HTTP response streaming in app platform (for SSE support) | Voters

HTTP response streaming in app platform (for SSE support)

Roger P

I'm trying to serve Server-Sent Events (SSE) using Flask on the DO App Platform, but instead of streaming, something on DO's side seems to be caching the entire response and only returning it in one big chunk. I've been trying and trying to debug, and finally found this page which seems to indicate it's not possible? https://www.digitalocean.com/community/questions/how-to-enable-http-response-streaming-in-the-app-platform

So I have to migrate off the app platform now I guess? Or am I missing something?

May 14, 2023

Shivam Malviya

We are facing the same issue

Pablo Farias

+1, wasted hours until I came across this post. Only POST works for me for SSE.

Anonymous

I am experiencing the same issue with a Python bottle app and GeventServer hosted in app platform - SSE not working

Mikayel Abrahamyan

Hey, it is critical to add support for response streaming in-app platform because nextJs suspense, loading.js/ts not working in the app platform

Daniel Weinmann

+1
This is also really important for Remix/React Router v7 apps. Modern web development relies heavily on streaming.
Are you guys planning on implementing this? I love the App Platform so far and would love to move all my apps from Heroku to DO, but I might have to choose a different provider if you don't implement streaming.

Ronie Martinez

+1
I was trying this with a simple Flask application which worked on a droplet + nginx.
This same app didn't work on App Platform properly.
On initial load, no server response. 
After waiting 3-5 minutes, the data is returned in bulk.
You have to wait the same amount of time until the next set of data is returned.
I am pretty sure that the reverse proxy (looks like cloudflare) is buffering the SSE messages and ignoring the "X-Accel-Buffering=no" header.
Upon searching, I found this related issue: https://github.com/cloudflare/cloudflared/issues/199
I believe CloudFlare caching is enabled. (https://community.cloudflare.com/t/websockets-and-server-side-events-in-my-application-are-not-working-anymore-if-cloudfare-cache-is-enabled/179584/4)
Too bad, I can't move to App Platform yet and keep my Droplet + nginx setup.

Anonymous

Also struggling with this, if anyone has figured a workaround would appreciate the help
EDIT:
Changing my endpoints to accept POST and changing my server response headers as below seems to be working for me for now!
'Content-Type': 'text/event-stream',
'Connection': 'keep-alive',
'Cache-Control': 'no-cache',
'X-Accel-Buffering': 'no'

Alex Cavazos

Anonymous Did you get it to work with GET requests?

Pablo Farias

Alex Cavazos did you find a way to make it work?

Alex Cavazos

Pablo Farias Nope, using the triangle co for http streaming

Pablo Farias

Alex Cavazos thanks for your response. I ended up switching to POST request, same headers as the parent comment, and it works.

Saleh Alzahrani

Open AI apps need this

Francesco

Next.js apps don't work properly without this feature enabled. +1

Jesse Garrison

same issue- any updates on a fix?

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