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Issues Found - "Gotchas" in the Assignment

🎯 Intentional Issues Identified

1. Database Configuration Issues

Issue 1.1: Wrong Database Type

  • Location: app/beer_catalog/db.py
  • Problem: Using SQLite instead of PostgreSQL
  • Code: engine = create_engine("sqlite:///beers.db", echo=True)
  • Impact: Assignment requires PostgreSQL RDS, but app is configured for SQLite
  • Fix Needed: Configure for PostgreSQL with environment variables

Issue 1.2: Missing Environment Configuration

  • Location: app/beer_catalog/db.py
  • Problem: Hardcoded database connection string
  • Impact: Violates 12-factor app principle #3 (Config)
  • Fix Needed: Use environment variables for database configuration

2. Application Architecture Issues

Issue 2.1: Missing Error Handling

  • Location: app/beer_catalog/app.py
  • Problem: No error handling in API endpoints
  • Lines: 18-22, 25-35
  • Impact: Application will crash on database errors or invalid input
  • Fix Needed: Add proper error handling and validation

Issue 2.2: Session Management Issues

  • Location: app/beer_catalog/app.py
  • Problem: Manual session management without proper cleanup
  • Impact: Potential memory leaks and connection pool exhaustion
  • Fix Needed: Use context managers or dependency injection

Issue 2.3: Missing Input Validation

  • Location: app/beer_catalog/app.py line 27
  • Problem: No validation for required fields or data types
  • Code: beer = Beer(name=data["name"], style=data.get("style"), abv=data.get("abv"))
  • Impact: Application will crash if "name" is missing
  • Fix Needed: Add proper input validation

3. Data Model Issues

Issue 3.1: Wrong Data Type for ABV

  • Location: app/beer_catalog/beer.py line 12
  • Problem: ABV stored as String instead of Float/Decimal
  • Code: abv = Column(String)
  • Impact: Can't perform numerical operations on ABV values
  • Fix Needed: Change to Float or Decimal type

Issue 3.2: Missing Constraints

  • Location: app/beer_catalog/beer.py
  • Problem: No length constraints on String fields
  • Impact: Potential database performance issues and data integrity problems
  • Fix Needed: Add appropriate length constraints

4. Docker Issues

Issue 4.1: Missing Environment Variables

  • Location: docker/Dockerfile
  • Problem: No environment variable configuration for database
  • Impact: Container can't connect to external database
  • Fix Needed: Add environment variable support

Issue 4.2: Security Issue - Running as Root

  • Location: docker/Dockerfile
  • Problem: Container runs as root user
  • Impact: Security vulnerability
  • Fix Needed: Create non-root user

5. Dependencies Issues

Issue 5.1: Missing PostgreSQL Driver

  • Location: app/pyproject.toml
  • Problem: No PostgreSQL driver in dependencies
  • Impact: Can't connect to PostgreSQL database
  • Fix Needed: Add psycopg2-binary or asyncpg

Issue 5.2: Poetry Configuration Mismatch

  • Location: app/pyproject.toml
  • Problem: Poetry package configuration doesn't match actual structure
  • Code: packages = [{include = "app", from = "src"}]
  • Impact: Poetry won't install correctly
  • Fix Needed: Fix package configuration

6. Infrastructure Issues

Issue 6.1: Empty Terraform Configuration

  • Location: terraform/main.tf
  • Problem: File is completely empty
  • Impact: No infrastructure defined
  • Fix Needed: Implement all required AWS resources

Issue 6.2: Missing Required Providers

  • Location: terraform/versions.tf
  • Problem: PostgreSQL provider included but no PostgreSQL resources defined
  • Impact: Unused provider dependency
  • Fix Needed: Either use the provider or remove it

7. Missing Features

Issue 7.1: No Health Check Endpoint

  • Location: app/beer_catalog/app.py
  • Problem: No health check endpoint for load balancer
  • Impact: ECS service won't know if app is healthy
  • Fix Needed: Add /health endpoint

Issue 7.2: No Logging Configuration

  • Location: app/beer_catalog/app.py
  • Problem: No structured logging
  • Impact: Difficult to debug in production
  • Fix Needed: Add proper logging configuration

🚀 Fix Strategy

Priority 1 (Critical for Basic Functionality)

  1. Fix database configuration (SQLite → PostgreSQL)
  2. Add PostgreSQL driver dependency
  3. Implement environment variable configuration
  4. Add basic error handling

Priority 2 (Important for Production)

  1. Fix data types (ABV as Float)
  2. Add input validation
  3. Implement proper session management
  4. Add health check endpoint

Priority 3 (Best Practices)

  1. Fix Docker security (non-root user)
  2. Add logging configuration
  3. Fix Poetry configuration
  4. Add data constraints

Priority 4 (Infrastructure)

  1. Implement Terraform resources
  2. Configure proper IAM roles
  3. Set up security groups
  4. Implement CI/CD pipeline

📝 Notes for Implementation

  • 12-Factor App Compliance: Most issues violate 12-factor app principles
  • SOLID Principles: Current code doesn't follow single responsibility principle
  • Security: Multiple security issues need addressing
  • Scalability: Current design won't scale in production

🎯 Learning Opportunities

These "gotchas" are actually excellent learning opportunities:

  • Database Migration: Learn how to migrate from SQLite to PostgreSQL
  • Environment Configuration: Understand 12-factor app principles
  • Error Handling: Learn proper error handling patterns
  • Security: Understand container and application security
  • Infrastructure as Code: Start from scratch with proper structure

Issue: ECS App Could Not Connect to RDS (Database Connection Refused)

Symptoms:

  • ECS tasks were repeatedly stopping with exit code 1.
  • CloudWatch logs showed:
    • sqlalchemy.exc.OperationalError: (psycopg2.OperationalError) connection to server at "localhost" (127.0.0.1), port 5432 failed: Connection refused
  • Health check endpoint was not responding; app was not running.

Root Cause:

  • The application was trying to connect to a PostgreSQL database at localhost inside the container, but the actual database was running on AWS RDS in a private subnet.
  • The ECS task definition was only passing DB_HOST or missing the correct DATABASE_URL environment variable, so the app defaulted to localhost.

Troubleshooting Steps:

  1. Checked ECS task status:
    • Noticed tasks were stopping quickly after launch.
  2. Enabled CloudWatch logging:
    • Updated ECS task definition to send logs to CloudWatch for easier debugging.
  3. Reviewed CloudWatch logs:
    • Found clear Python stack trace showing connection attempts to localhost.
  4. Reviewed environment variables:
    • Realized the app expected a DATABASE_URL env var, not just DB_HOST.
  5. Checked RDS endpoint and credentials:
    • Confirmed the correct RDS endpoint, username, and password.

Solution:

  • Updated the ECS task definition in Terraform to set the DATABASE_URL environment variable: 
    environment = [
  {
    name  = "DATABASE_URL"
    value = "postgresql://beer_admin:${var.db_password}@${var.db_host}:5432/beer_catalog"
  }
]
  • Added db_host as a Terraform variable and set it to the RDS endpoint.
  • Re-applied Terraform to update the ECS service and task definition.
  • Verified the app was running and healthy by hitting the /health endpoint.

Key Learnings:

  • Always check CloudWatch logs for ECS task failures—they provide detailed error messages.
  • Ensure your app's environment variables match what the code expects (e.g., DATABASE_URL).
  • Use Terraform variables to avoid hardcoding sensitive or environment-specific values.
  • ECS task definition changes require a new revision and service update.