Hello Everyone,

Today we will be deploying a 3-tier Context Path Based ALB using Terraform in AWS.

Previously I used a simple Application load balancer so this is an upgrade to project2.

Services used are EC2 Instances, VPC, Nat gateway, Internet Gateway, security groups, ACM, Route53, and Application Load balancer

GitHub link:- https://github.com/piya199616/Terrraform-AWS-Project3.git

Project2 link:- https://priyanka-burela.hashnode.dev/deploy-3-tier-ha-application-load-balancer-using-terraform-in-aws

Link for Manual Creation of Route53 with ACM certificate:

https://priyanka-burela.hashnode.dev/aws-certificate-manager-dns-validation

Project Diagram:-

Pre-requisites

1. AWS Account

2. Terraform installed in the local system

3. AWS CLI installed in the Local system

4. Knowledge of AWS and Terraform.

5. You need a Registered Domain in AWS Route53 to implement this use case.

Introduction

• We are going to implement Context Path-based Routing in AWS Application Load Balancer using Terraform.

• To achieve that we are going to implement many series of steps.

• Our core focus in the entire section should be primarily targeted to two things

  • Listener Indexes: https_listener_index = 0

  • Target Group Indexes: target_group_index = 0

• If we are good at understanding these indexes and how to reference them, we are good with handling these multiple context paths or multiple header-based routes or anything from ALB perspective.

• We are going to implement the following using AWS ALB

1. Fixed Response for /* : http://apps.devopseasy.link

2. App1 /app1* goes to App1 EC2 Instances: http://apps.devopseasy.link/app1/index.html

3. App2 /app2* goes to App2 EC2 Instances: http://apps.devopseasy.link/app2/index.html

4. HTTP to HTTPS Redirect

Step-01: Copy all files from previous section

• We are going to copy all files from c1 to c10 from Project2.

• Create new files

  • c6-02-datasource-route53-zone.tf

  • c11-acm-certificatemanager.tf

  • c12-route53-dnsregistration.tf

• Review the files

  • app1-install.sh

  • app2-install.sh

Step-02: c5-05-securitygroup-loadbalancersg.tf

Update load balancer security group to allow port 443

ingress_rules = ["http-80-tcp", "https-443-tcp"]

Step-03: c6-02-datasource-route53-zone.tf

• Define the datasource for Route53 Zone

Step-04: c7-05-ec2instance-private-app2.tf

• Create new EC2 Instances for App2 Application

• Module Name: ec2_private_app2

• Name: "${var.environment}-app2"

• User Data: user_data = file("${path.module}/app2-install.sh")

Step-05: c11-acm-certificatemanager.tf

• Terraform AWS ACM Module

• Create a SAN SSL Certificate using DNS Validation with Route53

• This is required for us with ALB Load Balancer HTTPS Listener to associate SSL certificate to it

Step-05: c11-acm-certificatemanager.tf

• Terraform AWS ACM Module

• Create a SAN SSL Certificate using DNS Validation with Route53

• This is required for us with ALB Load Balancer HTTPS Listener to associate SSL certificate to it

Step-06: c10-02-ALB-application-loadbalancer.tf

• Terraform ALB Module

• Terraform ALB Module - Complete Example

Step-06-01: HTTP to HTTPS Redirect

Step-06-02: Add Target Group app2

Step-06-03: Add HTTPS Listener

1. Associate SSL Certificate ARN

2. Add fixed response for Root Context /*

Step-06-04: Add HTTPS Listener Rules

• Understand about https_listener_index

• Create Rule-1: /app1* should go to App1 EC2 Instances

• Understand about target_group_index

• Create Rule-2: /app2* should go to App2 EC2 Instances

Step-07: c12-route53-dnsregistration.tf

• Route53 Record Resource

Step-08: Execute Terraform Commands

# Terraform Initialize

terraform init

# Terraform Validate

terraform validate

# Terraform Plan

terraform plan

# Terraform Apply

terraform apply -auto-approve

# Verify

Observation:

1. Verify EC2 Instances for App1

2. Verify EC2 Instances for App2

3. Verify Load Balancer SG - Primarily SSL 443 Rule

4. Verify ALB Listener - HTTP:80 - Should contain a redirect from HTTP to HTTPS

5. Verify ALB Listener - HTTPS:443 - Should contain 3 rules

5.1 /app1* to app1-tg

5.2 /app2* to app2-tg

5.3 /* return Fixed response

6. Verify ALB Target Groups App1 and App2, Targets (should be healthy)

5. Verify SSL Certificate (Certificate Manager)

6. Verify Route53 DNS Record

# Test (Domain will be different for you based on your registered domain)

# Note: All the below URLS should redirect from HTTP to HTTPS

1. Fixed Response: http://apps.devopseasy.link

2. App1 Landing Page: http://apps.devopseasy.link/app1/index.html

3. App1 Metadata Page: http://apps.devopseasy.link/app1/metadata.html

4. App2 Landing Page: http://apps.devopseasy.link/app2/index.html

5. App2 Metadata Page: http://apps.devopseasy.link/app2/metadata.html

Step-09: Clean-Up

# Terraform Destroy

terraform destroy -auto-approve

Results:

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Thank you for reading my blog, Hope you found this helpful.

If you need any help then feel free to ping me on Linkedin:

Linkedin Profile:-linkedin.com/in/priyanka-burela