The CCM/CSI migration is used to migrate your clusters using legacy in-tree
cloud provider (i.e. created without .cloudProvider.external: true)
to external cloud controller managers (CCMs) and CSI drivers. The CCM/CSI
migration process is currently supported only for OpenStack and
vSphere.
This guide provides the context on:
Cloud providers that want to support advanced Kubernetes use cases can implement Kubernetes controller(s) that would connect Kubernetes clusters with their cloud provider platform/API.
There are three common controllers:
In addition, cloud providers can implement controllers for volume operations so that cloud provider’s storage offerings can be used as Kubernetes volumes.
The cloud provider can choose which controllers they want to implement. In other words, they don’t need to implement all those controllers, and they can also implement additional controllers.
In the early days of Kubernetes, those controllers were implemented as part of kube-controller-manager. Those controllers were named as in-tree cloud providers, where the in-tree part was referring to the fact that the code for those controllers was part of the main Kubernetes repository.
This approach worked in the beginning when only very few cloud providers supported Kubernetes. However, as number of providers that support Kubernetes increased, many problems appeared:
Therefore, it has been decided to deprecate and remove in-tree cloud providers in favor of external cloud controller managers and CSI drivers. It’s expected that in-tree cloud providers will be removed latest by Kubernetes 1.26.
External Cloud Controller Manager (CCM) is a set of controllers implemented by cloud providers. Those controllers are not anymore part of the main Kubernetes repository, instead, cloud providers can host them wherever they want. Those controllers also have the same purpose and tasks as in-tree cloud provider controllers. External CCMs are deployed like any other Kubernetes workload (e.g. using Deployments or DaemonSets), however, other control plane components must be configured properly to utilize external CCMs.
However, the controllers for volume operations are not part of the external CCM. Instead, it has been decided to use Container Storage Interface (CSI) for handling volume operations. CSI drivers (or also called plugins) are CSI implementations that are handling all the volume operations, which was originally done by kube-controller-manager. Similar to external CCMs, CSI drivers are also deployed like any other Kubernetes workload.
If you do not have this section in your KubeOneCluster manifest, then you’re running in-tree cloud provider and you need to migrate.
...
cloudProvider:
external: true
...
We recommend migrating as soon as possible if your provider is supported because many in-tree providers are not maintained any longer, so new features and improvements are only added to the external CCMs and CSI drivers.
Make sure to familiarize yourself with requirements for external CCM and CSI drivers. Those requirements are provided by cloud providers and you can usually find them in the repositories for each components:
The migration is done in two phases as described below. Before the migration, you need to update your KubeOneCluster manifest as appropriate.
You must set .cloudProvider.external to true, so KubeOne can deploy
external CCM and CSI. For example:
apiVersion: kubeone.io/v1beta1
kind: KubeOneCluster
versions:
kubernetes: 1.22.1
cloudProvider:
openstack: {}
external: true
cloudConfig: |
...
In addition to that, specific cloud providers might require additional configuration.
In general, no addition configuration or changes are needed for OpenStack, but make sure to check the documents linked in the Migration Prerequisites section.
You should be able to use the same cloudConfig for external CCM as you used
before, but make sure to check the documents linked in the Migration
Prerequisites section.
However, the vSphere CSI driver has a different configuration file format then
external CCM, so you have to provide it in your KubeOneCluster manifest similar
to the cloudConfig. The CSI configuration is provided using the csiConfig
field, for example:
apiVersion: kubeone.io/v1beta1
kind: KubeOneCluster
versions:
kubernetes: 1.22.1
cloudProvider:
openstack: {}
external: true
cloudConfig: |
...
csiConfig: |
...
Check out the Create a configuration file with vSphere credentials section of
the vSphere CSI Installation document for more details on
how to create the configuration file. In general, the configuration file can
be similar to the cloudConfig configuration with the following changes:
user and password
instead of secret-name and secret-namespacecluster-id must be set to the name of the vSphere Cluster resourceThe first phase assumes deploying the external CCM and CSI plugin, while leaving in-tree provider enabled. Kubernetes API server and kube-controller-manager are configured to:
The existing worker nodes will continue to use in-tree provider, and that’s why we still leave it enabled on API server and kube-controller-manager. Therefore, all worker nodes managed by machine-controller must be rolled out after phase 1 is complete.
To start the first phase of the migration, run the following command. You’ll
be asked to confirm your intention by typing yes.
kubeone migrate to-ccm-csi --manifest kubeone.yaml -t tf.json
This command might take 5-10 minutes to finish. After it’s done, you need to roll out all your worker nodes managed by machine-controller, so they start using external CCM and CSI.
The Rolling Restart MachineDeploments document describes possible approaches for rotating worker nodes. You can use the following command to rotate all worker nodes at the same time. For additional approaches, please check the document.
forceRestartAnnotations="{\"spec\":{\"template\":{\"metadata\":{\"annotations\":{\"forceRestart\":\"$(date +%s)\"}}}}}"
for md in $(kubectl get machinedeployments -n kube-system --no-headers | awk '{print $1}'); do
kubectl patch machinedeployment -n kube-system $md --type=merge -p $forceRestartAnnotations
done
You can watch the progress by running kubectl get nodes. Make sure that all
worker nodes are rotated before proceeding to the next phase.
The CCM/CSI migration is completed by fully-disabling in-tree provider. To trigger the phase 2, users first need to rotate all their worker nodes managed by machine-controller as described in the previous phase.
After all worker nodes are rotated, you can run the following command to complete the migration:
kubeone migrate to-ccm-csi --complete --manifest kubeone.yaml -t tf.json
This command might take up to 5 minutes to finish. After this command is done, the CCM/CSI migration is fully-completed. Congratulations!
Alternative to the CCM/CSI migration is recreating the cluster from scratch
with .cloudProvider.external enabled from the beginning. While that approach
would give you a fresh cluster, it might be complicated because:
Restoring from a backup in case of recreating the cluster is not an option because that might also restore the old configuration and eventually break the cluster.