Setup bootstrap-tokens configuration

[kvaps]

Bootstrap tokens configuration consists of 9 manifests:

# helm install foo kvaps/kubernetes --set persistence.enabled=false --set admin.job.enabled=false
# kubectl exec -ti deploy/foo-kubernetes-admin -- sh
# kubeadm init phase bootstrap-token --config /config/kubeadmcfg.yaml --skip-token-print -v 10 2>&1 | sed -n 's/.*Request Body: //p'
{"kind":"Secret","apiVersion":"v1","metadata":{"name":"bootstrap-token-lusbhc","namespace":"kube-system","creationTimestamp":null},"data":{"auth-extra-groups":"c3lzdGVtOmJvb3RzdHJhcHBlcnM6a3ViZWFkbTpkZWZhdWx0LW5vZGUtdG9rZW4=","expiration":"MjAyMC0xMS0xMFQyMToxNjoxNVo=","token-id":"bHVzYmhj","token-secret":"dmsyOGg2b2h4aW9kOGl2eg==","usage-bootstrap-authentication":"dHJ1ZQ==","usage-bootstrap-signing":"dHJ1ZQ=="},"type":"bootstrap.kubernetes.io/token"}
{"kind":"ClusterRole","apiVersion":"rbac.authorization.k8s.io/v1","metadata":{"name":"kubeadm:get-nodes","namespace":"kube-system","creationTimestamp":null},"rules":[{"verbs":["get"],"apiGroups":[""],"resources":["nodes"]}]}
{"kind":"ClusterRoleBinding","apiVersion":"rbac.authorization.k8s.io/v1","metadata":{"name":"kubeadm:get-nodes","namespace":"kube-system","creationTimestamp":null},"subjects":[{"kind":"Group","name":"system:bootstrappers:kubeadm:default-node-token"}],"roleRef":{"apiGroup":"rbac.authorization.k8s.io","kind":"ClusterRole","name":"kubeadm:get-nodes"}}
{"kind":"ClusterRoleBinding","apiVersion":"rbac.authorization.k8s.io/v1","metadata":{"name":"kubeadm:kubelet-bootstrap","creationTimestamp":null},"subjects":[{"kind":"Group","name":"system:bootstrappers:kubeadm:default-node-token"}],"roleRef":{"apiGroup":"rbac.authorization.k8s.io","kind":"ClusterRole","name":"system:node-bootstrapper"}}
{"kind":"ClusterRoleBinding","apiVersion":"rbac.authorization.k8s.io/v1","metadata":{"name":"kubeadm:node-autoapprove-bootstrap","creationTimestamp":null},"subjects":[{"kind":"Group","name":"system:bootstrappers:kubeadm:default-node-token"}],"roleRef":{"apiGroup":"rbac.authorization.k8s.io","kind":"ClusterRole","name":"system:certificates.k8s.io:certificatesigningrequests:nodeclient"}}
{"kind":"ClusterRoleBinding","apiVersion":"rbac.authorization.k8s.io/v1","metadata":{"name":"kubeadm:node-autoapprove-certificate-rotation","creationTimestamp":null},"subjects":[{"kind":"Group","name":"system:nodes"}],"roleRef":{"apiGroup":"rbac.authorization.k8s.io","kind":"ClusterRole","name":"system:certificates.k8s.io:certificatesigningrequests:selfnodeclient"}}
{"kind":"ConfigMap","apiVersion":"v1","metadata":{"name":"cluster-info","namespace":"kube-public","creationTimestamp":null},"data":{"kubeconfig":"apiVersion: v1\nclusters:\n- cluster:\n    certificate-authority: /pki/admin-client/ca.crt\n    server: https://foo-kubernetes-apiserver:6443\n  name: \"\"\ncontexts: null\ncurrent-context: \"\"\nkind: Config\npreferences: {}\nusers: null\n"}}
{"kind":"Role","apiVersion":"rbac.authorization.k8s.io/v1","metadata":{"name":"kubeadm:bootstrap-signer-clusterinfo","namespace":"kube-public","creationTimestamp":null},"rules":[{"verbs":["get"],"apiGroups":[""],"resources":["configmaps"],"resourceNames":["cluster-info"]}]}
{"kind":"RoleBinding","apiVersion":"rbac.authorization.k8s.io/v1","metadata":{"name":"kubeadm:bootstrap-signer-clusterinfo","namespace":"kube-public","creationTimestamp":null},"subjects":[{"kind":"User","name":"system:anonymous"}],"roleRef":{"apiGroup":"rbac.authorization.k8s.io","kind":"Role","name":"kubeadm:bootstrap-signer-clusterinfo"}}

Let's omit the secret and consider the opportunity to convert the rest to templates, parametrize and put into manifests directory

[gecube]

In the original code they are generated not with manifests, but rather with programmatic way: https://github.com/kubernetes/kubernetes/blob/master/cmd/kubeadm/app/phases/bootstraptoken/node/tlsbootstrap.go

It will be very difficult to support updates to tokens as there are no source manifests. Probably it is wiser to leave it as is and use kubeadm. In any case you will need it for generating join tokens...
I'd like to discuss different approach, because we CAN do what you want, but I don't understand the rewrite benefits

[kvaps]

Hi, bootstrap-token phase perform the two things:

• Applying cluster-info configmap and RBAC manifests into cluster
• Generating temporary token: eg executing kubeadm token create (this creates kube-system/bootstrap-token-xxxxxx secret and records a string .data.jws-kubeconfig-xxxxxx into kube-public/cluster-info configmap)

Actually we don't need to generate the token at this time, but the rest manifests are quite static and not changing during the time thus, we can simple template them using Helm. I wanted to replace this part cause we have to apply these manifests every time we update the release, and every time we have a new token generated. That's not a big problem as the temporary tokens are removing by controller-manager after 24 hours, but when you updating your release quite often they might be annoying.

The main reason why I wanted to get rid of any programmatic kubeadm logic is simplicity to inspecting of all applyable manifests.
Ideally the simple rendering of Helm chart using helm template command, should return self-sufficient set of YAML-manifests necessary to set up working Kubernetes control-plane. However, I want to leave support with kubeadm because many tools rely on it. This issue was created for that reason.