While Cloud Storage
is the recommended solution for reading and writing files in App Engine,
if your app only needs to write temporary files, you can use standard
Go 1.11 methods to write files to a directory named /tmp.
All files in this directory are stored in the instance's RAM, therefore writing
to /tmp takes up system memory. In addition, files in the /tmp directory are
only available to the app instance that created the files. When the instance is
deleted, the temporary files are deleted.