Add environment variables to control settings

src/index.ts

@@ -6,8 +6,13 @@ import { InterchangeSystem, InterchangeSystemBuilderArguments } from "./entities
 import { ChapmanApiBasedParkingRepositoryLoader } from "./loaders/parking/ChapmanApiBasedParkingRepositoryLoader";
 import express from "express";
 import { expressMiddleware } from "@as-integrations/express5";
-import { RATE_LIMITS_DISABLED } from "./environment";
-import rateLimit from "express-rate-limit";
+import {
+  RATE_LIMIT_DELAY_AFTER_REQUESTS,
+  RATE_LIMIT_DELAY_MULTIPLIER_MS,
+  RATE_LIMIT_WINDOW_MS,
+  RATE_LIMITS_DISABLED
+} from "./environment";
+import slowDown from "express-slow-down";
 
 const typeDefs = readFileSync("./schema.graphqls", "utf8");
 
@@ -60,12 +65,12 @@ async function main() {
       expressMiddleware(server, options)
     );
   } else {
-    const limiter = rateLimit({
-      windowMs: 60 * 1000, // Every minute
-      limit: 20000,
-      standardHeaders: 'draft-8', // draft-6: `RateLimit-*` headers; draft-7 & draft-8: combined `RateLimit` header
-      legacyHeaders: false, // Disable the `X-RateLimit-*` headers.
-      ipv6Subnet: 60, // Set to 60 or 64 to be less aggressive, or 52 or 48 to be more aggressive
+    const limiter = slowDown({
+      windowMs: RATE_LIMIT_WINDOW_MS,
+      delayAfter: RATE_LIMIT_DELAY_AFTER_REQUESTS,
+      delayMs: (hits) => {
+        return hits * RATE_LIMIT_DELAY_MULTIPLIER_MS;
+      }
     });
     app.use(
       "/",
@@ -75,7 +80,6 @@ async function main() {
     );
   }
 
-
   const port = process.env.PORT ? parseInt(process.env.PORT) : 4000;
   app.listen(port, () => {
     console.log(`Server ready at port ${port}`);