App Engine response buffering causes SSEs to be buffered

[richard-to]

Not technically a bug.

See https://cloud.google.com/appengine/docs/flexible/how-requests-are-handled?tab=python#x-accel-buffering

Apparently this can be disabled if using X-Accel-Buffering=no in the response.

Not really sure yet how to handle this since this is App Engine specific, so not sure we want to set this every time.

We could have a flag / config / env var that disables it (could be too specific)

Alternatively add a way for people to adjust the header response (this could be too broad)

[richard-to]

Maybe a temporary workaround is to use nginx in front of Mesop. Then I believe you can use nginx to modify the response header. I think the main thing is making a Docker image that has both nginx and Mesop installed.

[wwwillchen]

Interesting, good find!

I did a bit of Googling and it looks like this setting isn't App-engine specific and it's from nginx

I'm inclined to just setting X-Accel-Buffering=no in all the (SSE) UI responses.