Deploying a RDS Instance into a Specific VPC

External

• Tutorial: Create an Amazon VPC for Use with an Amazon RDS DB Instance

Internal

• Amazon Relation Database Concepts
• Amazon Relational Database Operations

Procedure

The deployment of a RDS instance in a specific VPC consists in the following steps:

1. Create at least two dedicated subnets, in two different availability zones. One subnet is not sufficient, the DB deployment will fail.

This is optional, and it's probably best to do for the clarity of the solution, but it's probably not necessary.

The subnet does not need a route to the internet.

Resources:
  ...  
  PostgresSubnet1:
    Type: AWS::EC2::Subnet
    Properties:
      VpcId:
        Fn::ImportValue: !Sub ${MicroworldName}-vpc-id
      CidrBlock: !Ref PostgreSQLSubnet1CIDRBlock
      #
      # We explicitly associate the subnet with an availability zone, because we've seen situations in the
      # past when AWS, left to its own devices, would deploy both subnets in the same availability zone, and
      # that would prevent the ALB from starting. We use the same availability zone as Subnet1
      #
      AvailabilityZone: !Sub ${AWS::Region}${Subnet1AvailabilityZoneSuffix}
      MapPublicIpOnLaunch: false
      Tags:
        - Key: Name
          Value: !Sub ${MicroworldName}-${EnvironmentName}-postgres-subnet1

  PostgresSubnet1RouteTable:
    Type: AWS::EC2::RouteTable
    Properties:
      VpcId:
        Fn::ImportValue: !Sub ${MicroworldName}-vpc-id
      Tags:
        - Key: Name
          Value: !Sub ${MicroworldName}-${EnvironmentName}-postgres-subnet1-rt

  PostgresSubnet1RouteTableAssociation:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      RouteTableId: !Ref PostgresSubnet1RouteTable
      SubnetId: !Ref PostgresSubnet1

  #
  # We don't need a route to NAT, as the PostgreSQL instance does not need internet access
  #

  PostgresSubnet2:
    Type: AWS::EC2::Subnet
    Properties:
      VpcId:
        Fn::ImportValue: !Sub ${MicroworldName}-vpc-id
      CidrBlock: !Ref PostgreSQLSubnet2CIDRBlock
      #
      # We explicitly associate the subnet with an availability zone, because we've seen situations in the
      # past when AWS, left to its own devices, would deploy both subnets in the same availability zone, and
      # that would prevent the ALB from starting. We use the same availability zone as Subnet2
      #
      AvailabilityZone: !Sub ${AWS::Region}${Subnet2AvailabilityZoneSuffix}
      MapPublicIpOnLaunch: false
      Tags:
        - Key: Name
          Value: !Sub ${MicroworldName}-${EnvironmentName}-postgres-subnet2

  PostgresSubnet2RouteTable:
    Type: AWS::EC2::RouteTable
    Properties:
      VpcId:
        Fn::ImportValue: !Sub ${MicroworldName}-vpc-id
      Tags:
        - Key: Name
          Value: !Sub ${MicroworldName}-${EnvironmentName}-postgres-subnet2-rt

  PostgresSubnet2RouteTableAssociation:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      RouteTableId: !Ref PostgresSubnet2RouteTable
      SubnetId: !Ref PostgresSubnet2

  #
  # We don't need a route to NAT, as the PostgreSQL instance does not need internet access
  #

2. Create a DB subnet Group.

See:

AWS::RDS::DBSubnetGroup

3. Create a VPC security group for the RDS instance.

  PostgresSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupName: !Sub ${MicroworldName}-${EnvironmentName}-postgres-sg
      VpcId:
        Fn::ImportValue: !Sub ${MicroworldName}-vpc-id
      GroupDescription: !Sub Security group for ${MicroworldName} ${EnvironmentName} PostgreSQL instance
      SecurityGroupIngress:
        - IpProtocol: -1
          CidrIp: 0.0.0.0/0

4. Configure the RDS instance with all of the above.

See:

AWS::RDS::DBInstance