match Leader Migration beta implementation.
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Indeed
@@ -10,7 +10,7 @@ content_type: task
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<!-- overview -->
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{{< feature-state state="alpha" for_k8s_version="v1.21" >}}
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{{< feature-state state="beta" for_k8s_version="v1.22" >}}
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{{< glossary_definition term_id="cloud-controller-manager" length="all" prepend="The cloud-controller-manager is">}}
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@@ -20,7 +20,7 @@ As part of the [cloud provider extraction effort](https://kubernetes.io/blog/201
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Leader Migration provides a mechanism in which HA clusters can safely migrate "cloud specific" controllers between the `kube-controller-manager` and the `cloud-controller-manager` via a shared resource lock between the two components while upgrading the replicated control plane. For a single-node control plane, or if unavailability of controller managers can be tolerated during the upgrade, Leader Migration is not needed and this guide can be ignored.
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Leader Migration is an alpha feature that is disabled by default and it requires `--enable-leader-migration` to be set on controller managers. It can be enabled by setting the feature gate `ControllerManagerLeaderMigration` plus `--enable-leader-migration` on `kube-controller-manager` or `cloud-controller-manager`. Leader Migration only applies during the upgrade and can be safely disabled or left enabled after the upgrade is complete.
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Leader Migration can be enabled by setting `--enable-leader-migration` on `kube-controller-manager` or `cloud-controller-manager`. Leader Migration only applies during the upgrade and can be safely disabled or left enabled after the upgrade is complete.
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This guide walks you through the manual process of upgrading the control plane from `kube-controller-manager` with built-in cloud provider to running both `kube-controller-manager` and `cloud-controller-manager`. If you use a tool to administrator the cluster, please refer to the documentation of the tool and the cloud provider for more details.
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@@ -30,7 +30,7 @@ It is assumed that the control plane is running Kubernetes version N and to be u
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The control plane nodes should run `kube-controller-manager` with Leader Election enabled through `--leader-elect=true`. As of version N, an in-tree cloud privider must be set with `--cloud-provider` flag and `cloud-controller-manager` should not yet be deployed.
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The out-of-tree cloud provider must have built a `cloud-controller-manager` with Leader Migration implmentation. If the cloud provider imports `k8s.io/cloud-provider` and `k8s.io/controller-manager` of version v0.21.0 or later, Leader Migration will be avaliable.
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The out-of-tree cloud provider must have built a `cloud-controller-manager` with Leader Migration implmentation. If the cloud provider imports `k8s.io/cloud-provider` and `k8s.io/controller-manager` of version v0.21.0 or later, Leader Migration will be avaliable. However, for version before v0.22.0, Leader Migration is alpha and requires feature gate `ControllerManagerLeaderMigration` to be enabled.
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This guide assumes that kubelet of each control plane node starts `kube-controller-manager` and `cloud-controller-manager` as static pods defined by their manifests. If the components run in a different setting, please adjust the steps accordingly.
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@@ -52,11 +52,13 @@ Do the same to the `system::leader-locking-cloud-controller-manager` role.
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### Initial Leader Migration configuration
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Leader Migration requires a configuration file representing the state of controller-to-manager assignment. At this moment, with in-tree cloud provider, `kube-controller-manager` runs `route`, `service`, and `cloud-node-lifecycle`. The following example configuration shows the assignment.
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Leader Migration optionally takes a configuration file representing the state of controller-to-manager assignment. At this moment, with in-tree cloud provider, `kube-controller-manager` runs `route`, `service`, and `cloud-node-lifecycle`. The following example configuration shows the assignment.
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Leader Migration can be enabled without a configuration. Please see [Default Configuration](#default-configuration) for details.
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```yaml
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kind: LeaderMigrationConfiguration
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apiVersion: controllermanager.config.k8s.io/v1alpha1
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apiVersion: controllermanager.config.k8s.io/v1beta1
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leaderName: cloud-provider-extraction-migration
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resourceLock: leases
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controllerLeaders:
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@@ -70,7 +72,6 @@ controllerLeaders:
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On each control plane node, save the content to `/etc/leadermigration.conf`, and update the manifest of `kube-controller-manager` so that the file is mounted inside the container at the same location. Also, update the same manifest to add the following arguments:
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- `--feature-gates=ControllerManagerLeaderMigration=true` to enable Leader Migration which is an alpha feature
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- `--enable-leader-migration` to enable Leader Migration on the controller manager
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- `--leader-migration-config=/etc/leadermigration.conf` to set configuration file
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@@ -82,7 +83,7 @@ In version N + 1, the desired state of controller-to-manager assignment can be r
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```yaml
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kind: LeaderMigrationConfiguration
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apiVersion: controllermanager.config.k8s.io/v1alpha1
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apiVersion: controllermanager.config.k8s.io/v1beta1
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leaderName: cloud-provider-extraction-migration
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resourceLock: leases
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controllerLeaders:
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@@ -113,6 +114,13 @@ Now that the control plane has been upgraded to run both `kube-controller-manage
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In a rolling manager, update manifest of `cloud-controller-manager` to unset both `--enable-leader-migration` and `--leader-migration-config=` flag, also remove the mount of `/etc/leadermigration.conf`, and finally remove `/etc/leadermigration.conf`. To re-enable Leader Migration, recreate the configuration file and add its mount and the flags that enable Leader Migration back to `cloud-controller-manager`.
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### Default Configuration
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Starting Kubernetes 1.22, Leader Migration provides a default configuration suitable for the default controller-to-manager assignment.
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The default configuration can be enabled by setting `--enable-leader-migration` but without `--leader-migration-config=`.
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For `kube-controller-manager` and `cloud-controller-manager`, if there are no flags that enable any in-tree cloud provider or change ownership of controllers, the default configuration can be used to avoid manual creation of the configuration file.
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## {{% heading "whatsnext" %}}
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- Read the [Controller Manager Leader Migration](https://github.com/kubernetes/enhancements/tree/master/keps/sig-cloud-provider/2436-controller-manager-leader-migration) enhancement proposal
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