Fix busboy + GCF race condition

functions/http/index.js

@@ -166,24 +166,42 @@ exports.uploadFile = (req, res) => {
  fields[fieldname] = val;
  });
 
+ let fileWrites = [];
+
  // This code will process each file uploaded.
  busboy.on('file', (fieldname, file, filename) => {
  // Note: os.tmpdir() points to an in-memory file system on GCF
  // Thus, any files in it must fit in the instance's memory.
  console.log(`Processed file ${filename}`);
  const filepath = path.join(tmpdir, filename);
  uploads[fieldname] = filepath;
- file.pipe(fs.createWriteStream(filepath));
+
+ const writeStream = fs.createWriteStream(filepath);
+ file.pipe(writeStream);
+
+ // File was processed by Busboy; wait for it to be written to disk.
+ const promise = new Promise((resolve, reject) => {
+ file.on('end', () => {
+ writeStream.end();
+ });
+ writeStream.on('finish', resolve);
+ writeStream.on('error', reject);
+ });
+ fileWrites.push(promise);
  });
 
- // This event will be triggered after all uploaded files are saved.
+ // Triggered once all uploaded files are processed by Busboy.
+ // We still need to wait for the disk writes (saves) to complete.
  busboy.on('finish', () => {
- // TODO(developer): Process uploaded files here
- for (const name in uploads) {
- const file = uploads[name];
- fs.unlinkSync(file);
- }
- res.send();
+ Promise.all(fileWrites)
+ .then(() => {
+ // TODO(developer): Process saved files here
+ for (const name in uploads) {
+ const file = uploads[name];
+ fs.unlinkSync(file);
+ }
+ res.send();
+ });
  });
 
  busboy.end(req.rawBody);