node-maintenance-operator

Node Maintenance Operator

node-maintenance-operator is an operator generated from the operator-sdk. The purpose of this operator is to watch for new or deleted custom resources called NodeMaintenance which indicate that a node in the cluster should either:

• NodeMaintenance CR created: move node into maintenance, cordon the node - set it as unschedulable and evict the pods (which can be evicted) from that node.
• NodeMaintenance CR deleted: remove pod from maintenance and uncordon the node - set it as schedulable

Note: The current behavior of the operator is to mimic kubectl drain <node name> as performed in Kubevirt - evict all VMs and Pods on a node

Build and run the operator

Before running the operator, the NodeMaintenance CRD must be registered with the Openshift/Kubernetes apiserver:

$ kubectl create -f deploy/crds/kubevirt_v1alpha1_nodemaintenance_crd.yaml

Once this is done, there are two ways to run the operator:

• As a Deployment inside a Openshift/Kubernetes cluster
• As Go program outside a cluster

1. Run as a Deployment inside the cluster

The Deployment manifest is generated at deploy/operator.yaml. Be sure to update the deployment image if there are changes as shown here.

Setup RBAC and deploy the node-maintenance-operator:

$ kubectl create -f deploy/service_account.yaml
$ kubectl create -f deploy/role.yaml
$ kubectl create -f deploy/role_binding.yaml
$ kubectl create -f deploy/operator.yaml

Verify that the node-maintenance-operator is up and running:

$ kubectl get deployment
NAME                     DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
node-maintenance-operator      1         1         1            1           1m

2. Run locally outside the cluster

This method is preferred during development cycle to deploy and test faster.

Set the name of the operator in an environment variable:

export OPERATOR_NAME=node-maintenance-operator

Run the operator locally with the default Kubernetes config file present at $HOME/.kube/config or with specificing kubeconfig via the flag --kubeconfig=<path/to/kubeconfig>:

$ operator-sdk up local --kubeconfig="<path/to/kubeconfig>"

INFO[0000] Running the operator locally.                
INFO[0000] Using namespace default.                     
{"level":"info","ts":1551793839.3308277,"logger":"cmd","msg":"Go Version: go1.11.4"}
{"level":"info","ts":1551793839.3308823,"logger":"cmd","msg":"Go OS/Arch: linux/amd64"}
{"level":"info","ts":1551793839.330899,"logger":"cmd","msg":"Version of operator-sdk: v0.5.0+git"}
...

Setting Node Maintenance

Set Maintenance on - Create a NodeMaintenance CR

To set maintenance on a node a NodeMaintenance CR should be created. A NodeMaintenance CR contains:

• Name: The name of the node which will be put into maintenance
• Reason: the reason for the node maintenance

Create the example NodeMaintenance CR found at deploy/crds/kubevirt_v1alpha1_nodemaintenance_cr.yaml:

$ cat deploy/crds/kubevirt_v1alpha1_nodemaintenance_cr.yaml

apiVersion: kubevirt.io/v1alpha1
kind: NodeMaintenance
metadata:
  name: nodemaintenance-xyz
spec:
  nodeName: node02
  reason: "Test node maintenance"

