How to log 500 error/exception from other services?

[tungphuong]

Hello,

I have just used it. It works well but I have one concern that how to log exception (Http code 500) from downstream services. Currently, if I switch log level to "error", I cannot receive anything. However, if log level is "trace", there is some below info

trce: Ocelot.Logging.OcelotDiagnosticListener[0]
      => RequestId:0HLFHAF0APTOQ:00000002 RequestPath:/api/r/xxx/countries => RequestId:0HLFHAF0APTOQ:00000002 RequestPath:/api/r/xxx/countries => RequestId:0HLFHAF0APTOQ:00000002 RequestPath:/api/r/xxx/countries
      requestId: 0HLFHAF0APTOQ:00000002, previousRequestId: no previous request id, message: MiddlewareFinished: Microsoft.AspNetCore.Cors.Infrastructure.CorsMiddleware; 500
: Ocelot.Logging.OcelotDiagnosticListener[0]
      requestId: 0HLFHAF0APTOQ:00000002, previousRequestId: no previous request id, message: MiddlewareFinished: TransitionToOcelotMiddleware; 500

Please let me know if there is any missing.

Thanks,

[TomPallister]

@tungphuong I will test this and get back to you ASAP! If you want to submit a PR that adds the logging let me know.

[TomPallister]

from other issue

Hi,

Currently, if downstream service throw exception with httpcode 500, but Ocelot just logs "warning" or "debug". It will not clear and difficult to trace/monitor on production. Because we cannot set log level is debug/info for production.

I suggest we should check status code. If it is 500, we wil log like error.\

Cheers,

Phuong Le

[tungphuong]

Yes, 2 items are the same. Ok, I will submit one PR :)

[raman-m]

Did you submit a PR?

[raman-m]

5 years have been passed since submission!... 😸

[raman-m]

@tungphuong on Jul 24, 2018

Are you still with Ocelot?
And I don't see Ocelot being forked in your repos...

[ks1990cn]

Interesting, can I replicate on AWS EC2 with cloudwatch? Such that nothing is found on cloudwatch when loglevel set as "Error"?

Can I try replicating issue on this case?

[raman-m]

Tanmay, what's the goal of this discussion?
I've converted old issue to this discussion a month ago having a hope the author will reply with a feedback... Finally, he is silent...
I don't see any sense...
Do you see?

[raman-m]

@tungphuong on Jul 24, 2018:

I have one concern that how to log exception (Http code 500) from downstream services.

Hey Phuong Le!
Seems you are no longer with Ocelot... This is last try to ping you...

What details of 500 error would you like to log by Ocelot?

• Status code and the path
• Status code, template path, service error/exception details

And, why do you think that Ocelot should log error details of downstream service?
I believe downstream should log service errors.

If you want to transfer root cause of 500 error then you have to control downstream service, develop, setup, and prepare error details model to send all this information in response as JSON for example to allow Ocelot to handle this response, detect the case, and log finally by internal Ocelot logger.

Do you understand that you've described invalid user scenario?

---

Currently, if I switch log level to "error", I cannot receive anything.

Right, because Ocelot has internal Error Mapper logic, see the feature docs: Error Status Codes | Design
In case of error 500 on downstream service side Ocelot will recognize it as failed request -> Server error responses

From second side, Error level of Ocelot app means you catch internal Ocelot app exceptions. 500 error of downstream seems doesn't produce internal Ocelot error, the error just remapped with 5xx status but nothing logged.
So, the HttpExceptionToErrorMapper doesn't log anything, simply remapping.
That's why you don't see downstream errors in Ocelot logs!

---

However, if log level is "trace", there is some below info

Exactly, because OcelotDiagnosticListener logs only if Trace level, for debugging purposes. And finally, you realized that you have 500 error case.

---

MiddlewareFinished: Microsoft.AspNetCore.Cors.Infrastructure.CorsMiddleware; 500

Seems the root cause of downstream service failure is invalid CORS policies of the request! Ups! 💥 Bingo!
Setup your request with valid CORS headers to be able being accepted by downstream service!

[raman-m]

Once again, again and again...
Please check direct connection first! If direct connection to downstream service works well, then start write route JSON, and work on route antifactory Ocelot classes.

I don't understand when people says "The app doesn't work. I have a problem".
Please. don't be a lazy developer to check direct connection first! 😠

[raman-m]

How to log 500 error/exception from other services?

Answering the question...
First, you have to send error details in response to the Ocelot's side!
Second, write Delegating Handler to control the route totally analyzing all properties of the response.
Third, your Delegating Handler can be a prototype to process such cases by Ocelot middlewares, and you will be able to create a PR.