SQL Writer

This guide shows you how to build a hybrid cloud scenario using LocalStack and an external PostgreSQL instance. This lab demonstrates how an AWS Lambda retrieves secrets from Secrets Manager and interacts with a database outside the AWS environment.

Prerequisites

Docker installed and running.
Dev Containers extension installed (optional).
Terraform (included in Dev Container).
AWS CLI (included in Dev Container).
DBeaver or any SQL client (to verify results).

How to execute

Setup Environment:
- Dev Container (recommended)
- Manually
Open VS Code in the project folder and execute this command in the Command Palette:
Terminal window
> Dev Containers: Reopen in Container
Terminal window
docker compose up -d

Then configure the AWS CLI:

aws configure set aws_access_key_id test
aws configure set aws_secret_access_key test
aws configure set region us-east-1

Deploy Resources:

python package_lambda.py
terraform init && terraform apply -auto-approve

Run the Example:

aws --endpoint-url=http://localhost:4566 lambda invoke \
    --function-name AddUserFunction \
    --payload '{}' \
    response.json

Validate results

Check using DBeaver: Connect to the local PostgreSQL instance and run the following query:
- Host: localhost.
- Port: 5432.
- Database: mydb.
- User: myuser.
- Password: mypassword.
```
SELECT * FROM users ORDER BY created_at DESC;
```

Check using AWS CLI:

List Lambda Functions:

aws --endpoint-url=http://localhost:4566 lambda list-functions

Check Secrets:

aws --endpoint-url=http://localhost:4566 secretsmanager list-secrets

Clean Up

terraform destroy -auto-approve
docker compose down -v
rm lambda.zip response.json

Troubleshooting

Issue	Solution
Connection Refused	Ensure `host.docker.internal` is reachable from the LocalStack container. For older Docker on Linux, add it to `extra_hosts` in `docker-compose.yml`.
Port Already in Use	Modify the port mappings for `4566` or `5432` in `docker-compose.yml`.