON: website/vercel.json

[breezyfasano]

lgtm! verified all images loaded from the memory cache, and did not when 'Disable cache' was disabled woo. Hoping this helps with the overages