$ kubectl apply -f deploy/crds/cache_v1alpha1_memcached_cr.yaml
{"level":"info","ts":1551794418.6742408,"logger":"controller_nodemaintenance","msg":"Reconciling NodeMaintenance","Request.Namespace":"default","Request.Name":"node02"}
{"level":"info","ts":1551794418.674294,"logger":"controller_nodemaintenance","msg":"Applying Maintenance mode on Node: node02 with Reason: Test node maintenance","Request.Namespace":"default","Request.Name":"node02"}
{"level":"info","ts":1551783365.7430992,"logger":"controller_nodemaintenance","msg":"WARNING: ignoring DaemonSet-managed Pods: default/local-volume-provisioner-5xft8, kubevirt/disks-images-provider-bxpc5, kubevirt/virt-handler-52kpr, openshift-monitoring/node-exporter-4c9jt, openshift-node/sync-8w5x8, openshift-sdn/ovs-kvz9w, openshift-sdn/sdn-qnjdz\n"}
{"level":"info","ts":1551783365.7471824,"logger":"controller_nodemaintenance","msg":"evicting pod \"virt-operator-5559b7d86f-2wsnz\"\n"}
{"level":"info","ts":1551783365.7472217,"logger":"controller_nodemaintenance","msg":"evicting pod \"cdi-operator-55b47b74b5-9v25c\"\n"}
{"level":"info","ts":1551783365.747241,"logger":"controller_nodemaintenance","msg":"evicting pod \"virt-api-7fcd86776d-652tv\"\n"}
{"level":"info","ts":1551783365.747243,"logger":"controller_nodemaintenance","msg":"evicting pod \"simple-deployment-1-m5qv9\"\n"}
{"level":"info","ts":1551783365.7472336,"logger":"controller_nodemaintenance","msg":"evicting pod \"virt-controller-8987cffb8-29w26\"\n"}
{"level":"info","ts":1551783365.7472618,"logger":"controller_nodemaintenance","msg":"evicting pod \"virt-controller-8987cffb8-jkgwx\"\n"}
{"level":"info","ts":1551783365.747213,"logger":"controller_nodemaintenance","msg":"evicting pod \"cdi-http-import-server-875858fbd-qh425\"\n"}
{"level":"info","ts":1551783365.7472284,"logger":"controller_nodemaintenance","msg":"evicting pod \"cdi-apiserver-76f5c57975-4d68g\"\n"}
{"level":"info","ts":1551783365.7472222,"logger":"controller_nodemaintenance","msg":"evicting pod \"cdi-uploadproxy-5c8cf6d885-gqvf6\"\n"}
{"level":"info","ts":1551783365.7471826,"logger":"controller_nodemaintenance","msg":"evicting pod \"cdi-deployment-7497dbd678-8ddf7\"\n"}
{"level":"info","ts":1551783372.3010166,"logger":"controller_nodemaintenance","msg":"evicted Pod: simple-deployment-1-m5qv9"}
{"level":"info","ts":1551783373.102215,"logger":"controller_nodemaintenance","msg":"evicted Pod: virt-operator-5559b7d86f-2wsnz"}
{"level":"info","ts":1551783373.7016778,"logger":"controller_nodemaintenance","msg":"evicted Pod: virt-controller-8987cffb8-jkgwx"}
{"level":"info","ts":1551783374.301048,"logger":"controller_nodemaintenance","msg":"evicted Pod: cdi-uploadproxy-5c8cf6d885-gqvf6"}
{"level":"info","ts":1551783374.7006464,"logger":"controller_nodemaintenance","msg":"evicted Pod: cdi-apiserver-76f5c57975-4d68g"}
{"level":"info","ts":1551783375.1010072,"logger":"controller_nodemaintenance","msg":"evicted Pod: virt-controller-8987cffb8-29w26"}
{"level":"info","ts":1551783375.3010762,"logger":"controller_nodemaintenance","msg":"evicted Pod: virt-api-7fcd86776d-652tv"}
{"level":"info","ts":1551783375.700461,"logger":"controller_nodemaintenance","msg":"evicted Pod: cdi-operator-55b47b74b5-9v25c"}
{"level":"info","ts":1551783376.8579638,"logger":"controller_nodemaintenance","msg":"evicted Pod: cdi-deployment-7497dbd678-8ddf7"}
{"level":"info","ts":1551783397.8587294,"logger":"controller_nodemaintenance","msg":"evicted Pod: cdi-http-import-server-875858fbd-qh425"}

Set Maintenance off - Delete the NodeMaintenance CR

To remove maintenance from a node a NodeMaintenance CR with the node's name should be deleted.

$ cat deploy/crds/kubevirt_v1alpha1_nodemaintenance_cr.yaml

apiVersion: kubevirt.io/v1alpha1
kind: NodeMaintenance
metadata:
  name: nodemaintenance-xyz
spec:
  nodeName: node02
  reason: "Test node maintenance"

$ kubectl delete -f deploy/crds/cache_v1alpha1_memcached_cr.yaml

{"level":"info","ts":1551794725.0018933,"logger":"controller_nodemaintenance","msg":"Reconciling NodeMaintenance","Request.Namespace":"default","Request.Name":"node02"}
{"level":"info","ts":1551794725.0021605,"logger":"controller_nodemaintenance","msg":"NodeMaintenance Object: default/node02 Deleted ","Request.Namespace":"default","Request.Name":"node02"}
{"level":"info","ts":1551794725.0022023,"logger":"controller_nodemaintenance","msg":"uncordon Node: node02"}

Tests

Running e2e tests:

Local

Run the operator tests locally with the default Kubernetes config file present at $HOME/.kube/config or with specificing kubeconfig via the flag --kubeconfig=<path/to/kubeconfig> and a namespace --namespace=<namespace>:

operator-sdk test local ./test/e2e --kubeconfig=<path/to/kubeconfig> --namespace=<namespace>

Next Steps

• Trigger VM migration
• Handle unremoved pods and daemonsets
• Check where should the operator be deployed (infra pods?)
• Check behavior for storage pods
• Fencing
• Versioning
• Enhance error handling
• Operator integration and packaging