vpc 4.3 NAT Gateway Design

Description
Model / Persistence
- Entities
- Persistence Facades / DAOs
Service
- Managers
Backend
- VPC Workflow
- Network Broadcast
References

Description

This document covers changes to the VPC service for support of NAT gateways.

Model / Persistence

Entities

A new NatGateway class is introduced for persistence of NAT gateway metadata. The entity has references to resources it uses:

VPC
Subnet
Network interface

and also the identifiers for each resource. When the NAT gateway is deleted or failed the reference to other entities are cleared but the resource identifier fields are not.

Persistence Facades / DAOs

A new NatGateways / PersistenceNatGateways facade is added for working with NAT gateways.

Service

This section covers functionality related to the user facing VPC service implementation.

Managers

The VpcManager is updated with support for management of NAT gateways.

The ComputeService is updated with support for describing NAT gateways.

Backend

VPC Workflow

NAT gateways have state transitions that occur outside of API actions or polling of cluster resources. A new VpcWorkflow class is introduced to handle this work. Work performed here is a candidate for replacement by alternative workflow implementations such as Simple Workflow.

On creation of a NAT gateway the resource is in a "pending" state. The workflow is responsible for transitioning to "available" by:

Creating the related network interface resource
Associating the elastic IP

On deletion of a NAT gateway the resource is in a "deleting" state. The workflow is responsible for transitioning to "deleted" by:

Disassociating the elastic IP
Deleting the network interface

NAT gateway resources in a "failed" or "deleted" state remain visible via the API for an hour. The workflow is responsible for cleanup of expired NAT gateway metadata.

Network Broadcast

The network broadcast is updated to include information for NAT gateways:

<vpc name="vpc-7377904f">
  <ownerId>000476990416</ownerId>
  <cidr>10.10.0.0/16</cidr>
  <dhcpOptionSet>dopt-f6703e05</dhcpOptionSet>
  <subnets>
    ...
  </subnets>
  <networkAcls>
    ...
  </networkAcls>
  <routeTables>
    <routeTable name="rtb-0d6760e5">
      <ownerId>000476990416</ownerId>
      <routes>
        <route>
          <destinationCidr>10.10.0.0/16</destinationCidr>
          <gatewayId>local</gatewayId>
        </route>
        <route>
          <destinationCidr>1.1.1.1/32</destinationCidr>
          <natGatewayId>nat-99528bb072b83cf9f</natGatewayId>
        </route>
      </routes>
    </routeTable>
    <routeTable name="rtb-380d260d">
      <ownerId>000476990416</ownerId>
      <routes>
        <route>
          <destinationCidr>10.10.0.0/16</destinationCidr>
          <gatewayId>local</gatewayId>
        </route>
      </routes>
    </routeTable>
  </routeTables>
  <natGateways>
    <natGateway name="nat-99528bb072b83cf9f">
      <ownerId>000476990416</ownerId>
      <macAddress>d0:0d:0f:bb:04:f4</macAddress>
      <publicIp>10.116.132.146</publicIp>
      <privateIp>10.10.10.8</privateIp>
      <vpc>vpc-7377904f</vpc>
      <subnet>subnet-3e787e00</subnet>
    </natGateway>
  </natGateways>
  <internetGateways>
    <value>igw-993ae7e7</value>
  </internetGateways>
</vpc>