feat(aio): add API endpoint for notifying about PR updates

This commit adds an API endpoint for notifying the preview server about PR
updates (`/pr-updated`). According to the update, the preview server can take
several actions. Currently, it will only check and (if necessary) update the
PR's preview visibility (but more actions could be supported in the future).
The API can be used with an automatic trigger (e.g. a GitHub webhook) to
instantly update a PR's preview visibility when it changes.

Fixes #16526

aio/aio-builds-setup/dockerbuild/scripts-js/lib/upload-server/upload-server-factory.ts

@@ -1,4 +1,5 @@
 // Imports
+import * as bodyParser from 'body-parser';
 import * as express from 'express';
 import * as http from 'http';
 import {GithubPullRequests} from '../common/github-pull-requests';
@@ -84,6 +85,7 @@ class UploadServerFactory {
 
   protected createMiddleware(buildVerifier: BuildVerifier, buildCreator: BuildCreator): express.Express {
     const middleware = express();
+    const jsonParser = bodyParser.json();
 
     middleware.get(/^\/create-build\/([1-9][0-9]*)\/([0-9a-f]{40})\/?$/, (req, res) => {
       const pr = req.params[0];
@@ -96,8 +98,8 @@ class UploadServerFactory {
       } else if (!archive) {
         this.throwRequestError(400, `Missing or empty '${X_FILE_HEADER}' header`, req);
       } else {
-        buildVerifier.
-          verify(+pr, authHeader).
+        Promise.resolve().
+          then(() => buildVerifier.verify(+pr, authHeader)).
           then(verStatus => verStatus === BUILD_VERIFICATION_STATUS.verifiedAndTrusted).
           then(isPublic => buildCreator.create(pr, sha, archive, isPublic).
             then(() => res.sendStatus(isPublic ? 201 : 202))).
@@ -105,6 +107,22 @@ class UploadServerFactory {
       }
     });
     middleware.get(/^\/health-check\/?$/, (_req, res) => res.sendStatus(200));
+    middleware.post(/^\/pr-updated\/?$/, jsonParser, (req, res) => {
+      const {action, number: prNo}: {action?: string, number?: number} = req.body;
+      const visMayHaveChanged = !action || (action === 'labeled') || (action === 'unlabeled');
+
+      if (!visMayHaveChanged) {
+        res.sendStatus(200);
+      } else if (!prNo) {
+        this.throwRequestError(400, `Missing or empty 'number' field`, req);
+      } else {
+        Promise.resolve().
+          then(() => buildVerifier.getPrIsTrusted(prNo)).
+          then(isPublic => buildCreator.updatePrVisibility(String(prNo), isPublic)).
+          then(() => res.sendStatus(200)).
+          catch(err => this.respondWithError(res, err));
+      }
+    });
     middleware.all('*', req => this.throwRequestError(404, 'Unknown resource', req));
     middleware.use((err: any, _req: any, res: express.Response, _next: any) => this.respondWithError(res, err));
 
@@ -124,7 +142,10 @@ class UploadServerFactory {
   }
 
   protected throwRequestError(status: number, error: string, req: express.Request) {
-    throw new UploadError(status, `${error} in request: ${req.method} ${req.originalUrl}`);
+    const message = `${error} in request: ${req.method} ${req.originalUrl}` +
+                    (!req.body ? '' : ` ${JSON.stringify(req.body)}`);
+
+    throw new UploadError(status, message);
   }
 }