Provisioning an Oracle Kubernetes Engine (OKE) cluster with Rancher

Background

In my post Automated Oracle Container Engine for Kubernetes (OKE) build with Terraform I shared how we can use Terraform to automate the creation of an Oracle Kubernetes Engine (OKE) cluster on Oracle Cloud Infrastructure (OCI).

An alternative, and increasingly popular approach is Rancher, Rancher provides both a Command Line Interface (CLI) and Web UI interfaces, and addresses Container management across many different on-premises and Cloud solutions.

This got me thinking, can we also use the Rancher server to deploy an Oracle Kubernetes Engine (OKE) on Oracle Cloud Infrastructure (OCI) ?

Rancher Server

The Rancher Server UI is run from docker, so before you start check the Rancher support matrix for OS and Docker versions.

If you don’t have a compatible Virtual Machine (VM) and have VirtualBox and Vagrant installed you may want to consider using my Oracle Linux 8 VM which I made available on Github https://github.com/raekins/vagrant-ol8.

The Vagrant build uses Ansible to configure an Oracle Linux 8 with docker-ce (20.10) and other related packages.

Using a Linux VM or the newly created Vagrant Oracle Linux 8 virtual machine start the Rancher Server container.

[vagrant@ol8-vagrant ~]$ cat /etc/oracle-release 
Oracle Linux Server release 8.4

[vagrant@ol8-vagrant ~]$ docker version --format '{{.Server.Version | printf "%.5s" }}'
20.10

[vagrant@ol8-vagrant ~]$ sudo docker run --privileged -d --restart=unless-stopped -p 80:80 -p 443:443 rancher/rancher
Unable to find image 'rancher/rancher:latest' locally
latest: Pulling from rancher/rancher
...

Rancher OKE creation

Point your browser at the Rancher Server UI, for example https://localhost:8443/ and enter and confirm a password for the admin user.

As we will be using Rancher to create an OKE cluster select I want to create or manage multiple clusters.

By default the Rancher server does not include the Oracle Cloud Infrastructure OKE option under With a hosted Kubernetes provider.

We can easily extend the Rancher Server to include OKE by navigating to Tools -> Drivers.

From here select Oracle OKE and click Activate, this will initiate the download of the Oracle OKE Cluster Driver.

Once complete the state will change from Inactive to Active.

Return to the main menu, and click Add Cluster, the Oracle OKE Kubernetes provider should now be listed.

Add Cluster

To deploy an OKE cluster using Rancher you will need the following OCI details:

• Tenancy OCID
• Region
• User OCID
• User fingerprint
• User private key
• Compartment OCID

Enter a name and optional description in the Cluster Name and Description fields.

Open up the OCI Cloud Credentials area and enter Tenancy OCID, User OCID and User fingerprint, select required Region from the pick-list and copy and paste contents of your ~/.oci/oci_api_key.pem into User Private Key.

Authenticate & Configure Cluster

Select Kubernetes Version from pick list, provide Compartment OCID for the compartment to be used and enter Nodes Per AD Count.

A Nodes Per AD Count value of 1 will create a single worker in each of the three Availability Domains within the Region specified.

Configure Virtual Cloud Network

Choose the Virtual Cloud Network (VCN), Quick Create creates 2 public subnets and a private subnet for the worker nodes.

Configure Node Instances

Select Instance Shape and Operating System from the pick-lists, remember not every shape is available in every Region.

I have select VM Standard E3 Flex, as this is a Flex instance the number of OCPUs is required. As, I do not plan to shell into my servers I do not need to provide a public SSH key.

Once ready click Create.

Clusters

You should now be returned to the Clusters page, where can monitor the state of the OKE cluster provision.

Provisioning

If we logon to our Oracle Cloud account and navigate to Developer Services -> Kubernetes Clustes (OKE) we can see the OKE cluster creation has been initiated.

We now need to wait for Rancher to report the OKE cluster as Active.

Once Active, the Name, Provider and number of Nodes defined earlier should be visible.

Oracle Cloud Infrastructure

If we return to OCI and navigate to Developer Services -> Kubernetes Clusters (OKE) we can view the resources created by the Rancher.

Our Rancher initiated OKE Cluster should now be Active.

