Add gzip compression middleware to API

api/package.json

@@ -29,6 +29,7 @@
     "@types/ws": "^8.18.1",
     "axios": "^1.6.2",
     "bcryptjs": "^2.4.3",
+    "compression": "^1.8.1",
     "cors": "^2.8.5",
     "dotenv": "^16.6.1",
     "express": "^4.18.2",
@@ -44,6 +45,7 @@
   },
   "devDependencies": {
     "@types/bcryptjs": "^2.4.6",
+    "@types/compression": "^1.8.1",
     "@types/cors": "^2.8.17",
     "@types/express": "^4.17.21",
     "@types/jest": "^29.5.11",

api/src/__tests__/compression.test.ts

@@ -0,0 +1,17 @@
+import request from 'supertest';
+import app, { resetRateLimiters } from '../app';
+
+describe('API response compression', () => {
+  beforeEach(async () => {
+    await resetRateLimiters();
+  });
+
+  it('compresses large JSON responses when the client accepts gzip', async () => {
+    const response = await request(app)
+      .get('/api/openapi.json')
+      .set('Accept-Encoding', 'gzip');
+
+    expect(response.status).toBe(200);
+    expect(response.headers['content-encoding']).toBe('gzip');
+  });
+});

api/src/app.ts

@@ -1,6 +1,7 @@
 import express, { Application, Request, Response, NextFunction } from 'express';
 import helmet from 'helmet';
 import cors from 'cors';
+import compression from 'compression';
 import rateLimit, { MemoryStore } from 'express-rate-limit';
 import { config } from './config';
 import { bodySizeLimitMiddleware } from './middleware/bodySizeLimit';
@@ -50,6 +51,7 @@ if (config.server.env === 'production') {
 }
 
 app.use(cors());
+app.use(compression());
 app.use(express.json({ limit: config.bodySizeLimit.limit }));
 app.use(express.urlencoded({ extended: true, limit: config.bodySizeLimit.limit }));
 app.use(sanitizeInput);