Switch from _ query param to Cache-Control header for cache busting

src/route/wcl/character-parses.ts

@@ -2,6 +2,7 @@ import { FastifyInstance } from "fastify";
 import axios from "axios";
 import * as cache from "../../cache";
 import * as Sentry from "@sentry/node";
+import { shouldSkipCache } from "./common";
 
 // FIXME we cheat on the character parses due to significant changes to the
 // response from WCL. specifically: it is not currently possible to get all
@@ -14,11 +15,11 @@ import * as Sentry from "@sentry/node";
 // change, we just use the v1 API for this call.
 
 type Query = {
-  _?: string;
   includeCombatantInfo?: string;
   metric: string;
   zone: string;
   timeframe?: string;
+  partition?: string;
   game?: "classic" | "retail";
 };
 
@@ -49,7 +50,7 @@ const characterParses = (app: FastifyInstance) => {
     };
     let data;
     const cacheKey = `character-parses-${req.params.region}-${req.params.server}-${req.params.name}`;
-    if (!req.query._) {
+    if (!shouldSkipCache(req)) {
       data = await cache.remember(cacheKey, thunk);
     } else {
       data = await thunk();

src/route/wcl/common.ts

@@ -53,7 +53,7 @@ export async function decompress(data: string): Promise<unknown> {
  * Wrap a request to WCL in a caching & compression layer.
  */
 export function wrapEndpoint<
-  Q extends { translate?: string; _?: string },
+  Q extends { translate?: string },
   P = ReportParams,
 >(
   url: string,
@@ -69,7 +69,7 @@ export function wrapEndpoint<
       )}-${await queryKey(req.query as Q)}`;
 
       try {
-        if ((req.query as Q)._) {
+        if (shouldSkipCache(req)) {
           const data = await thunk(req);
           if (data) {
             cache.set(cacheKey, data, timeout).catch(Sentry.captureException);
@@ -103,3 +103,14 @@ export function wrapEndpoint<
       }
     });
 }
+
+export function shouldSkipCache(req: FastifyRequest): boolean {
+  const cacheControl = req.headers["cache-control"];
+  if (!cacheControl) {
+    return false;
+  }
+
+  return (
+    cacheControl.includes("no-cache") || cacheControl.includes("max-age=0")
+  );
+}