I would like to upgrade kubernetes from 1.5 to a recent version (i installed it with yum install kubernetes-master kubernetes-client ...) but i don't understand how to achieve it.
Is there yum repos to upgrade kubernetes?
Thanks in advance!
As far as I know there is no official (with official I mean supported by the kubernetes team) way of installing kubernetes on any linux distro using system packages.
Centos provides packages for the old 1.5 version on their extra repository, the packages you actually have installed.
I think you best choice is to install another cluster using an officially supported way, such as kops (if you are on AWS) or kubeadm and migrate your services in the new cluster. This way you have a guarantee that you'll be able to upgrade to future releases.
Please note that kubeadm is not production ready
If you want to proceed this way, you can find a list of installation methods at this page: https://kubernetes.io/docs/setup/pick-right-solution/