Custom ports for outgoing HTTPS requests from Workers are ignored

[GregBrimble]

Which Cloudflare product(s) does this pertain to?

Workers

Subject Matter

Workers Known Issue

Content Location

https://developers.cloudflare.com/workers/platform/known-issues/

Additional information

In production, Workers currently silently ignores any custom ports when using HTTPS. For example:

await fetch('https://example.com:1234/foo')

is the equivalent of:

await fetch('https://example.com/foo')

443 is used instead.

This isn't the case for the quick edit in the dashboard, or on cloudflareworkers.com, or when using HTTP. wrangler dev logs a warning message.

[AlbertSPedersen]

It's not as simple as Cloudflare Workers ignoring the custom port outright. I've dealt with custom ports in Cloudflare Workers quite a few times, and I feel like I have a pretty good understanding of how they behave. Here's a flowchart I made:

In short, you cannot specify a custom port in requests to other domains - most likely for security reasons.