Add a /health function for ease of benchmarking (#412)

* Slightly more defensive API endpoints

* Add health endpoint for benchmarking trivial Firebase fns

functions/src/api.ts

@@ -137,11 +137,11 @@ export const validate = <T extends z.ZodTypeAny>(schema: T, val: unknown) => {
 
 export const newEndpoint = (methods: [string], fn: Handler) =>
   functions.runWith({ minInstances: 1 }).https.onRequest(async (req, res) => {
-    await applyCors(req, res, {
-      origin: [CORS_ORIGIN_MANIFOLD, CORS_ORIGIN_LOCALHOST],
-      methods: methods,
-    })
     try {
+      await applyCors(req, res, {
+        origin: [CORS_ORIGIN_MANIFOLD, CORS_ORIGIN_LOCALHOST],
+        methods: methods,
+      })
       if (!methods.includes(req.method)) {
         const allowed = methods.join(', ')
         throw new APIError(405, `This endpoint supports only ${allowed}.`)

functions/src/health.ts

@@ -0,0 +1,11 @@
+import { newEndpoint } from './api'
+
+export const health = newEndpoint(['GET'], async (_req, [user, _]) => {
+  return {
+    message: 'Server is working.',
+    user: {
+      id: user.id,
+      username: user.username,
+    },
+  }
+})

functions/src/index.ts

@@ -3,6 +3,7 @@ import * as admin from 'firebase-admin'
 admin.initializeApp()
 
 // export * from './keep-awake'
+export * from './health'
 export * from './transact'
 export * from './place-bet'
 export * from './resolve-market'