Why nginx SSI instead of edge workers or CDN?

[Janady13]

Three reasons:

1. No vendor lock-in. SSI is a 20-year-old nginx feature that runs on any nginx 1.x+. Edge workers tie you to Cloudflare/Fastly/Akamai pricing and platform-specific runtimes.

2. Latency is local. SSI fetches from localhost:9090 — the sidecar runs on the same machine as nginx. That's a 1ms loopback, not a 50-200ms edge round-trip.

3. Failure mode is graceful. If the sidecar is down, nginx serves the page without the schema. With edge workers, a worker failure can return a 500 to the user.

The trade-off: SSI doesn't work behind a CDN that caches <!--# include --> markers (some CDNs strip them). If you're behind Cloudflare in default mode, SSI gets stripped. Workaround: run the sidecar behind your origin nginx, with a CDN in front configured to NOT cache HTML pages (cache static assets only).

If you want CDN-side schema injection, that's a different architecture — edge workers are appropriate there.