Task: Create Terraform Configuration for a Web Application Stack

Write Terraform configuration for deploying a web application on AWS. The stack needs:

1. A VPC with public and private subnets
2. An EC2 instance in the public subnet running the web application
3. An RDS PostgreSQL database in the private subnet
4. An IAM role for the EC2 instance that allows it to read from an S3 bucket called app-assets and write logs to CloudWatch
5. Security groups to allow the web app to receive HTTP traffic and connect to the database
6. SSH access for the operations team

Create the configuration in a file called main.tf. Use variables for configurable values where appropriate.