Nginx compression and caching

Enable gzip or Brotli at Nginx for text responses — often better CPU economics than compressing in Node. Set `gzip_types` explicitly; default may skip `application/json`.

Proxy cache stores responses from upstream using a cache key (scheme, host, URI, optionally args). Use `proxy_cache_bypass` and `proxy_no_cache` for authenticated routes.

					gzip on;
gzip_types application/json application/javascript text/css;
proxy_cache_path /var/cache/nginx levels=1:2 keys_zone=api:10m;

location /api/public/ {
  proxy_cache api;
  proxy_cache_valid 200 5m;
  proxy_cache_key $scheme$host$request_uri;
  add_header X-Cache-Status $upstream_cache_status;
  proxy_pass http://node_upstream;
}
				

`stale` directives serve cached content when upstream errors — define product tolerance for staleness.

On interviews: avoid double compression (upstream already sends Content-Encoding); cache poisoning via unkeyed `Vary`; purge strategy after deploys.

Common pitfalls: caching Set-Cookie responses; ignoring `Cache-Control: private` from upstream; Brotli on tiny payloads.

The trade-off is balancing simplicity, performance, safety, and operability — name which axis you optimized and what cost you accepted.

Checklist:

• Compress at edge for JSON/HTML when upstream is plain.
• Key proxy cache on variants that matter.
• Bypass cache for auth and mutation routes.
• Expose cache status for debugging.