Cloud Controller Manager Administration [page]deterministic
Since cloud providers develop and release at a different pace compared to the Kubernetes project, abstracting the provider-specific code to the `[cloud-controller-manager](#gloss:cloud-controller-manager)` binary allows cloud vendors to evolve independently from the core Kubernetes code.
The `cloud-controller-manager` can be linked to any cloud provider that satisfies [cloudprovider.Interface](https://github.com/kubernetes/cloud-provider/blob/master/cloud.go). For backwards compatibility, the [cloud-controller-manager](https://github.com/kubernetes/kubernetes/tree/master/cmd/cloud-controller-manager) provided in the core Kubernetes project uses the same cloud libraries as `kube-controller-manager`. Cloud providers already supported in Kubernetes core are expected to use the in-tree cloud-controller-manager to transition out of Kubernetes core.
## Administration
### Requirements
Every cloud has their own set of requirements for running their own cloud provider integration, it should not be too different from the requirements when running `kube-controller-manager`. As a general rule of thumb you'll need:
* cloud authentication/authorization: your cloud may require a token or IAM rules to allow access to their APIs * kubernetes authentication/authorization: cloud-controller-manager may need RBAC rules set to speak to the kubernetes apiserver * high availability: like kube-controller-manager, you may want a high available setup for cloud controller manager using leader election (on by default).
### Running cloud-controller-manager
Successfully running cloud-controller-manager requires some changes to your cluster configuration.
* `kubelet` and `kube-controller-manager` must be set according to the user's usage of external CCM. If the user has an external CCM (not the internal cloud controller loops in the Kubernetes Controller Manager), then `--cloud-provider=external` must be specified. Otherwise, it should not be specified.
Keep in mind that setting up your cluster to use cloud controller manager will change your cluster behaviour in a few ways:
* Components that specify `--cloud-provider=external` will add a taint `node.cloudprovider.kubernetes.io/uninitialized` with an effect `NoSchedule` during initialization. This marks the node as needing a second initialization from an external controller before it can be scheduled work. Note that in the event that cloud controller manager is not available, new nodes in the cluster will be left unschedulable. The taint is important since the scheduler may require cloud specific information about nodes such as their region or type (high cpu, gpu, high memory, spot instance, etc). * cloud information about nodes in the cluster will no longer be retrieved using local metadata, but instead all API calls to retrieve node information will go through cloud controller manager. This may mean you can restrict access to your cloud API on the kubelets for better security. For larger clusters you may want to consider if cloud controller manager will hit rate limits since it is now responsible for almost all API calls to your cloud from within the cluster.
The cloud controller manager can implement:
* Node controller - responsible for updating kubernetes nodes using cloud APIs and deleting kubernetes nodes that were deleted on your cloud. * Service controller - responsible for loadbalancers on your cloud against services of type LoadBalancer. * Route controller - responsible for setting up network routes on your cloud * any other features you would like to implement if you are running an out-of-tree provider.
## Examples
If you are using a cloud that is currently supported in Kubernetes core and would like to adopt cloud controller manager, see the [cloud controller manager in kubernetes core](https://github.com/kubernetes/kubernetes/tree/master/cmd/cloud-controller-manager).
For cloud controller managers not in Kubernetes core, you can find the resp …(trimmed)