feat: allow clients to control delay on any endpoint

[mc0]

Allow clients to control the delay before a response is written (like the existing /delay/{duration} endpoint) for all endpoints via a special _delay query param.

Note: original description was edited, is preserved below for posterity.

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Original issue

I found myself wanting to delay /image/png or /bytes or /jsonl, but rather than add that to each endpoint perhaps if RedirectTo could delay, then it could follow that redirect. This seems like a powerful feature add for a relatively simple change.

Thanks for the tool and site!

[mccutchen]

I have also wondered whether it would make sense to allow adding arbitrary delay to any endpoint.

If we were to add the feature, I think I'd rather do it on a more generic level (e.g. via a special request header or, more practically, via a special query parameter) than by adding it to the /redirect-to endpoint. A delay then followed by a redirect is an interesting idea, but I think it's meaningfully different enough that it doesn't make as a shortcut.

So I'm generally 👍 on the more general feature request here.

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Implementation-wise, I think we need to

• pick some scheme for "control" query params (e.g. _delay, __delay, __httpbin_delay)
• decide whether they should be omitted by endpoints that echo back a JSON representation of the incoming request (e.g. /get, /post, /anything, etc)
  • my current instinct is to serialize them just like all other query params