Launching Kubernetes on Existing Custom Nodes

When you create a custom cluster, Rancher uses RKE (the Rancher Kubernetes Engine) to create a Kubernetes cluster in on-prem bare-metal servers, on-prem virtual machines, or in any node hosted by an infrastructure provider.

To use this option you’ll need access to servers you intend to use in your Kubernetes cluster. Provision each server according to the requirements, which includes some hardware specifications and Docker. After you install Docker on each server, you willl also run the command provided in the Rancher UI on each server to turn each one into a Kubernetes node.

This section describes how to set up a custom cluster.

Creating a Cluster with Custom Nodes

Use Existing Nodes - 图1Want to use Windows hosts as Kubernetes workers?

See Configuring Custom Clusters for Windows before you start.

1. Provision a Linux Host

Begin creation of a custom cluster by provisioning a Linux host. Your host can be:

  • A cloud-host virtual machine (VM)
  • An on-prem VM
  • A bare-metal server

If you want to reuse a node from a previous custom cluster, clean the node before using it in a cluster again. If you reuse a node that hasn’t been cleaned, cluster provisioning may fail.

Provision the host according to the installation requirements and the checklist for production-ready clusters.

If you’re using Amazon EC2 as your host and want to use the dual-stack feature, there are additional requirements when provisioning the host.

2. Create the Custom Cluster

  1. Click ☰ > Cluster Management.

  2. On the Clusters page, click Create.

  3. Click Custom.

  4. Enter a Cluster Name.

  5. Use Cluster Configuration section to choose the version of Kubernetes, what network provider will be used and if you want to enable project network isolation. To see more cluster options, click on Show advanced options.

    Use Existing Nodes - 图2Using Windows nodes as Kubernetes workers?

    Use Existing Nodes - 图3Dual-stack on Amazon EC2:

    If you’re using Amazon EC2 as your host and want to use the dual-stack feature, there are additional requirements when configuring RKE.

  6. Click Next.

  7. Use Member Roles to configure user authorization for the cluster. Click Add Member to add users that can access the cluster. Use the Role drop-down to set permissions for each user.

  8. From Node Role, choose the roles that you want filled by a cluster node. You must provision at least one node for each role: etcd, worker, and control plane. All three roles are required for a custom cluster to finish provisioning. For more information on roles, see this section.

Use Existing Nodes - 图4note

  • Using Windows nodes as Kubernetes workers? See this section.
  • Bare-Metal Server Reminder: If you plan on dedicating bare-metal servers to each role, you must provision a bare-metal server for each role (i.e. provision multiple bare-metal servers).

  1. Optional: Click Show advanced options to specify IP address(es) to use when registering the node, override the hostname of the node, or to add labels or taints to the node.

  2. Copy the command displayed on screen to your clipboard.

  3. Log in to your Linux host using your preferred shell, such as PuTTy or a remote Terminal connection. Run the command copied to your clipboard.

Use Existing Nodes - 图5note

Repeat steps 7-10 if you want to dedicate specific hosts to specific node roles. Repeat the steps as many times as needed.

  1. When you finish running the command(s) on your Linux host(s), click Done.

Result:

Your cluster is created and assigned a state of Provisioning. Rancher is standing up your cluster.

You can access your cluster after its state is updated to Active.

Active clusters are assigned two Projects:

  • Default, containing the default namespace
  • System, containing the cattle-system, ingress-nginx, kube-public, and kube-system namespaces

3. Amazon Only: Tag Resources

If you have configured your cluster to use Amazon as Cloud Provider, tag your AWS resources with a cluster ID.

Amazon Documentation: Tagging Your Amazon EC2 Resources

Use Existing Nodes - 图6note

You can use Amazon EC2 instances without configuring a cloud provider in Kubernetes. You only have to configure the cloud provider if you want to use specific Kubernetes cloud provider functionality. For more information, see Kubernetes Cloud Providers

The following resources need to be tagged with a ClusterID:

  • Nodes: All hosts added in Rancher.
  • Subnet: The subnet used for your cluster
  • Security Group: The security group used for your cluster.

Use Existing Nodes - 图7note

Do not tag multiple security groups. Tagging multiple groups generates an error when creating Elastic Load Balancer.

The tag that should be used is:

  1. Key=kubernetes.io/cluster/<CLUSTERID>, Value=owned

<CLUSTERID> can be any string you choose. However, the same string must be used on every resource you tag. Setting the tag value to owned informs the cluster that all resources tagged with the <CLUSTERID> are owned and managed by this cluster.

If you share resources between clusters, you can change the tag to:

  1. Key=kubernetes.io/cluster/CLUSTERID, Value=shared

Optional Next Steps

After creating your cluster, you can access it through the Rancher UI. As a best practice, we recommend setting up these alternate ways of accessing your cluster:

  • Access your cluster with the kubectl CLI: Follow these steps to access clusters with kubectl on your workstation. In this case, you will be authenticated through the Rancher server’s authentication proxy, then Rancher will connect you to the downstream cluster. This method lets you manage the cluster without the Rancher UI.
  • Access your cluster with the kubectl CLI, using the authorized cluster endpoint: Follow these steps to access your cluster with kubectl directly, without authenticating through Rancher. We recommend setting up this alternative method to access your cluster so that in case you can’t connect to Rancher, you can still access the cluster.