TASK 23

📌 Automate Kubernetes Cluster Using Ansible

🔅 Launch ec2-instances on AWS Cloud eg. for master and slave.

🔅 Create roles that will configure master node and slave node separately.

🔅 Launch a WordPress and MySQL database connected to it in the respective slaves.

🔅 Expose the WordPress pod and client able hit the WordPress IP with its respective port.

In our last article, we launched the k8S cluster over AWS using Ansible.
https://www.linkedin.com/posts/saranya-s23_arthtask-19-activity-6787208553674493952-t-vv

Now what we can do is create a role for automating the deployment of pod over K8s cluster.

Requisites:

1. Get epel release software and install
2. Install python3 and python3-pip
3. Upgrade AWS CLI version.

We will need credentials for going to the instance and doing configurations thus, I have stored all credentials in ansible-vault.

In order to launch the pod, we need a Kubernetes client on our computer configured as a client. Also, we need a WordPress image, maybe you create it yourself and deploy or we have wordpress:5.1.1-php7.3-apache.

WordPress uses SQL as a database, thus we require an image of that also: mysql:5.7.

Note: Your WordPress version should be compatible with the SQL version.

To launch pod over K8S we use:

kubectl run <podname> --image=<image_name>

Lets see how we can do this using ansible:

We have used a shell module to execute the commands.

For MySQL pod we are required to pass environment variables:

1. MYSQL_ROOT_PASSWORD
2. MYSQL_DATABASE
3. MYSQL_USER
4. MYSQL_PASSWORD

Once we have launched the pod, we need to expose the WordPress pod in order to access it.

We have to create service resources for this:
A Kubernetes Service is an abstraction layer that defines a logical set of Pods and enables external traffic exposure, load balancing, and service discovery for those Pods.

Although each Pod has a unique IP address, those IPs are not exposed outside the cluster without a Service. Services allow your applications to receive traffic. Services can be exposed in different ways by specifying a type in the ServiceSpec:

• ClusterIP (default) — Exposes the Service on an internal IP in the cluster. This type makes the Service only reachable from within the cluster.
• NodePort — Exposes the Service on the same port of each selected Node in the cluster using NAT. Makes a Service accessible from outside the cluster using <NodeIP>:<NodePort>. Superset of ClusterIP.
• LoadBalancer — Creates an external load balancer in the current cloud (if supported) and assigns a fixed, external IP to the Service. Superset of NodePort.
• ExternalName — Maps the Service to the contents of the externalName field (e.g. foo.bar.example.com), by returning a CNAME record with its value. No proxying of any kind is set up. This type requires v1.7 or higher of kube-dns, or CoreDNS version 0.0.8 or higher.

We will be using NodePort type to expose the pod using service:

Our pod is exposed.

For this page we need a DB endpoint, thus to get the IP of the Mysql pod , we can use:

- name: "Fetching DB IP"
  shell: "kubectl get pod sqldb -o wide"
  register: dbip

This will help to get the IP of the pod.

TASK COMPLETED !!!