Route Caching

[ascorbic]

Summary

A platform-agnostic route caching API for Astro SSR pages that enables declarative cache control using web standards.

Examples

Basic route caching

---
// src/pages/products/[id].astro
import { getEntry } from 'astro:content';
const product = await getEntry('products', Astro.params.id);
Astro.cache({
  lastModified: product.updatedAt,
  maxAge: 300,  // Cache for 5 minutes
  swr: 3600,    // Stale-while-revalidate for 1 hour
  tags: ['products', `product:${product.id}`]
});
---
<h1>{product.data.name}</h1>
<p>{product.data.description}</p>

Automatic dependency tracking

// src/pages/api/revalidate.ts
import { getLiveEntry } from "astro:content";

export const POST: APIRoute = async ({ cache, request }) => {
  const { id } = await request.json();
  const { entry } = await getLiveEntry("products", id);

  // Invalidate all pages that depend on this entry
  cache.invalidate(entry);

  return Response.json({ ok: true });
};

Links

• Rendered RFC
• Stage 2 Proposal
• Stage 1 Proposal

[wildfiremedia]

I’d like to see a summary of the total cache along with a list of tags, so we can get an idea of what’s being cached or invalidated and catch any tags that might have been missed which allows us to easily debug.

[florian-lefebvre]

I'm not sure that's something for Astro to provide, feels like maybe it should be achievable through the driver platform (eg. cloudflare)?

[wildfiremedia]

Exclusively for self-hosted servers, these metrics (memory, SWR settings, etc.) are provided in JSON format. I think they could be useful for storefronts that need to cache product listings.

Other ideas, can it cache payload in gzipped or brotli? Thinking by 50% or more is worth saving and reduce latency.

[wildfiremedia]

My other thought is that if we could set a max memory limit, it might help prevent the server from starving or running out of memory when a malicious or heavy request comes in. Should it only cache those with HTTP respond code 200?

https://example.com?test=1
https://example.com?test=...
https://example.com?test=1000