Open Stack

Hey,

Kevin raised a good point here:

  https://review.openstack.org/17565

Currently attempting to set a host's status to disabled will fail with
400 Bad Request (without any explanatory error message) if you're using
the libvirt driver.

To be clear, this is a PUT request containing a representation of the
desired status for the host and we don't support changing its status.

I proposed changing this to return a 501 Not Implemented with an
explanatory message, but it's not clear that's correct either.

Things to consider:

  - 4xx codes are for client errors - is this a client error? There is 
    no way for a client to know that a cloud supports this without 
    trying it, so it's obviously something we expect clients to do.

  - 400 explicitly states that clients should not retry the request 
    without modifications. That does apply here.

  - 405 Method Not Allowed is only appropriate where a request method 
    isn't allowed. We do support PUT requests on host resources, just 
    not this particular request.

  - 5xx codes "indicate cases in which the server is aware that it has
    erred or is incapable of performing the request". The latter part 
    seems appropriate here.

  - The 501 docs say:

       The server does not support the functionality required to 
       fulfill the request. This is the appropriate response when the
       server does not recognize the request method and is not capable
       of supporting it for any resource. 

    The first sentence makes it seem like 501 is a good fit here. I 
    take the second sentence to be an example of one of cases where 501 
    is appropriate, rather than the only case.


I think I'm still leaning towards 501. Any thoughts?

Cheers,
Mark.