feat(cachePolicy): [INFRA-1290] Add CDN caching for fx proxy recommendations

src/api/desktop/recommendations/index.ts

@@ -1,4 +1,6 @@
 import express, { NextFunction, Request, Response } from 'express';
+import config from '../../../config';
+import CacheControlHandler from '../../lib/cacheControlHandler';
 import ConsumerKeyHandler from '../../../auth/consumerKeyHandler';
 import { GraphQLErrorHandler } from '../../error/graphQLErrorHandler';
 import { handleQueryParameters } from './inputs';
@@ -7,12 +9,14 @@ import Recommendations from '../../../graphql-proxy/recommendations/recommendati
 import { forwardHeadersMiddleware } from '../../../graphql-proxy/lib/client';
 import { RecommendationsQueryVariables } from '../../../generated/graphql/types';
 import { RecommendationsResponse, responseTransformer } from './response';
+
 const router = express.Router();
 
 router.get(
   '/v1/recommendations',
   // request must include a consumer
   ConsumerKeyHandler,
+  CacheControlHandler('public, max-age=1800', config),
   async (req: Request, res: Response, next: NextFunction) => {
     try {
       const variables = handleQueryParameters(req.query);

src/api/desktop/recommendations/recommendations.spec.ts

@@ -11,7 +11,7 @@ import { components } from '../../../generated/openapi/types';
 type Recommendation = components['schemas']['Recommendation'];
 
 /**
- * This covers some happy path testinf ro complete server
+ * This covers some happy path testing for complete server
  * middleware composition. Unit tests still catch the finer
  * details, this just ensures middleware is all working together.
  *
@@ -72,9 +72,11 @@ describe('recommendations API server', () => {
     const res = await request(app)
       .get(`/desktop/v1/recommendations?${params.toString()}`)
       .set(authHeaders)
-      .send();
+      .send()
+      .expect('Cache-control', 'public, max-age=1800'); // assert the Cache-control header is overwritten by the /v1/recommendations route
 
     expect(res.status).toEqual(200);
+
     // response ins json
     const parsedRes = JSON.parse(res.text);
     expect(parsedRes.data?.length).toEqual(1);

src/api/lib/cacheControlHandler.ts

@@ -2,10 +2,6 @@ import { NextFunction, Request, Response } from 'express';
 
 import ConfigFile from '../../config';
 
-// eslint / prettier config cannot cope with functions that return
-// functions like this. Thrashes between 2 states.
-// prettier-ignore
-
 /**
  * Sets the value of the 'Cache-Control' response header for all downstream
  * express handlers.
@@ -18,13 +14,16 @@ import ConfigFile from '../../config';
  *
  * @param cachePolicy string value to set CacheControl response header
  */
-const CacheControlHandler =
-  (cachePolicy: string, config: typeof ConfigFile) =>
-    (req: Request, res: Response, next: NextFunction): void => {
-      if (config.app.environment !== 'development') {
-        res.set('Cache-control', cachePolicy);
-      }
-      return next();
-    };
+const CacheControlHandler = (
+  cachePolicy: string,
+  config: typeof ConfigFile
+) => {
+  return (req: Request, res: Response, next: NextFunction): void => {
+    if (config.app.environment !== 'development') {
+      res.set('Cache-control', cachePolicy);
+    }
+    return next();
+  };
+};
 
 export default CacheControlHandler;