How to upgrade HAProxy on OpsWorks - haproxy

Question

We are using an AWS OpsWorks stack with Chef Version 11.10. with the default HAProxy Layer. We would like to upgrade the HAProxy to the latest version 1.6-stable (from the default 1.4-stable).
There seems to be a dedicated PPA for our Ubuntu version.
But where can we make OpsWorks use this PPA to install HAProxy?
In the default cookbook there is a default attributes file that has the following lines:
default[:haproxy][:version] = '1.4.22'
default[:haproxy][:patchlevel] = '1'
default[:haproxy][:rpm] = "haproxy-#{node[:haproxy][:version]}-#{node[:haproxy][:patchlevel]}.#{rhel_arch}.rpm"
default[:haproxy][:rpm_url] = "#{node[:opsworks_commons][:assets_url]}/packages/#{node[:platform]}/#{node[:platform_version]}/#{node[:haproxy][:rpm]}"
Overwriting the file in our cookbooks and naïvely changing the version number here does not have the desired effect.

Answer 1

We ended up overwriting the recipe haproxy/recipes/default.rb like so:
#Install software-properties-common if not installed
package 'software-properties-common' do
action :install
end
#Add PPA for haproxy 1.6 and update repo
execute "add-ppa-update" do
command "add-apt-repository ppa:vbernat/haproxy-1.6 && apt-get update -y"
action :run
end
package "haproxy" do
retries 3
retry_delay 5
version '1.6.4-3ppa1~trusty'
action :install
end
if platform?('debian','ubuntu')
template '/etc/default/haproxy' do
source 'haproxy-default.erb'
owner 'root'
group 'root'
mode 0644
end
end
include_recipe 'haproxy::service'
template '/etc/haproxy/haproxy.cfg' do
source 'haproxy.cfg.erb'
owner 'root'
group 'root'
mode 0644
notifies :restart, "service[haproxy]"
end
template "/etc/haproxy/server.pem" do
source "server.pem.erb"
owner 'root'
group 'root'
mode 0600
notifies :restart, "service[haproxy]"
end
service 'haproxy' do
action [:enable, :start]
end
Additionally we needed to update the haproxy.conf to work with the new version.
Everything runs beautifully now.