Add content-type header = application/json for create and update actions

[abonas]

Following PR Split codec from scheme #17922 on k8s server.
kubernetes/kubernetes#17922

Without sending content-type, the requests fail.
cc @simon3z

[simon3z]

@abonas I think that post and put support :content_type in the request. E.g.

rest_client[ns_prefix + resource_name(entity_type)].post(hash.to_json, @headers, :content_type => 'application/json')

It looks just slightly better (because closer to the to_json transformation), but I don't know if it works.
(Not sure if it's worth investigating, up to you)

Should we do something for what format we expect in the response? E.g. passing the Accept: application/json header to be sure to receive json?

[abonas]

@abonas I think that post and put support :content_type in the request. E.g.

rest_client[ns_prefix + resource_name(entity_type)].post(hash.to_json, @headers, :content_type => 'application/json')
It looks just slightly better (because closer to the to_json transformation), but I don't know if it works.
(Not sure if it's worth investigating, up to you)

@simon3z
I thought about it too, saw some examples that use it. What bothered me is that eventually content type is a header, and there is already a headers object passed. Differentiating it can confuse the reader since it will create 2 different ways of passing headers.
Thoughts?

Should we do something for what format we expect in the response? E.g. passing the Accept: application/json header to be sure to receive json?

It does work without passing Accept, and I remember there were some exceptions that were sent in response as text instead of json from k8s server ( a bug, but still...) , so passing Accept can actually prevent the client from getting an exception from the server.
So I tend to say not to send Accept at the moment.

[simon3z]

OK 👍