Set Up a Single Instance Kubernetes Cluster

Note:

These steps must be run with the root user, unless specified otherwise!
If you choose to use a different CIDR block (that is, other than 10.244.0.0/16 for the --pod-network-cidr= in the kubeadm init command), then also update NO_PROXY and no_proxy with the appropriate value.
- Also make sure to update kube-flannel.yaml with the new value before deploying.
Replace the following with appropriate values:
- ADD-YOUR-INTERNAL-NO-PROXY-LIST
- REPLACE-WITH-YOUR-COMPANY-PROXY-HOST:PORT

Set up the master node

Create a shell script that sets up the necessary environment variables. You can append this to the user’s .bashrc so that it will run at login. You must also configure your proxy settings here if you are behind an HTTP proxy:

## grab my IP address to pass into  kubeadm init, and to add to no_proxy vars
ip_addr=`nslookup $(hostname -f) | grep -m2 Address | tail -n1| awk -F: '{print $2}'| tr -d " "`
export pod_network_cidr="10.244.0.0/16"
export service_cidr="10.96.0.0/12"
export PATH=$PATH:/sbin:/usr/sbin

### Set the proxies
export NO_PROXY=localhost,.svc,127.0.0.0/8,ADD-YOUR-INTERNAL-NO-PROXY-LIST,/var/run/crio/crio.sock,$ip_addr,$pod_network_cidr,$service_cidr
export no_proxy=localhost,.svc,127.0.0.0/8,ADD-YOUR-INTERNAL-NO-PROXY-LIST,/var/run/crio/crio.sock,$ip_addr,$pod_network_cidr,$service_cidr
export http_proxy=http://REPLACE-WITH-YOUR-COMPANY-PROXY-HOST:PORT
export https_proxy=http://REPLACE-WITH-YOUR-COMPANY-PROXY-HOST:PORT
export HTTPS_PROXY=http://REPLACE-WITH-YOUR-COMPANY-PROXY-HOST:PORT
export HTTP_PROXY=http://REPLACE-WITH-YOUR-COMPANY-PROXY-HOST:PORT

Source the script to set up your environment variables:
```
. ~/.bashrc
```

To implement command completion, add the following to the script:

[ -f /usr/share/bash-completion/bash_completion ] && . /usr/share/bash-completion/bash_completion
source <(kubectl completion bash)

Run kubeadm init to create the master node:

kubeadm init \
  --pod-network-cidr=$pod_network_cidr \
  --apiserver-advertise-address=$ip_addr \
  --ignore-preflight-errors=Swap  > /tmp/kubeadm-init.out 2>&1

Log in to the terminal with YOUR_USERID:YOUR_GROUP. Then set up the ~/.bashrc similar to steps 1 to 3 with YOUR_USERID:YOUR_GROUP.

Note:
From now on we will be using YOUR_USERID:YOUR_GROUP to execute any kubectl commands and not root.

Set up YOUR_USERID:YOUR_GROUP to access the Kubernetes cluster:

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

Verify that YOUR_USERID:YOUR_GROUP is set up to access the Kubernetes cluster using the kubectl command:
```
kubectl get nodes
```
Note:

At this step, the node is not in ready state as we have not yet installed the pod network add-on. After the next step, the node will show status as Ready.
Install a pod network add-on (flannel) so that your pods can communicate with each other.
Note:

If you are using a different CIDR block than 10.244.0.0/16, then download and update kube-flannel.yml with the correct CIDR address before deploying into the cluster:
```
wget https://github.com/flannel-io/flannel/releases/download/v0.25.1/kube-flannel.yml
### Update the CIDR address if you are using a CIDR block other than the default 10.244.0.0/16
kubectl apply -f kube-flannel.yml
```

Verify that the master node is in Ready status:

kubectl get nodes

Sample output:

NAME              STATUS      ROLES        AGE   VERSION
mymasternode      Ready    control-plane   12h   v1.27.2

or:

kubectl get pods -n kube-system

Sample output:

NAME                                    READY       STATUS      RESTARTS    AGE
pod/coredns-86c58d9df4-58p9f                1/1         Running         0       3m59s
pod/coredns-86c58d9df4-mzrr5                1/1         Running         0       3m59s
pod/etcd-mymasternode                       1/1         Running         0       3m4s
pod/kube-apiserver-node                     1/1         Running         0       3m21s
pod/kube-controller-manager-mymasternode    1/1         Running         0       3m25s
pod/kube-flannel-ds-6npx4                   1/1         Running         0       49s
pod/kube-proxy-4vsgm                        1/1         Running         0       3m59s
pod/kube-scheduler-mymasternode             1/1         Running         0       2m58s

To schedule pods on the master node, taint the node:
```
kubectl taint nodes --all node-role.kubernetes.io/control-plane-
```
Congratulations! Your Kubernetes cluster environment is ready to deploy your Oracle SOA Suite domain.

Refer to the official documentation to set up a Kubernetes cluster.