Add config option for kube-proxy mode to cluster CR

[nikhita]

Fixes #3935

Defaults to ipvs, if not specified.

For older clusters, they are migrated with proxy mode set to iptables
since that was the one used before.

Does this PR introduce a user-facing change?:

The kube-proxy mode (ipvs/iptables) can now be configured. If not specified, it defaults to ipvs.

[nikhita]

 --- FAIL: TestRetagImageForAllVersions (0.71s)
    main_test.go:31: Error calling getImagesForVersion: failed to get images from addons: failed to get images for addon kube-proxy: failed to parse addon templates in ../../../addons/kube-proxy: failed to execute templating on file ../../../addons/kube-proxy/configmap.yaml: template: configmap.yaml:42:21: executing "configmap.yaml" at <.Cluster.Address.ProxyMode>: can't evaluate field ProxyMode in type v1.ClusterAddress
    main_test.go:31: Error calling getImagesForVersion: failed to get images from addons: failed to get images for addon kube-proxy: failed to parse addon templates in ../../../addons/kube-proxy: failed to execute templating on file ../../../addons/kube-proxy/configmap.yaml: template: configmap.yaml:42:21: executing "configmap.yaml" at <.Cluster.Address.ProxyMode>: can't evaluate field ProxyMode in type v1.ClusterAddress
    main_test.go:31: Error calling getImagesForVersion: failed to get images from addons: failed to get images for addon kube-proxy: failed to parse addon templates in ../../../addons/kube-proxy: failed to execute templating on file ../../../addons/kube-proxy/configmap.yaml: template: configmap.yaml:42:21: executing "configmap.yaml" at <.Cluster.Address.ProxyMode>: can't evaluate field ProxyMode in type v1.ClusterAddress
    main_test.go:31: Error calling getImagesForVersion: failed to get images from addons: failed to get images for addon kube-proxy: failed to parse addon templates in ../../../addons/kube-proxy: failed to execute templating on file ../../../addons/kube-proxy/configmap.yaml: template: configmap.yaml:42:21: executing "configmap.yaml" at <.Cluster.Address.ProxyMode>: can't evaluate field ProxyMode in type v1.ClusterAddress 

I'm guessing this part needs to be updated after the PR is merged so the image is updated too:

kubermatic/addons/kube-proxy/configmap.yaml

Line 42 in ad38125

mode: ""

[nikhita]

/assign @alvaroaleman

[alvaroaleman]

@nikhita You also need to set that in addons/kube-proxy/configmap.yaml, else this setting has no effect

[nikhita]

/retest

[nikhita]

/retest

now that the image was actually updated

[alvaroaleman]

@nikhita I think the issue is that the addon references .Cluster.Address.ProxyMode which doesn't exist, its in .Cluster.Spec.ClusterNetwork or sth

[nikhita]

All green! :)

[alvaroaleman]

Just wanna quickly verify this works on all distributions, other than that, lgtm
/test pull-kubermatic-e2e-do-centos-1.15
/test pull-kubermatic-e2e-hetzner-ubuntu-1.15

[alvaroaleman]

/lgtm
/approve

[kubermatic-bot]

LGTM label has been added.

Git tree hash: ef8efaa8f494f3108cb838397d384b58904e26ca

[kubermatic-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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