[infra] Add script to read builder status from Firestore

This will be used by the new approval workflow to mark a builder
as succeeded or failed (green or red) on the build console, depending
on approvals.

Change-Id: I47bddb1f964d5f5b7c06923660f86f6eb7a5e247
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/125667
Reviewed-by: Jonas Termansen <sortie@google.com>

tools/bots/get_builder_status.dart

@@ -0,0 +1,42 @@
+#!/usr/bin/env dart
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Find the success/failure status for a builder that is written to
+// Firestore by the cloud functions that process results.json.
+// These cloud functions write a success/failure result to the
+// builder table based on the approvals in Firestore.
+
+import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:http/http.dart';
+
+const firebaseUrl =
+    'https://firestore.googleapis.com/v1/projects/dart-ci/databases/(default)/documents';
+
+void main(List<String> args) async {
+  final builder = args[0];
+  final buildNumber = args[1];
+  final client = Client();
+  return; // Temporarily make script return immediately, while we
+  // land recipe change that calls it.
+  for (int count = 0; count < 30; ++count) {
+    // TODO(whesse): Add code to fetch from "try_builds" for builders that
+    // end with "-try".
+    final response =
+        await client.get('$firebaseUrl/build_status/$builder:$buildNumber');
+    if (response.statusCode == HttpStatus.ok) {
+      final document = jsonDecode(response.body);
+      final status = (document['fields']['status'] ?? const {})['stringValue'];
+      if (status == 'success') exit(0);
+      if (status == 'failed') exit(1);
+    }
+    await Future.delayed(Duration(seconds: 10));
+  }
+  print(
+      'No status received for $builder:$buildNumber after 30 attempts, with 10 second waits.');
+  exit(2);
+}