vpc 4.3 Multiple Network Interface Design

Description

This document covers changes to the VPC service for support of multiple network interfaces.

Analysis

This section describes investigation / analysis of multiple network interface behaviour.

Attach/Detach for Pending Instance

AWS/EC2 forbids network interface attachment modifications for a pending instance.

Resource Lifecycle

Network interface resources must be associated with the interface and not with an instance. Resources used by an eni may be released when an instance is terminated if the attachment specifies delete-on-terminate behaviour.

Model / Persistence

Entities

The NetworkInterface entity is updated to support querying for an attachment and to set the interface state based on attachment state (for hot/cold attach cases)

The PrivateAddress entity now references either an instance or a network interface for tracking resource ownership.

VmType is updated for persistence of the network interfaces limit for the type.

Service

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

Managers

The VpcManager is updated with support for attach and detach of network interfaces.

VmTypesManager is updated to allow the network interfaces limit to be configured.

Backend

Instance State Polling

The polling of cluster controllers for instance state is updated to include processing of network interface attachments. This is used for attaching and detaching transitions.

Network Broadcast

The network broadcast is updated to include the attachment identifier for network interfaces:

 <instances>
    <instance name="i-1b5c4503">
      <ownerId>000994694045</ownerId>
      <macAddress>d0:0d:a2:f1:51:a8</macAddress>
      <privateIp>172.31.2.226</privateIp>
      <vpc>vpc-3b1fdc87</vpc>
      <subnet>subnet-893ca466</subnet>
      <networkInterfaces>
        <networkInterface name="eni-a2f151a8">
          <ownerId>000994694045</ownerId>
          <deviceIndex>0</deviceIndex>
          <attachmentId>eni-attach-e98cf499</attachmentId>
          <macAddress>d0:0d:a2:f1:51:a8</macAddress>
          <privateIp>172.31.2.226</privateIp>
          <sourceDestCheck>true</sourceDestCheck>
          <vpc>vpc-3b1fdc87</vpc>
          <subnet>subnet-893ca466</subnet>
          <securityGroups>
            <value>sg-6300851f</value>
          </securityGroups>
        </networkInterface>
      </networkInterfaces>
      <securityGroups>
        <value>sg-6300851f</value>
      </securityGroups>
    </instance>

Network Interface Route States

The network broadcast processing also fires events ( VpcRouteStateInvalidationEvent ) for any invalid route states that are detected. VpcWorkflow has a task to process any routes that may have incorrect states and update them.