In order to achieve high availability for your application, you need multiple redundancy for both master and worker nodes. This means at least three master nodes and enough worker nodes to comfortably run your entire application at no more than 75% utilisation. If you’re not sure of how Kubernetes defines nodes, please read our guide on the subject before getting started.
Kubernetes version support
Applications running Kubernetes v1.12 or lower do not support the multi-master feature on Cloud 66. If you have deployed an application via Cloud 66 before March 2019, you will need to redeploy your application "with upgrades" and choose to perform a Kubernetes upgrade (note that this will incur significant downtime as your cluster will be recreated). All applications deployed after March 2019 on version v1.13 and above automatically support multi-master clusters.
Adding nodes to an application
To add nodes to an existing application:
- Open the application page from your Dashboard
- Click Application in the left-hand nav
- Click Servers in the sub nav
- Click + Scale up (top right of the main panel)
- Choose whether the new node(s) will be Master(s) or a Worker(s)
- Choose the server size for the new node(s)
- Choose how many new nodes to add
- Click Add Server to provision your new node(s)
Adding multiple nodes simultaneously
You can simultaneously add multiple nodes to a cluster this way, and that each of these will provision a new server with your cloud provider.