Check for client cert with exec

[rcanderson23]

Signed-off-by: Carson Anderson rcanderson23@gmail.com

Motivation

Correctly handle client certificates returned with kubeconfig configurations using exec. Current implementation only handles tokens

Solution

This adds Certificate to the Auth enum. The auth is checked when creating the respective TLS configs and uses the certificate if available.

[kazk]

I'm still not sure if this is the right approach, but left some comments.

[rcanderson23]

Thank you for the feedback. If you have other suggestions on you think this should be implemented I am all ears. 😃

[codecov-commenter]

Codecov Report

Merging #1089 (079f460) into main (61f2f32) will decrease coverage by 0.06%.
The diff coverage is 41.66%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1089      +/-   ##
==========================================
- Coverage   72.43%   72.37%   -0.07%     
==========================================
  Files          65       65              
  Lines        4759     4774      +15     
==========================================
+ Hits         3447     3455       +8     
- Misses       1312     1319       +7     

Impacted Files	Coverage Δ
kube-client/src/client/auth/mod.rs	56.38% <0.00%> (+0.33%)	⬆️
kube-client/src/client/config_ext.rs	50.00% <50.00%> (-1.22%)	⬇️

[clux]

I think everything in here has been addressed. A branch update + a just fmt would be appreciated, and I am happy to send it through.

[clux]

Thanks again for figuring this out!

[goenning]

I was about to start working on this, until I synced my fork and noticed this PR was recently merged. Thank you 🎉

---

@rcanderson23 @clux While testing it, I first got this error:

    1: failed to deserialize PEM-encoded chain of certificates: error:0908F066:PEM routines:get_header_and_data:bad end line:crypto/pem/pem_lib.c:856:

It worked on kubectl, but not on kube-rs. After some digging I noticed that PEM-encoded was missing a \n at the end, which seems to be what OpenSSL expects. Apparently Go is a bit more flexible with this and it's ok to not end with a new line. What you think of adding something into kube-rs to handle this?

EDIT: it is a small change so I decided to create a PR to discuss this separately