Configure your clusters to use OpenStack

Google Distributed Cloud software-only supports using OpenStack as a private cloud platform. This guide describes how to configure a cluster to work with an external cloud provider. Running an installation of Google Distributed Cloud software-only clusters on OpenStack lets you use the following OpenStack services:

  • Infrastructure as a Service (IaaS)

  • Load balancing as a Service (LBaaS)

  • Storage

Configuring a cluster to work with OpenStack consists of the following:

  • When you create the cluster, you add a baremetal.cluster.gke.io/external-cloud-provider annotation

  • This annotation causes Google Distributed Cloud to add a kubelet flag cloud-provider=external

  • The kubelet then adds node.cloudprovider.kubernetes.io/uninitialized:NoSchedule taints to the cluster nodes

This configuration allows you and OpenStack to own the node init processes. For example, you can deploy Google Distributed Cloud software on OpenStack to automatically provision OpenStack Load Balancing as a Service (LBaaS) resources or to make use of other OpenStack capabilities. The LBaaS resources can replace the MetalLB resources to expose Services running on your clusters to other OpenStack tenants or outside the OpenStack network. For more information about OpenStack features and benefits, see the OpenStack documentation.

This document only covers how to configure your cluster for use with OpenStack. The following guides walk you through an example deployment:

  • Deploy a cluster on OpenStack walks you through a sample deployment of a hybrid cluster on OpenStack virtual machines (VMs). The deployment uses a script to simplify the installation. The guide also shows you one way to enable load balancing as a Service (LBaaS).

  • Configure the OpenStack Cloud Provider for Kubernetes shows you how to install the OpenStack Cloud Provider on a cluster that's been deployed on OpenStack. The OpenStack Cloud Provider isn't required to use Google Distributed Cloud software with OpenStack.

Before you begin

  • Decide which clusters need to use OpenStack LBaaS resources.

    Once you've created a cluster configured to use OpenStack LBaaS resources, you can't change the configuration to switch to MetalLB resources. Make sure that you initialize your clusters with the correct cloud provider configuration.

  • Ensure you have access to the machines you're trying to configure.

Learn more about running the cloud-controller-manager in the Kubernetes documentation.

Change your cluster configuration file

The OpenStack Kubernetes Cloud Provider requires that kubelet runs on all the nodes with the following argument:

cloud-provider: "external"

To ensure that your cluster meets this requirement, add the baremetal.cluster.gke.io/external-cloud-provider: "true" annotation to your cluster configuration file under the metadata section before you create the cluster.

The entry in your configuration file should look like the following example:

apiVersion: baremetal.cluster.gke.io/v1
kind: Cluster
metadata:
  name: cluster1
  namespace: cluster-cluster1
  annotations:
    baremetal.cluster.gke.io/external-cloud-provider: "true"
spec:
  ...

Some cloud providers on other cloud platforms require a special format for providerID. Google Distributed Cloud generates a providerID with a format like baremetal://MACHINE_ADDRESS for each node machine. If you want to have a different providerID, you can specify one for each node along with the IP address.

The following sample cluster configuration file shows how you specify providerID for your cluster nodes:

 apiVersion: baremetal.cluster.gke.io/v1
 kind: Cluster
 metadata:
   name: cluster1
   namespace: cluster-cluster1
 spec:
   clusterNetwork:
     pods:
       cidrBlocks:
       - 192.168.0.0/16
     services:
       cidrBlocks:
       - 10.96.0.0/20
   controlPlane:
     nodePoolSpec:
       nodes:
       - address: 10.200.0.1
+        providerID: some-prefix://unique-string
       - address: 10.200.0.2
+        providerID: some-prefix2://unique-string2
  ...

---
 apiVersion: baremetal.cluster.gke.io/v1
 kind: NodePool
 metadata:
   name: nodepool1
   namespace: cluster-cluster1
 spec:
   clusterName: cluster1
   nodes:
   - address: 172.18.0.2
+    providerID: some-prefix3://unique-string3

Create your cluster

After you edit the configuration file, use the following command to initialize your cluster:

bmctl create cluster -c cluster1

For more information about creating clusters, see Cluster creation overview.

Node configuration

When you create a cluster configured for OpenStack, the cluster nodes have the following changes:

  • All nodes in cluster1 run with the required argument: cloud-provider: "external".

  • All nodes also have the following taint added to their configuration files:

    taints:
- effect: NoSchedule
  key: node.cloudprovider.kubernetes.io/uninitialized
  value: "true"

    These taints are removed after you initialize your cloud provider on this cluster.

  • kubelet runs with the providerID you specified in the cluster configuration file.

What's next