Setting up a High-availability RKE Kubernetes Cluster

This section describes how to install a Kubernetes cluster. This cluster should be dedicated to run only the Rancher server.

As of Rancher v2.5, Rancher can run on any Kubernetes cluster, included hosted Kubernetes solutions such as Amazon EKS. The below instructions represent only one possible way to install Kubernetes.

For systems without direct internet access, refer to Air Gap: Kubernetes install.

Single-node Installation Tip: In a single-node Kubernetes cluster, the Rancher server does not have high availability, which is important for running Rancher in production. However, installing Rancher on a single-node cluster can be useful if you want to save resources by using a single node in the short term, while preserving a high-availability migration path.

To set up a single-node RKE cluster, configure only one node in the cluster.yml . The single node should have all three roles: etcd, controlplane, and worker.

In both single-node setups, Rancher can be installed with Helm on the Kubernetes cluster in the same way that it would be installed on any other cluster.

Installing Kubernetes

Required CLI Tools

Install kubectl, a Kubernetes command-line tool.

Also install RKE, the Rancher Kubernetes Engine, a Kubernetes distribution and command-line tool.

1. Create the cluster configuration file

In this section, you will create a Kubernetes cluster configuration file called rancher-cluster.yml. In a later step, when you set up the cluster with an RKE command, it will use this file to install Kubernetes on your nodes.

Using the sample below as a guide, create the rancher-cluster.yml file. Replace the IP addresses in the nodes list with the IP address or DNS names of the 3 nodes you created.

If your node has public and internal addresses, it is recommended to set the internal_address: so Kubernetes will use it for intra-cluster communication. Some services like AWS EC2 require setting the internal_address: if you want to use self-referencing security groups or firewalls.

RKE will need to connect to each node over SSH, and it will look for a private key in the default location of ~/.ssh/id_rsa. If your private key for a certain node is in a different location than the default, you will also need to configure the ssh_key_path option for that node.

When choosing a Kubernetes version, be sure to first consult the support matrix to find the highest version of Kubernetes that has been validated for your Rancher version.

nodes:
  - address: 165.227.114.63
    internal_address: 172.16.22.12
    user: ubuntu
    role: [controlplane, worker, etcd]
  - address: 165.227.116.167
    internal_address: 172.16.32.37
    user: ubuntu
    role: [controlplane, worker, etcd]
  - address: 165.227.127.226
    internal_address: 172.16.42.73
    user: ubuntu
    role: [controlplane, worker, etcd]

services:
  etcd:
    snapshot: true
    creation: 6h
    retention: 24h

# Required for external TLS termination with
# ingress-nginx v0.22+
ingress:
  provider: nginx
  options:
    use-forwarded-headers: "true"

kubernetes_version: v1.20.15-rancher2-1

Common RKE Nodes Options

Option	Required	Description
address	yes	The public DNS or IP address
user	yes	A user that can run docker commands
role	yes	List of Kubernetes roles assigned to the node
internal_address	no	The private DNS or IP address for internal cluster traffic
ssh_key_path	no	Path to SSH private key used to authenticate to the node (defaults to ~/.ssh/id_rsa)

Advanced Configurations: RKE has many configuration options for customizing the install to suit your specific environment.

Please see the RKE Documentation for the full list of options and capabilities.

For tuning your etcd cluster for larger Rancher installations, see the etcd settings guide.

2. Run RKE

rke up --config ./rancher-cluster.yml

When finished, it should end with the line: Finished building Kubernetes cluster successfully.

3. Test Your Cluster

This section describes how to set up your workspace so that you can interact with this cluster using the kubectl command-line tool.

Assuming you have installed kubectl, you need to place the kubeconfig file in a location where kubectl can reach it. The kubeconfig file contains the credentials necessary to access your cluster with kubectl.

When you ran rke up, RKE should have created a kubeconfig file named kube_config_cluster.yml. This file has the credentials for kubectl and helm.

Note: If you have used a different file name from rancher-cluster.yml, then the kube config file will be named kube_config_<FILE_NAME>.yml.

Move this file to $HOME/.kube/config, or if you are working with multiple Kubernetes clusters, set the KUBECONFIG environmental variable to the path of kube_config_cluster.yml:

export KUBECONFIG=$(pwd)/kube_config_cluster.yml

Test your connectivity with kubectl and see if all your nodes are in Ready state:

kubectl get nodes

NAME                          STATUS    ROLES                      AGE       VERSION
165.227.114.63                Ready     controlplane,etcd,worker   11m       v1.13.5
165.227.116.167               Ready     controlplane,etcd,worker   11m       v1.13.5
165.227.127.226               Ready     controlplane,etcd,worker   11m       v1.13.5

4. Check the Health of Your Cluster Pods

Check that all the required pods and containers are healthy are ready to continue.

• Pods are in Running or Completed state.
• READY column shows all the containers are running (i.e. 3/3) for pods with STATUS Running
• Pods with STATUS Completed are run-once Jobs. For these pods READY should be 0/1.

kubectl get pods --all-namespaces

NAMESPACE       NAME                                      READY     STATUS      RESTARTS   AGE
ingress-nginx   nginx-ingress-controller-tnsn4            1/1       Running     0          30s
ingress-nginx   nginx-ingress-controller-tw2ht            1/1       Running     0          30s
ingress-nginx   nginx-ingress-controller-v874b            1/1       Running     0          30s
kube-system     canal-jp4hz                               3/3       Running     0          30s
kube-system     canal-z2hg8                               3/3       Running     0          30s
kube-system     canal-z6kpw                               3/3       Running     0          30s
kube-system     kube-dns-7588d5b5f5-sf4vh                 3/3       Running     0          30s
kube-system     kube-dns-autoscaler-5db9bbb766-jz2k6      1/1       Running     0          30s
kube-system     metrics-server-97bc649d5-4rl2q            1/1       Running     0          30s
kube-system     rke-ingress-controller-deploy-job-bhzgm   0/1       Completed   0          30s
kube-system     rke-kubedns-addon-deploy-job-gl7t4        0/1       Completed   0          30s
kube-system     rke-metrics-addon-deploy-job-7ljkc        0/1       Completed   0          30s
kube-system     rke-network-plugin-deploy-job-6pbgj       0/1       Completed   0          30s

This confirms that you have successfully installed a Kubernetes cluster that the Rancher server will run on.

5. Save Your Files

Important The files mentioned below are needed to maintain, troubleshoot and upgrade your cluster.

Save a copy of the following files in a secure location:

• rancher-cluster.yml: The RKE cluster configuration file.
• kube_config_cluster.yml: The Kubeconfig file for the cluster, this file contains credentials for full access to the cluster.
• rancher-cluster.rkestate: The Kubernetes Cluster State file, this file contains credentials for full access to the cluster.
  
  The Kubernetes Cluster State file is only created when using RKE v0.2.0 or higher.

Note: The "rancher-cluster" parts of the two latter file names are dependent on how you name the RKE cluster configuration file.

Issues or errors?

See the Troubleshooting page.

Next: Install Rancher