AWS RDS Configuration Guide — Instances, Parameters, Backups, and Snapshots

# Create a PostgreSQL instance
aws rds create-db-instance \
  --db-instance-identifier my-postgres \
  --db-instance-class db.t3.medium \
  --engine postgres \
  --engine-version 16.2 \
  --master-username admin \
  --master-user-password "SecurePass123!" \
  --allocated-storage 100 \
  --storage-type gp3 \
  --storage-encrypted \
  --vpc-security-group-ids sg-xxxxxxxx \
  --db-subnet-group-name my-subnet-group \
  --backup-retention-period 7 \
  --no-publicly-accessible \
  --multi-az \
  --deletion-protection

# Check creation status
aws rds describe-db-instances \
  --db-instance-identifier my-postgres \
  --query 'DBInstances[0].DBInstanceStatus'

# RDS security group — allow port 5432 only from the app server SG
aws ec2 authorize-security-group-ingress \
  --group-id sg-rds-xxxxxx \
  --protocol tcp \
  --port 5432 \
  --source-group sg-app-xxxxxx

# Verify public accessibility
aws rds describe-db-instances \
  --query 'DBInstances[0].PubliclyAccessible'

# Create a parameter group
aws rds create-db-parameter-group \
  --db-parameter-group-name my-postgres16 \
  --db-parameter-group-family postgres16 \
  --description "Custom PostgreSQL 16 params"

# Modify parameters
aws rds modify-db-parameter-group \
  --db-parameter-group-name my-postgres16 \
  --parameters \
    "ParameterName=shared_buffers,ParameterValue={DBInstanceClassMemory/4},ApplyMethod=pending-reboot" \
    "ParameterName=log_min_duration_statement,ParameterValue=1000,ApplyMethod=immediate" \
    "ParameterName=max_connections,ParameterValue=200,ApplyMethod=pending-reboot"

# Apply the parameter group to the instance
aws rds modify-db-instance \
  --db-instance-identifier my-postgres \
  --db-parameter-group-name my-postgres16 \
  --apply-immediately

# Check automated backup settings
aws rds describe-db-instances \
  --db-instance-identifier my-postgres \
  --query 'DBInstances[0].{Backup:BackupRetentionPeriod,Window:PreferredBackupWindow}'

# Create a manual snapshot
aws rds create-db-snapshot \
  --db-instance-identifier my-postgres \
  --db-snapshot-identifier my-postgres-snap-$(date +%Y%m%d)

# List snapshots
aws rds describe-db-snapshots \
  --db-instance-identifier my-postgres \
  --query 'DBSnapshots[*].[DBSnapshotIdentifier,SnapshotCreateTime,Status]' \
  --output table

# Restore from a snapshot
aws rds restore-db-instance-from-db-snapshot \
  --db-instance-identifier my-postgres-restored \
  --db-snapshot-identifier my-postgres-snap-20250527

# Create a read replica
aws rds create-db-instance-read-replica \
  --db-instance-identifier my-postgres-reader \
  --source-db-instance-identifier my-postgres \
  --db-instance-class db.t3.small

# Check the replica endpoint
aws rds describe-db-instances \
  --db-instance-identifier my-postgres-reader \
  --query 'DBInstances[0].Endpoint'

# Look up the endpoint
aws rds describe-db-instances \
  --db-instance-identifier my-postgres \
  --query 'DBInstances[0].Endpoint.Address' \
  --output text

# Connection test from EC2
psql -h my-postgres.xxxxxxxx.ap-northeast-2.rds.amazonaws.com \
  -U admin -d postgres -p 5432