Does App Platform support SSE (Server-Sent Events) application?

We have a demo SSE server-side app that deployed to the App Platform, yet the client CAN NOT connect to it (Chrome F12 shows “pending” always).

While for other normal endpoints of the same component, it’s OK.

Then we deployed this same code to a droplet, and everything is fine…Connecting to the SSE endpoint will get an HTTP 200.

This is weird, and we don’t know how to handle this trouble.

Any thoughts? Thank you!

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Bobby Iliev
Site Moderator
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April 13, 2023
Accepted Answer

Hey @aaronanemone,

Indeed, the DigitalOcean App Platform may not be well-suited to handle SSE as it is designed to run stateless applications, and SSE relies on maintaining a persistent connection between the server and the client.

As you mentioned, deploying the same code to a Droplet works fine. This suggests that the issue is indeed related to the App Platform’s handling of SSE connections.

Another suggestion here would be to use WebSockets for instead of SSE:

If you still want to use SSE with App Platform, the best thing to do to get your voice heard regarding this would be to head over to our Product Ideas board and post a new idea, including as much information as possible for what you’d like to see implemented.

Hope that helps!

- Bobby.

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’

Same here. Tried implementing SEE with GET requests and didnt’ work. Oddly enough you can make it work with POST requests. No idea why though. If someone knows. Please enlighten me.

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