Migrating Amazon In-tree to Out-of-tree
Kubernetes is moving away from maintaining cloud providers in-tree. In Kubernetes v1.27 and later, the in-tree cloud providers have been removed. The Rancher UI allows you to upgrade to Kubernetes v1.27 when you migrate from an in-tree to out-of-tree provider.
However, if you're performing a manual migration, existing clusters must upgrade to Kubernetes v1.27 after you migrate in order to remain functional.
To migrate from the in-tree cloud provider to the out-of-tree AWS cloud provider, you must stop the existing cluster's kube controller manager and install the AWS cloud controller manager. There are many ways to do this. Refer to the official AWS documentation on the external cloud controller manager for details.
If it's acceptable to have some downtime during migration, follow the instructions to set up an external cloud provider. These instructions outline how to configure the out-of-tree cloud provider for a newly provisioned cluster. During set up, there will be some downtime, as there is a time gap between when the old cloud provider stops running and when the new cloud provider starts to run.
If your setup can't tolerate any control plane downtime, you must enable leader migration. This facilitates a smooth transition from the controllers in the kube controller manager to their counterparts in the cloud controller manager. Refer to the official AWS documentation on Using leader migration for more details.
The Kubernetes cloud controller migration documentation states that it's possible to migrate with the same Kubernetes version, but assumes that the migration is part of a Kubernetes upgrade. Refer to the Kubernetes documentation on migrating to use the cloud controller manager to see if you need to customize your setup before migrating. Confirm your migration configuration values. If your cloud provider provides an implementation of the Node IPAM controller, you also need to migrate the IPAM controller.
- RKE2
- RKE
- Update the cluster config to enable leader migration:
spec:
rkeConfig:
machineSelectorConfig:
- config:
kube-controller-manager-arg:
- enable-leader-migration
machineLabelSelector:
matchExpressions:
- key: rke.cattle.io/control-plane-role
operator: In
values:
- 'true'
Note that the cloud provider is still aws
at this step:
spec:
rkeConfig:
machineGlobalConfig:
cloud-provider-name: aws
- Cordon control plane nodes so that AWS cloud controller pods run on nodes only after upgrading to the external cloud provider:
kubectl cordon -l "node-role.kubernetes.io/control-plane=true"
- To install the AWS cloud controller manager with leader migration enabled, follow Steps 1-3 for deploying the cloud controller manager chart. From Kubernetes 1.22 onwards, the kube-controller-manager will utilize a default configuration which will satisfy the controller-to-manager migration. Update container args of the
aws-cloud-controller-manager
underspec.rkeConfig.additionalManifest
to enable leader migration:
- '--enable-leader-migration=true'
- Install the chart and confirm that the Daemonset
aws-cloud-controller-manager
successfully deployed:
kubectl rollout status daemonset -n kube-system aws-cloud-controller-manager
- Update the provisioning cluster to change the cloud provider and remove leader migration args from the kube controller.
If upgrading the Kubernetes version, set the Kubernetes version as well in the
spec.kubernetesVersion
section of the cluster YAML file
Only remove cloud-provider-name: aws
if not relying on the rke2 supervisor to correctly set the providerID.
Remove enable-leader-migration
if you don't want it enabled in your cluster:
spec:
rkeConfig:
machineGlobalConfig:
cloud-provider-name: external
Remove enable-leader-migration
from:
spec:
rkeConfig:
machineSelectorConfig:
- config:
kube-controller-manager-arg:
- enable-leader-migration
machineLabelSelector:
matchExpressions:
- key: rke.cattle.io/control-plane-role
operator: In
values:
- 'true'
You can also disable leader migration after the upgrade, as leader migration is no longer required due to only one cloud-controller-manager and can be removed. Upgrade the chart and remove the following section from the container arguments:
- --enable-leader-migration=true
Verify the cloud controller manager update was successfully rolled out with the following command:
kubectl rollout status daemonset -n kube-system aws-cloud-controller-manager
- The cloud provider is responsible for setting the ProviderID of the node. Check if all nodes are initialized with the ProviderID:
kubectl describe nodes | grep "ProviderID"
- Update the cluster config to enable leader migration in
cluster.yml
:
services:
kube-controller:
extra_args:
enable-leader-migration: "true"
Note that the cloud provider is still aws
at this step:
cloud_provider:
name: aws
- Cordon the control plane nodes, so that AWS cloud controller pods run on nodes only after upgrading to the external cloud provider:
kubectl cordon -l "node-role.kubernetes.io/controlplane=true"
- To install the AWS cloud controller manager, you must enable leader migration and follow the same steps as when installing AWS on a new cluster. To enable leader migration, add the following to the container arguments in step 7 while following the steps to install the chart:
- '--enable-leader-migration=true'
Confirm that the chart is installed but that the new pods aren't running yet due to cordoned controlplane nodes. After updating the cluster in the next step, RKE will upgrade and uncordon each node, and schedule
aws-controller-manager
pods.Update
cluster.yml
to change the cloud provider and remove the leader migration arguments from the kube-controller.Selecting External Amazon (out-of-tree) sets
--cloud-provider=external
and lets you enableuseInstanceMetadataHostname
. You must enableuseInstanceMetadataHostname
for node-driver clusters and for custom clusters if not you don't provide a custom node name via--node-name
. EnablinguseInstanceMetadataHostname
will query ec2 metadata service and set/hostname
ashostname-override
forkubelet
andkube-proxy
:
rancher_kubernetes_engine_config:
cloud_provider:
name: external-aws
useInstanceMetadataHostname: true/false
Remove enable-leader-migration
if you don't want it enabled in your cluster:
services:
kube-controller:
extra_args:
enable-leader-migration: "true"
You can also disable leader migration after you finish the migration. Upgrade the chart and remove the following section from the container arguments:
- --enable-leader-migration=true
If you're upgrading the cluster's Kubernetes version, set the Kubernetes version as well.
Update the cluster. The
aws-cloud-controller-manager
pods should now be running.