Multi-Tier Application Deployment in EKS

Prerequisites:

• Terraform installation on your pc

• Kubectl and Minikube installation

• Installing Helm locally on your pc

• Lucid for the architectural diagram

Architectural Diagram

Summary:

Deploying a multi-tier application (WordPress), using EKS (Elastic Kubernetes Service), EFS (Elastic File System), RDS (Relational Database Service) using Terraform and Helm.

1. To deploy a web app using EKS, you set up EKS Cluster.

2. To make the WordPress data and configuration persistent, you need persistent storage. (EFS for this step)

3. WordPress docker image to simulate the WordPress application

4. Relational Database for WordPress.

Terraform Files and Setup

Creating EKS Cluster and EFS Storage:

• The eks.tf uses EKS terraform module to define the EKS cluster by specifying configurations like region, and instance type.
• You can also view the vpc.tf file which has vpc module that contains the appropriate networking settings, like VPC, subnets, security group, and role.

Defining EFS File System

• The efs. tf is used to store the data and configuration for the project permanently.

EFS provisioner uses EFS Storage for creating resources in the EKS cluster.

I set up the efs provisioner using Helm and the file contents are located in the efs-provisioner folder.

Command to setup Helm:

helm init

helm create efs-provisioner
helm package efs-provisioner
helm install efs-provisioner efs-provisioner-0.1.0.tgz

Replace the cluster name with your cluster name created by Terraform.

Since the EKS Cluster will be created in the AWS console, and Helm is installed directly on your PC, for the two to communicate using Kubernetes you need to set up kubeconfig from your terminal

aws eks update-kubeconfig --name <cluster-name> --region <region>
kubectl get pods --all-namespaces
helm package .
helm install efs ./efs-provisioner-0.1.0.tgz --kubeconfig ~/pathtoconfigfile

The command above is used to install Helm Chart called efs using a specific Kubernetes configuration file.

Here's an example of the expected output screenshot:

To use EFS Provisioner in Kubernetes Deployment to dynamically provision EFS Volume, you need a PersisstantVolumeClaim (PVC).

Provisioning the RDS Database

The RDS database instance is used by WordPress.

Running terraform scripts:

• Clone the repo
• Cd to the terraform folder
• Run terraform init, this command initializes the backend which is responsible for storing Terraform state.
• Tfvar allows to separate sensitive values for my case, the environment tag from the main code. Not including it in the Terraform plan and apply the command generates an error

 terraform plan --var-file=tfvars/dev.tfvars &&  terraform apply --var-file=tfvars/dev.tfvars

Setting up Helm for WordPress Deployment

Deployng Wordpress to EKS

• Add helm repo to the environment helm repo add my-repo https://charts.bitnami.com/bitnami

• Installing helm chart for wordpress helm install my-release my-repo/wordpress --set wordpressPassword=password

• After deployment check pods kubectl get pods

• After successful deployment,check the pods and see the status using; kubectl get pods

To access the external WordPress site:

export SERVICE_IP=$(kubectl get svc --namespace default wp-demo-wordpress --include "{{ range (index .status.loadBalancer.ingress 0) }}{{ . }}{{ end }}")
echo "WordPress URL: http://$SERVICE_IP/"
echo "WordPress Admin URL: http://$SERVICE_IP/admin"

Clean Up Steps

• To destroy the nodes

kubectl delete nodes --all

• To delete the storage class created earlier use:

kubectl delete -f efs-storageclass.yaml

• To delete the terraform files

terraform destroy --var-file=tfvars/dev.tfvars

Challenges Faced:

1. Error: While running terraform plan command, kept getting undeclared input variables for the eks.tf file

   Solution: Creating tfvar folder with env variables defined and referencing them while running terraform scripts terraform plan --var-file=tfvars/devtfvars

2. Error: Kubectl get nodes command failed. This resulted from the DNS resolution issue in the network when the API endpoint is not accessible

   Solution: Destroying the previous resources provisioned by Terraform. Recreating them, ensuring the DNS server in the network resolves to the correct hostname

3. Error: Connection to server localhost:8080 was refused did you specify port?

   

   Solution: This occurs when Kubectl has no permission to access the cluster. Once eks has been provisioned by Terraform, you need to set the kubeconfig to communicate to the cluster.

   The command used is:

```
 aws eks --region REGION update-kubeconfig --name CLUSTER_NAME
  kubectl config view
  kubectl get node

4.  **Error**: After while deploying wordpress after installing Helm, pods being in pending state
    ![Helm pending state]()

 **Solution**: dependency issue with the persistant volume and storage class. (Work In progress)

5.   **Error**: Trying to Access the deployed Wordpres site: Page not working

    ![](terraform/templates/screenshots/wordpress%20not%20working.JPG)

  **Solution**: Allowing port 80 on the load balancer (WIP)

## References Used:

* [Deploying application Using Helm in Kuberenetes](https://medium.com/avmconsulting-blog/deploying-applications-using-helm-in-kubernetes-b5c8b609e4b5)
* [Creating AWS VPC for EKS Cluster](https://www.youtube.com/watch?v=nIIxexG7_a8&list=PLiMWaCMwGJXkeBzos8QuUxiYT6j8JYGE5)

* [Pods in pending state](https://sysdig.com/blog/kubernetes-pod-pending-problems/)