OpWorks Stacks managed instance self-update to have IPv6 address.

AllowDescribeNetworkInterfacesAndAssignIpv6Address

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "VisualEditor0",
            "Effect": "Allow",
            "Action": [
                "ec2:DescribeNetworkInterfaces",
                "ec2:AssignIpv6Addresses"
            ],
            "Resource": "*"
        }
    ]
}

libraries::ec2_interface_v6_setup.rb

# Copyright 2019, Joshua Goodall. MIT license.

require 'aws-sdk-ec2'

class EC2InterfaceV6Setup
  attr_reader :instance_id, :client, :logger

  def initialize(instance_id, aws_region, logger = Chef::Log)
    @instance_id = instance_id
    @client = Aws::EC2::Client.new(region: aws_region)
    @logger = logger
  end

  def run
    interfaces.each do |interface|
      if interface.ipv_6_addresses.empty?
        logger.info "adding new IPv6 address to interface #{interface.network_interface_id}"
        response = assign_ipv6_address(interface)
        logger.info "result of adding IPv6 address: interface #{response.network_interface_id} now has IPv6 address(es): #{response.assigned_ipv_6_addresses.join(', ')}"
      else
        logger.info "interface #{interface.network_interface_id} already has IPv6 address(es): #{interface.ipv_6_addresses.map(&:ipv_6_address).join(', ')}"
      end
    end
  end

  def assign_ipv6_address(interface)
    client.assign_ipv_6_addresses({
      ipv_6_address_count: 1,
      network_interface_id: interface.network_interface_id
    })
  end

  def interfaces
    client.describe_network_interfaces(filters: filters).network_interfaces
  end

  def filters
    [
      {name: 'attachment.instance-id', values: [instance_id]},
      {name: 'attachment.device-index', values: ["0"]}
    ]
  end
end

recipes::configure.rb

# Cookbook Name:: inopinatus
# Recipe:: configure
#
# Copyright 2019, Joshua Goodall. MIT license.

include_recipe 'inopinatus::ipv6'

# ...other lines...

recipes::ipv6.rb

# Cookbook Name:: inopinatus
# Recipe:: ipv6
#
# Copyright 2019, Joshua Goodall. MIT license.

ec2_instance_id = search("aws_opsworks_instance", "self:true").first['ec2_instance_id']
region = search("aws_opsworks_stack").first['region']

v6setup = EC2InterfaceV6Setup.new(ec2_instance_id, region)
v6setup.run

This gist allows instances launched by OpsWorks Stacks to update themselves such that they're assigned an IPv6 address, which currently doesn't happen even if the VPC is configured as such. The address itself will flow through within seconds/minutes via DHCP refresh.

Beforehand:

• Ensure that IPv6 is fully and correctly configured for the VPC subnets, route tables, security groups and ACLs in question.
• Verify that the IAM policy is right for you.

Steps:

• Attach IAM policy to the OpsWorks ec2 instance role e.g. as an inline policy.
• Place Ruby files in a custom cookbook (subsitute '/' for '::' in filenames).
• Ensure the packaged custom cookbook depends on/bundles the aws cookbook from Chef Supermarket.
• Ensure custom inopinatus::configure recipe is included the Configure step of relevant OpsWorks layer.

Tested with Ubuntu 18.04LTS, but should work on any current OpsWorks-launched Linux type.