Ignore cf loop headers (#33)

* fix: ignore cf loop headers

* fix: ignore render-proxy-ttl header

* fix: add references for ignored headers

src/workflow-requests.ts

@@ -164,9 +164,16 @@ export const recreateUserHeaders = (headers: Headers): Headers => {
     const headerLowerCase = header.toLowerCase();
     if (
       !headerLowerCase.startsWith("upstash-workflow-") &&
+      // https://vercel.com/docs/edge-network/headers/request-headers#x-vercel-id
       !headerLowerCase.startsWith("x-vercel-") &&
       !headerLowerCase.startsWith("x-forwarded-") &&
-      headerLowerCase !== "cf-connecting-ip"
+      // https://blog.cloudflare.com/preventing-request-loops-using-cdn-loop/
+      headerLowerCase !== "cf-connecting-ip" &&
+      headerLowerCase !== "cdn-loop" &&
+      headerLowerCase !== "cf-ew-via" &&
+      headerLowerCase !== "cf-ray" &&
+      // For Render https://render.com
+      headerLowerCase !== "render-proxy-ttl"
     ) {
       filteredHeaders.append(header, value);
     }