Apache Ignite on your Kubernetes Cluster Part 2: RBAC Explained

So previously we had a vanilla installation of Apache Ignite on Kubernetes.

You had a cache service running however all you did was installing a helm chart.
In this blog we shall evaluate what is installed and take notes for our futures helm charts.

The first step would be to view the helm chart.

> helm list
NAME        	NAMESPACE	REVISION	UPDATED                             	STATUS  	CHART       	APP VERSION
ignite-cache	default  	1       	2020-03-07 22:23:49.918924 +0000 UTC	deployed	ignite-1.0.1	2.7.6

Now let’s download it

> helm fetch stable/ignite
> tar xvf ignite-1.0.1.tgz
> cd ignite/; ls -R
Chart.yaml	README.md	templates	values.yaml

./templates:
NOTES.txt			account-role.yaml		persistence-storage-class.yaml	service-account.yaml		svc.yaml
_helpers.tpl			configmap.yaml			role-binding.yaml		stateful-set.yaml		wal-storage-class.yaml

Reading through the template files is a bit challenging (well they are tempaltes :P) so we shall just check what was installed through our previous blog.

Let’s get started with the account-role. The cluster role that ignite shall use needs to be able to get/list/watch the pods and the endpoints. It makes sense since there is a need for discovery between the nodes.

> kubectl get ClusterRole ignite-cache -o yaml
kind: ClusterRole
metadata:
  creationTimestamp: 2020-03-07T22:23:50Z
  name: ignite-cache
  resourceVersion: "137525"
  selfLink: /apis/rbac.authorization.k8s.io/v1/clusterroles/ignite-cache
  uid: 0cad0689-2f94-4b74-87bc-b468e2ac78ae
rules:
- apiGroups:
  - ""
  resources:
  - pods
  - endpoints
  verbs:
  - get
  - list
  - watch

In order to use this role you need a service account. A service account is create with a token.

> kubectl get serviceaccount ignite-cache -o yaml
apiVersion: v1
kind: ServiceAccount
metadata:
  creationTimestamp: 2020-03-07T22:23:50Z
  name: ignite-cache
  namespace: default
  resourceVersion: "137524"
  selfLink: /api/v1/namespaces/default/serviceaccounts/ignite-cache
  uid: 7aab67e5-04db-41a8-b73d-e76e34ca1d8e
secrets:
- name: ignite-cache-token-8rln4

Then we have the role binding. We have a new service account called the ignite-cache which has the role ignite-cache.

> kubectl get ClusterRoleBinding ignite-cache -o yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  creationTimestamp: 2020-03-07T22:23:50Z
  name: ignite-cache
  resourceVersion: "137526"
  selfLink: /apis/rbac.authorization.k8s.io/v1/clusterrolebindings/ignite-cache
  uid: 1e180bd1-567f-4979-a278-ba2e420ed482
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: ignite-cache
subjects:
- kind: ServiceAccount
  name: ignite-cache
  namespace: default

It is important for you ignite workloads to use this service account and its token. By doing so they have the permissions to discover the other nodes in your cluster.

The next blog focuses on the configuration.