如何在flex环境和PHP运行时中使用GAE处理CORS（或任何标题）？

Question

I'm using Google AppEngine with PHP7.2 Runtime and i'm facing a problem with CORS.

With GAE standard environment, it is possible to set headers with app.yaml (handlers.http_headers) cf(https://cloud.google.com/appengine/docs/standard/php/config/appref#handlers_element):

handlers:
- url: /images
  static_dir: static/images
  http_headers:
    X-Foo-Header: foo
    X-Bar-Header: bar value

With GAE flexible environment, it seems that is not possible:

• No handlers.http_headers variable is usable
• Sets Headers directly in the PHP code does not work:

.

$response->headers->add(
    [
        'Access-Control-Allow-Origin' => 'http:/blabla-dot-my-app.appspot.com',
        'Access-Control-Allow-Methods' => 'GET, POST, PUT, DELETE, PATCH, OPTIONS',
    ]
);

It seems that GAE LB is dropping every header we want to set.

So... how to handle CORS (or other headers) with GAE in flexible environment and PHP7.2 runtime ?

Answer 1

Finally, I was the only one faulty on this "issue". The routing defined in dispatch.yaml was set in a way that I was not requesting the right GAE service.

Nevertheless, I've learned that it possible to set headers in two manners:

• Using the code directly:

...

$response->headers->add(
    [
        'Access-Control-Allow-Origin' => '*',
        'Access-Control-Allow-Methods' => 'GET, POST',
        'Access-Control-Allow-Headers' => 'Content-Type,Authorization',
    ]
);

• overriding the nginx configuration used by PHP runtime (cf https://cloud.google.com/appengine/docs/flexible/php/runtime#customizing_nginx):

...

# CORS
add_header 'Access-Control-Allow-Origin' '*';
add_header 'Access-Control-Allow-Methods' 'GET,POST';
add_header 'Access-Control-Allow-Headers' 'Content-Type,Authorization';

location / {
  # CORS (again)
  if ($request_method = 'OPTIONS') {
    add_header 'Access-Control-Allow-Origin' '*';
    add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
    #
    # Tell client that this pre-flight info is valid for 20 days
    #
    add_header 'Access-Control-Max-Age' 1728000;
    add_header 'Content-Type' 'text/plain; charset=utf-8';
    add_header 'Content-Length' 0;
    return 204;
  }
  # try to serve files directly, fallback to the front controller
  try_files $uri /$front_controller_file$is_args$args;
}