cilium-etcd-operator

README

Important: for CoreDNS users

In order for the TLS certificates between etcd peers to work correctly, a DNS reverse lookup on a pod IP must map back to pod name. If you are using CoreDNS, check the CoreDNS ConfigMap and validate that in-addr.arpa and ip6.arpa are listed as wildcards for the kubernetes block like this:

    kubectl -n kube-system edit cm coredns
    [...]
    apiVersion: v1
    data:
      Corefile: |
        .:53 {
            errors
            health
            kubernetes cluster.local in-addr.arpa ip6.arpa {
              pods insecure
              upstream
              fallthrough in-addr.arpa ip6.arpa
            }
            prometheus :9153
            proxy . /etc/resolv.conf
            cache 30
        }

The contents can look different than the above. The specific configuration that matters is to make sure that in-addr.arpa and ip6.arpa are listed as wildcards next to cluster.local.

You can validate this by looking up a pod IP with the host utility from any pod:

    host 10.60.20.86
    86.20.60.10.in-addr.arpa domain name pointer cilium-etcd-972nprv9dp.cilium-etcd.kube-system.svc.cluster.local.

Deployment

Deploying the cilium-etcd-operator will automatically only create the Kubernetes secret cilium-etcd-secrets if it does not exist. If you have configured Cilium to use an external etcd, it is likely using the same secret name so deploying the cilium-etcd-operator will not overwrite that secret.

If you want to overwrite the certificates every time you restart cilium-etcd-operator set the following environment variable:

        - name: CILIUM_ETCD_OPERATOR_GENERATE_CERTS
          value: "true"

in the cilium-etcd-operator.yaml file and apply your changes with:

kubectl apply -f https://raw.githubusercontent.com/cilium/cilium-etcd-operator/master/cilium-etcd-operator.yaml

(Optional) Deployment with an existing EtcdCluster custom resource

Optionally, since v2.0.6 cilium-etcd-operator has the ability to re-use an existing EtcdCluster deployed by the user. As an example, you can change the sample cilium-cr.yaml to add more functionalities offered by etcd-operator such as affinity or even set tolerations for the etcd pods. The schema of this resource can be found here

First you have to make sure you have the custom resource definition etcdclusters.etcd.database.coreos.com already deployed in your kubernetes cluster. If not, you can deploy with:

kubectl apply -f https://raw.githubusercontent.com/cilium/cilium-etcd-operator/master/etcd-crd.yaml

After that, you can deploy the cilium EtcdCluster custom resource:

kubectl apply -f https://raw.githubusercontent.com/cilium/cilium-etcd-operator/master/cilium-cr.yaml

If you set up the etcdclusters.etcd.database.coreos.com CRD and EtcdCluster CR, you can change the following RBAC of cilium-etcd-operator ClusterRole from:

- apiGroups:
  - apiextensions.k8s.io
  resources:
  - customresourcedefinitions
  verbs:
  - delete
  - get
  - create

to

- apiGroups:
  - apiextensions.k8s.io
  resources:
  - customresourcedefinitions
  verbs:
  - get

Verification

The cilium-etcd-operator will spawn an etcd-operator and create an etcd cluster. This process can take a couple of seconds or minutes. After bootstrap, a 3 node etcd cluster will be up:

kubectl -n kube-system get pods -l etcd_cluster=cilium-etcd
NAME                     READY   STATUS    RESTARTS   AGE
cilium-etcd-8k5czlw95m   1/1     Running   0          21h
cilium-etcd-mdwk9s99r5   1/1     Running   0          28h
cilium-etcd-zm52g4mqfv   1/1     Running   0          28h

It will also have, if they don't exist, created secrets to allow access to the etcd:

kubectl -n kube-system get secret | grep cilium-
cilium-etcd-client-tls                           Opaque                                3      28h
cilium-etcd-peer-tls                             Opaque                                3      28h
cilium-etcd-server-tls                           Opaque                                3      28h
cilium-token-nj9dm                               kubernetes.io/service-account-token   3      28h

Troubleshooting

Check the status of the etcd-operator:

kubectl -n kube-system get pods -l io.cilium/app=etcd-operator
NAME                             READY   STATUS    RESTARTS   AGE
etcd-operator-547c5c7f84-qqr2t   1/1     Running   1          29h

Check the logs of the etcd-operator:

kubectl -n kube-system logs etcd-operator-547c5c7f84-qqr2t
[...]

Check for failing etcd cluster members:

kubectl -n kube-system get pods -l etcd_cluster=cilium-etcd
NAME                     READY   STATUS    RESTARTS   AGE
cilium-etcd-8k5czlw95m   1/1     Running   0          21h
cilium-etcd-mdwk9s99r5   1/1     Running   0          28h
cilium-etcd-zm52g4mqfv   1/1     Running   0          28h

Check the logs of individual etcd cluster member:

kubectl -n kube-system logs cilium-etcd-8k5czlw95m

Termination

Terminating the cilium-etcd-operator will tear down the operator itself but will keep the etcd cluster up an running. To tear down the etcd cluster itself:

kubectl -n kube-system delete etcdclusters.etcd.database.coreos.com cilium-etcd

If you want to clean all state, run the cleanup script:

./cleanup.sh