laboratori-cloud/.planning/phases/06-lab-05-database-rds/06-RESEARCH.md

Research: Lab 05 - Database & RDS

Objective: Simulate AWS RDS (Relational Database Service) using PostgreSQL in Docker private network.

---

Domain Research

PostgreSQL in Docker

Official Image: postgres:16-alpine

• Lightweight Alpine-based PostgreSQL
• Default port: 5432
• Environment variables for configuration:
  • POSTGRES_DB: Database name
  • POSTGRES_USER: Username
  • POSTGRES_PASSWORD: Password
  • POSTGRES_INITDB_ARGS: Initialization arguments

Healthcheck: pg_isready command

• Tests if PostgreSQL is ready to accept connections
• Returns 0 if ready, non-zero if not ready

RDS Concepts

AWS RDS Features:

• Managed database service
• Deployed in VPC private subnets
• Automated backups (not simulating in lab)
• Multi-AZ deployment (not simulating in lab)
• Resource limits (instance classes)
• Encryption at rest (not simulating in lab)

Instance Classes (for PARALLELISM):

• db.t2.micro: 1 vCPU, 1 GB RAM
• db.t2.small: 1 vCPU, 2 GB RAM
• db.t2.medium: 2 vCPU, 4 GB RAM

Integration with Previous Labs

Lab 01 (IAM): Non-root containers

• PostgreSQL container must NOT run as root

Lab 02 (Network): Private networks

• Database must be in private network
• NO ports exposed on host

Lab 03 (Compute): Resource limits

• PostgreSQL must have CPU/memory limits

Lab 04 (Storage): Named volumes

• Database data must persist in named volume

---

Common Pitfalls

1. Database accessible from host

   • Must NOT expose ports on host
   • Only accessible from containers in same private network

2. Data loss on container restart

   • Must use named volume for data directory
   • Volume must persist across container lifecycle

3. Running as root

   • PostgreSQL image runs as postgres user by default
   • Must verify non-root execution

4. No resource limits

   • Must configure cpus and memory limits
   • Prevents database from consuming all host resources

---

Testing Strategy

RED Phase Tests (Plan 06-01)

1. Database Creation Test

   • Verify container starts successfully
   • Verify database is initialized
   • Verify pg_isready works

2. Private Network Test

   • Verify database is in private network
   • Verify NOT accessible from host
   • Verify accessible from same network

3. Persistence Test

   • Create test data
   • Stop container
   • Start container
   • Verify data still exists

4. Security Test

   • INF-01: Non-root user
   • INF-02: No host port bindings
   • INF-03: Resource limits
   • INF-04: Named volume

GREEN Phase Implementation (Plan 06-03)

• docker-compose.yml with PostgreSQL in private network
• Named volume for data persistence
• Resource limits for CPU/memory
• Healthcheck configuration
• No host port bindings (INF-02)

---

Cloud Parallels (PARA-01/02/03/04)

Local Concept	AWS Equivalent	Parallel
PostgreSQL container	RDS Instance	Managed database
Private network	VPC Private Subnet	Isolated deployment
Named volume	EBS volume	Data persistence
Resource limits	Instance class	Compute allocation
No root access	AWS IAM authentication	Access control
pg_isready	RDS health check	Availability check