Improve HTTP responses

[dora-gt]

Currently HTTP endpoints return JSON like:

{"type":"about:blank","title":"Internal Server Error"}
or
{"type":"about:blank","title":"Bad Request"}

This tells nothing for developers and it's hard to assume what's the problem. We need to improve this.

https://interledger.slack.com/archives/CHC51E54J/p1566983918002000

[emschwartz]

It looks like we can use https://github.com/dtolnay/path-to-error along with the error message returned by serde_json to provide a more helpful error message

[dora-gt]

Because the testnet document depends on test.xpring.tech, I'll try to improve this in parallel.

[dora-gt]

memo:

• https://github.com/carllerche/tower-web/issues/28#issuecomment-450699502
• https://tools.ietf.org/html/rfc7807
• https://github.com/sappenin/java-ilpv4-connector/blob/bb156a9ca177b516c8e994a3efe0bb126737266f/connector-accounts/src/main/java/org/interledger/connector/accounts/AccountNotFoundProblem.java

[dora-gt]

I think there are 2 options to implement this.

1. Improve tower-web
   • https://github.com/carllerche/tower-web/blob/master/src/extract/serde.rs#L179-L181
   • While it seems to be a nice approach, defining type might be difficult because it should not be project specific values.
     • We cannot do like this: https://github.com/dora-gt/tower-web/pull/1/files#diff-e286ed1517feec52f3efeff6fa83cbaeR184
     • Should we let it read from a config file?
2. Implement extract trait on our own
   • If we implement on our own, it might be more flexible. We could specify our own types like https://errors.interledger.org/<api>/<error_type>.
   • I haven't dug into this approach yet enough.

If you @interledger-rs/contributors have any opinion, please tell me.

[emschwartz]

I'm in the process of switching everything over to warp (away from tower-web) so I wouldn't focus on implementing this for tower-web.

warp gives you a bit more manual control over error handling so it shouldn't be too difficult to implement once we decide what we want. See how "rejections" are handled here. We can change our own ApiError type to include more details of the error and then change that error handling logic to include more details in the HTTP response body.

[dora-gt]

Ahhh! sorry, I forgot. Yes, we should use warp. Thank you. I'll check the code.

[gakonst]

Closing, our error handling is very nice now