Node Pool

Following the Node Pool links from the OKE Cluster, we can confirm Kubernetes Version, Shape, Image Name and number of OCPUs assigned.

We can see that the 3 worker nodes have been created in the 3 Availability Domains (ADs) within my Region.

Local Access

If you plan to access the OKE Cluster from your laptop, return to the Cluster page.

From the OCI hamburger menu Developer Services -> Kubernetes Cluster (OKE) and select OKE cluster.

Select Access Cluster and Local Access, following the instructions provided.

1. Confirm OCI CLI has version number higher than 2.24.0, for example

% oci -v
2.26.2

2. Create a directory for the OKE kubeconfigfile

% mkdir -p $HOME/.kube

3. Create kubeconfigfile using the oci ce cluster create-kubeconfig –cluster-id command provided.

% oci ce cluster create-kubeconfig --cluster-id ocid1.cluster.oc1.uk-london-1.xxx --file $HOME/.kube/config --region uk-london-1 --token-version 2.0.0 

4. Set KUBECONFIG to the location of the .kube/config file.

% export KUBECONFIG=$HOME/.kube/config

Kubectl

Now we have our OKE Cluster up and running and configured a kubeconfig we should be able to use kubectl to manage the OKE Cluster.

I am currently using kubectl versions 1.20.8 on my laptop.

% kubectl version --short | awk -Fv '/Server Version: / {print $3}'
1.20.8

Let’s see if we can see our 3 Kubernetes nodes using kubectl get nodes

% kubectl get nodes -o wide
NAME          STATUS   ROLES   AGE    VERSION   INTERNAL-IP   EXTERNAL-IP      OS-IMAGE                  KERNEL-VERSION                    CONTAINER-RUNTIME
10.0.10.154   Ready    node    119s   v1.20.8   10.0.10.154   132.XXX.XXX.59   Oracle Linux Server 7.9   5.4.17-2102.202.5.el7uek.x86_64   cri-o://1.20.2
10.0.10.179   Ready    node    106s   v1.20.8   10.0.10.179   132.XXX.XXX.87   Oracle Linux Server 7.9   5.4.17-2102.202.5.el7uek.x86_64   cri-o://1.20.2
10.0.10.95    Ready    node    69s    v1.20.8   10.0.10.95    132.XXX.XXX.13   Oracle Linux Server 7.9   5.4.17-2102.202.5.el7uek.x86_64   cri-o://1.20.2

Do we have any pods running in the kube-system namespace

% kubectl get pods -n kube-system
NAME                                   READY   STATUS    RESTARTS   AGE
coredns-749d57869-nh897                1/1     Running   0          99m
coredns-749d57869-vx2sj                1/1     Running   0          92m
coredns-749d57869-wz5cl                1/1     Running   0          92m
csi-oci-node-2sgjm                     1/1     Running   0          94m
csi-oci-node-dzd4j                     1/1     Running   1          93m
csi-oci-node-zvtw5                     1/1     Running   1          94m
kube-dns-autoscaler-6cbdf96f6d-gdjw5   1/1     Running   0          99m
kube-flannel-ds-8dzcd                  1/1     Running   1          94m
kube-flannel-ds-qtd8t                  1/1     Running   2          93m
kube-flannel-ds-z47gz                  1/1     Running   2          94m
kube-proxy-9dpx9                       1/1     Running   0          94m
kube-proxy-hx7xh                       1/1     Running   0          93m
kube-proxy-kk9q9                       1/1     Running   0          94m
proxymux-client-5hdnc                  1/1     Running   0          94m
proxymux-client-6mgx9                  1/1     Running   0          93m
proxymux-client-q7qtg                  1/1     Running   0          94m

Also, what storageclasses are available.

% kubectl get sc       
NAME            PROVISIONER                       RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
oci (default)   oracle.com/oci                    Delete          Immediate              false                  96m
oci-bv          blockvolume.csi.oraclecloud.com   Delete          WaitForFirstConsumer   false                  96m

Summary

In this post I have shared how Rancher can be used to provision a Kubernetes cluster on the Oracle Cloud Container Engine for Kubernetes on Oracle Cloud Infrastructure (OCI)

In my next post I will show how we can use Rancher to install Portworx into our OKE cluster.

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