From the documentation:
Cluster add-ons are Services and Replication Controllers (with pods) that are shipped with the Kubernetes binaries and are considered an inherent part of the Kubernetes clusters. [...] On the cluster, the add-ons are kept in /etc/kubernetes/addons on the master node, in yaml files (json is not supported at the moment). [...] users are discouraged to do it on their own - they should rather wait for a new release of Kubernetes that will also contain new versions of add-ons.
My kubernetes setup is running on fedeora and it has been installed via yum. The version is
Client Version: version.Info{Major:"1", Minor:"1+", GitVersion:"v1.1.0-alpha.0.2175+b6f18c7ce08714", GitCommit:"b6f18c7ce08714c8d4f6019463879a164a41750e", GitTreeState:"clean"}
Server Version: version.Info{Major:"1", Minor:"1+", GitVersion:"v1.1.0-alpha.0.2175+b6f18c7ce08714", GitCommit:"b6f18c7ce08714c8d4f6019463879a164a41750e", GitTreeState:"clean"}Strangely, the folder /etc/kubernetes/addons/ does not exist.
I would like to activate the sky-dns addon. I have tried to read all available documentation, but it is still not clear to me:
How do I properly install and activate an addon? Preferably so that it will receive automated updates in future?
First, it isn't clear from the version number what your are actually running. Github shows a v1.1.0-alpha.1 release and a v1.1.0-alpha.0 tag but nothing named v1.1.0-alpha. Also note that neither of those releases were ever marked as "latest" or "released" meaning that they are not suitable for running in production and may contain egregious bugs (they are alpha quality after all). The latest stable release is v1.1.3 if you want to install that instead.
Second, on a bare metal install the cluster add-ons aren't added automatically. If you follow one of the getting started guides, the turn-key solutions will deploy the cluster add-ons automatically. The most important cluster add-on is DNS, and you can follow the manual instructions to get it installed on your cluster.