How To Add Custom Headers To Google Cloud Endpoints

If you want to add custom response headers to GCE (Google Cloud Endpoints), you’re going to have to do some monkey patching.

import endpoints.util as util

# Note: If someone imports send_wsgi_response before here, the function will NOT be decorated
# and the original function will be used until this bit runs
def add_headers(wsgi_func):
    def wrapper(status, headers, content, start_response, cors_handler=None):
        headers.append(('Some-Header', 'some-value'))
        return wsgi_func(status, headers, content, start_response, cors_handler)
    return wrapper

util.send_wsgi_response = add_headers(util.send_wsgi_response)

I put this bit in my that takes care of loading up the service, since I want to make sure this runs first. This is specific example for my needs, so customize as you see fit.