week-7: PostgreSQL RDS integration — terraform, backend, pipeline

infra/terraform/ec2.tf

@@ -57,11 +57,17 @@ resource "aws_instance" "app" {
     docker pull ${var.aws_account_id}.dkr.ecr.${var.aws_region}.amazonaws.com/task-backend:latest
     docker pull ${var.aws_account_id}.dkr.ecr.${var.aws_region}.amazonaws.com/task-frontend:latest
 
-    # Run backend
+    # Run backend — DB credentials passed as environment variables
+    # Values come from Terraform variables which are sourced from GitHub Secrets
     docker run -d \
       --name task-backend \
       --restart unless-stopped \
       -p 3000:3000 \
+      -e DB_HOST=${var.db_host} \
+      -e DB_PORT=5432 \
+      -e DB_NAME=${var.db_name} \
+      -e DB_USER=${var.db_username} \
+      -e DB_PASSWORD=${var.db_password} \
       ${var.aws_account_id}.dkr.ecr.${var.aws_region}.amazonaws.com/task-backend:latest
 
     # Wait for backend to be ready

infra/terraform/rds.tf

@@ -0,0 +1,132 @@
+# ─────────────────────────────────────────────
+# RDS — PostgreSQL for Scalable Task Platform
+# Week 7 | infra/terraform/rds.tf
+# ─────────────────────────────────────────────
+
+# ── DB Subnet Group ──────────────────────────
+# RDS needs to know which subnets it can live in.
+# We use the private subnets so it is never
+# reachable from the public internet.
+resource "aws_db_subnet_group" "tasks" {
+  name       = "${var.project_name}-db-subnet-group"
+  subnet_ids = aws_subnet.private[*].id
+
+  tags = {
+    Name    = "${var.project_name}-db-subnet-group"
+    Project = var.project_name
+  }
+}
+
+# ── Security Group: RDS ──────────────────────
+# Only the EC2 instance security group may reach
+# the database on port 5432. No public access.
+resource "aws_security_group" "rds" {
+  name        = "${var.project_name}-rds-sg"
+  description = "Allow PostgreSQL access from EC2 only"
+  vpc_id      = aws_vpc.main.id
+
+  ingress {
+    description     = "PostgreSQL from EC2"
+    from_port       = 5432
+    to_port         = 5432
+    protocol        = "tcp"
+    security_groups = [aws_security_group.ec2.id]
+  }
+
+  egress {
+    description = "Allow all outbound"
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+
+  tags = {
+    Name    = "${var.project_name}-rds-sg"
+    Project = var.project_name
+  }
+}
+
+# ── RDS Parameter Group ──────────────────────
+# Explicit parameter group gives you a place to
+# tune Postgres settings later without replacing
+# the instance.
+resource "aws_db_parameter_group" "tasks" {
+  name   = "${var.project_name}-pg16"
+  family = "postgres16"
+
+  tags = {
+    Name    = "${var.project_name}-pg16"
+    Project = var.project_name
+  }
+}
+
+# ── RDS Instance ─────────────────────────────
+resource "aws_db_instance" "tasks" {
+  identifier = "${var.project_name}-db"
+
+  # Engine
+  engine         = "postgres"
+  engine_version = "16"
+  instance_class = "db.t3.micro" # Free-tier eligible
+
+  # Storage
+  allocated_storage     = 20
+  max_allocated_storage = 100 # Enable storage autoscaling up to 100 GB
+  storage_type          = "gp2"
+  storage_encrypted     = true
+
+  # Credentials — sourced from Terraform variables
+  # which are populated from GitHub Secrets via the pipeline
+  db_name  = var.db_name
+  username = var.db_username
+  password = var.db_password
+
+  # Network
+  db_subnet_group_name   = aws_db_subnet_group.tasks.name
+  vpc_security_group_ids = [aws_security_group.rds.id]
+  publicly_accessible    = false
+  multi_az               = false # Single-AZ is fine for this stage
+
+  # Maintenance
+  parameter_group_name    = aws_db_parameter_group.tasks.name
+  backup_retention_period = 7
+  backup_window           = "03:00-04:00"
+  maintenance_window      = "Mon:04:00-Mon:05:00"
+  deletion_protection     = false # Set to true before production hardening (Week 10)
+
+  # Lifecycle — prevent accidental destroy on credential rotation
+  lifecycle {
+    ignore_changes = [password]
+  }
+
+  skip_final_snapshot = true # Change to false and set final_snapshot_identifier for production
+
+  tags = {
+    Name    = "${var.project_name}-db"
+    Project = var.project_name
+  }
+}
+
+# ── Outputs ───────────────────────────────────
+# The EC2 user-data script and any future modules
+# that need the DB endpoint will read these.
+output "rds_endpoint" {
+  description = "RDS instance endpoint (host:port)"
+  value       = aws_db_instance.tasks.endpoint
+}
+
+output "rds_hostname" {
+  description = "RDS hostname only (no port)"
+  value       = aws_db_instance.tasks.address
+}
+
+output "rds_port" {
+  description = "RDS port"
+  value       = aws_db_instance.tasks.port
+}
+
+output "rds_db_name" {
+  description = "Database name"
+  value       = aws_db_instance.tasks.db_name
+}

infra/terraform/variables.tf

@@ -36,4 +36,26 @@ variable "private_subnet_cidr" {
   description = "CIDR block for the private subnet"
   type        = string
   default     = "10.0.2.0/24"
-}
+}
+variable "db_name" {
+  description = "PostgreSQL database name"
+  type        = string
+  default     = "tasksdb"
+}
+
+variable "db_username" {
+  description = "PostgreSQL master username"
+  type        = string
+  sensitive   = true
+}
+
+variable "db_password" {
+  description = "PostgreSQL master password"
+  type        = string
+  sensitive   = true
+}
+variable "db_host" {
+  description = "RDS instance hostname — output from aws_db_instance.tasks.address"
+  type        = string
+  sensitive   = true
+}