Invalid HTTP status code 0

[vmihailenco]

http.Handler that does not explicitly sets HTTP status code gets following attributes:

status.code - Unknown
status.message - Invalid HTTP status code 0

At least the status message looks wrong because Go uses 200 OK status code when status code is not explicitly set. So the status code is known and is valid.

[Aneurysm9]

Can you provide a minimal repro? I've tried to reproduce with the othttp.Handler and have been unable. Its responseWriterWrapper ensures that the status is set.

I think that the helper in api/standard is correct as 0 is not a valid HTTP status code. Instrumentations should ensure that it is invoked with a valid status code.

[vmihailenco]

https://gist.github.com/vmihailenco/1028b37642cd04ed0222cfe8a3125dbf prints

"StatusCode":2,"StatusMessage":"Invalid HTTP status code 0"

Its responseWriterWrapper ensures that the status is set.

It just records the status code. I don't see how it does anything beyond that.

[Aneurysm9]

It just records the status code. I don't see how it does anything beyond that.

The responseWriterWrapper will ensure that the status code is http.StatusOK if Write() is called before WriteHeader(), in conformance with the http.ResponseWriter interface. Your repro does neither. In that case the rww.statusCode value remains at its zero value since nothing has updated it.

Is there a valid use for an http.Handler that does not call either Write() or WriteHeader() on its provided http.ResponseWriter?

[vmihailenco]

Is there a valid use for an http.Handler that does not call either Write() or WriteHeader() on its provided http.ResponseWriter?

No calls to WriteHeader means WriteHeader(200). What is wrong with that?

[Aneurysm9]

No calls to WriteHeader means WriteHeader(200). What is wrong with that?

I don't think it does. No calls to WriteHeader() before a call to Write() means WriteHeader(200). See the comments on the interface. No calls to either WriteHeader() or Write() is undefined behavior.

I can't think of a valid reason for an HTTP handler to provide zero response to a request, but it was easy to make a change in #908 that may avoid unexpected behavior.

[vmihailenco]

No calls to either WriteHeader() or Write() is undefined behavior.

In my universe it always sends 200 OK.