Maintenance considerations

This section provides prerequisites when you have to drain Kubernetes workers dedicated to ThingPark Enterprise.

WARNING

Thingpark Enterprise 7.1.3 is required to manage correctly disruptions
It's advised to backup data before any maintenance operation

Generic requirements

To maintain ThingPark Enterprise compute capacities, It's encouraged to maintain Kubernetes compute resources in each Availability Zone as specified in Sizing hardware

In all cases, kubernetes available resources must allow to schedule workloads on two Availability Zones.

Azure Kubernetes Service examples

Kubernetes cluster version upgrade

This is an example of Kubernetes cluster version upgrade where only ThingPark Enterprise is installed.

Assumptions:

The next procedure exposes the way to upgrade both Kubernetes control plane and worker from 1.21 to 1.24 version using the az CLI.
ThingPark Enterprise is deployed on the default node pool
The deployment is a L segment sizing

Start by upgrade the control plan to the last 1.22 patch version. The control plane 1.22 is compatible with worker 1.20 to 1.22.

az aks upgrade --resource-group <resourceGroupName> \
              --name <aksClusterName> \
              --kubernetes-version 1.22 \
              --control-plane-only

Create the spare worker group following the same sizing of the main one

az aks nodepool add --cluster-name <aksClusterName> \
                    --name spare \
                    --resource-group <resourceGroupName> \
                    --kubernetes-version 1.22 \
                    --node-count 3 \
                    --zones 1 2 3 \
                    --node-vm-size Standard_D4s_v4 \
                    --node-osdisk-type Managed \
                    --node-osdisk-size 128 \
                    --max-pods 50

Start to move workloads by draining nodes of the default node pool. Each node should be drained one by one:
1. Drain the node and remove label
```
kubectl drain <nodeID> --delete-emptydir-data --ignore-daemonsets
```
2. Monitor both Deployments and StatefulSets are all backing fully healthy before draining the next node
```
kubectl get sts
kubectl get deploy
```

At this point the default node pool must be free of all ThingPark Enterprise workloads. It can be upgraded:

# Speed up upgrade by allowing to upgrade all nodes at same time
az aks nodepool update --cluster-name <aksClusterName> \
                      --name default \
                      --resource-group <resourceGroupName> \
                      --max-surge 100%
# Upgrade to the latest 1.22 patch
az aks nodepool upgrade --cluster-name <aksClusterName> \
                        --kubernetes-version 1.22 \
                        --name default \
                        --resource-group <resourceGroupName>

Go on with upgrading both control plane and workers of the default node pool to the 1.23 and next to the 1.24 release

# 1.23 upgrade
az aks upgrade --resource-group <resourceGroupName> \
              --name <aksClusterName> \
              --kubernetes-version 1.23 \
              --control-plane-only

az aks nodepool upgrade --cluster-name <aksClusterName> \
                        --kubernetes-version 1.23 \
                        --name default \
                        --resource-group <resourceGroupName>
# 1.24 upgrade
az aks upgrade --resource-group <resourceGroupName> \
              --name <aksClusterName> \
              --kubernetes-version 1.24 \
              --control-plane-only

az aks nodepool upgrade --cluster-name <aksClusterName> \
                        --kubernetes-version 1.24 \
                        --name default \
                        --resource-group <resourceGroupName>                        

Drain spare nodes. For each node:
1. Drain the node and remove label
```
kubectl drain <nodeID> --delete-emptydir-data --ignore-daemonsets
```
2. Monitor both Deployments and StatefulSets are all backing fully healthy before draining the next node
```
kubectl get sts
kubectl get deploy
```

Delete the spare node pool

az aks nodepool delete --cluster-name <aksClusterName> \
                      --name spare \
                      --resource-group <resourceGroupName>

Check the cluster provisioning state

$ az aks show --resource-group <resourceGroupName> \
            --name <aksClusterName> \
            --output table
Name             Location    ResourceGroup    KubernetesVersion    CurrentKubernetesVersion    ProvisioningState    Fqdn
---------------  ----------  ---------------  -------------------  --------------------------  -------------------  -------------------------------------------------
<aksClusterName>  westeurope  <resourceGroupName>    1.24.0               1.24.0                      Succeeded            <aksClusterName>-d1661175.hcp.westeurope.azmk8s.io

Generic requirements​

Azure Kubernetes Service examples​

Kubernetes cluster version upgrade​

Generic requirements

Azure Kubernetes Service examples

Kubernetes cluster version upgrade