For Red Hat.

host-report.rb

#!/usr/bin/ruby

require 'time'
require 'rest-client'
require 'json'
require 'yaml'
require 'mail'

ME = 'satellite.ivytech.edu'
url = "https://#{ME}"
foreman_url = "#{url}/api/v2"

$email_to = 'its-infra@lists.ivytech.edu'
$username = 'admin'
$password = 'password'
$expire = '864000'.to_i
PER_PAGE = 100

org_name = 'Ivy Tech Community College'

mailer_settings = YAML.load(File.read('/etc/foreman/email.yaml'))['production']
Mail.defaults do 
  delivery_method mailer_settings['delivery_method'], mailer_settings['smtp_settings'].inject({}){|memo,(k,v)| memo[k.to_sym] = v; memo}
end

# Performs a GET using the passed URL location
def get_json(location, page = 1)
  location = "#{location}?page=#{page}&per_page=#{PER_PAGE}"
  response = RestClient::Request.new(
    :method => :get,
    :url => location,
    :user => $username,
    :password => $password,
    :headers => { :accept => :json,
    :content_type => :json }
  ).execute
  JSON.parse(response.to_str)
end

# Has the host checked in within ten days?
def too_late?(host)
  last = host.fetch('subscription_facet_attributes', {}).fetch('last_checkin', nil)
  if last.nil?
    true
  else
    Time.now.to_i - Time.parse(last).to_i > $expire
  end
end
 
def lineitem(host, style)
  red = "border: none; background-color: rgba(255, 99, 71, 0.5); padding: 8px; font-family: Arial, Helvetica, sans-serif"
  if too_late?(host)
    style = red
  end
  <<-"EOF"
    <tr>
      <td style="#{style}">#{host['name']}</td>
      <td style="#{style}">#{host.fetch('subscription_facet_attributes', {}).fetch('last_checkin', 'N/A')}</td>
      <td style="#{style}">#{host.fetch('content_facet_attributes', {}).fetch('errata_counts', {}).fetch('security', "N/A").to_s}</td>
      <td style="#{style}">#{host.fetch('content_facet_attributes', {}).fetch('errata_counts', {}).fetch('bugfix', "N/A").to_s}</td>
      <td style="#{style}">#{host.fetch('content_facet_attributes', {}).fetch('upgradable_package_count', "N/A").to_s}</td>
    </tr>
EOF
end

def table_def
  th_style = "border: none; background-color: DodgerBlue; color: white; font-size: 18px; font-family: Arial, Helvetica, sans-serif; texgt-align: center"
  <<-"EOF"
  <h1 style="font-family: Arial, Helvetica, sans-serif">Satellite Host Report</h1>
  <table style="border-collapse: collapse; width: 100%">
    <tr>
      <th style="#{th_style}">Host</th>
      <th style="#{th_style}">Last Checkin</th>
      <th style="#{th_style}">Security</th>
      <th style="#{th_style}">Bugfixes</th>
      <th style="#{th_style}">Upgradeable</th>
    </tr>
EOF
end

def table_end 
  "  </table>"
end

###### Do the things ######

grey = "border: none; background-color: #f2f2f2; padding: 8px; font-family: Arial, Helvetica, sans-serif"
nocolor = "border: none; padding: 8px; font-family: Arial, Helvetica, sans-serif"
color_counter=0

body = table_def

hostcount = get_json("#{foreman_url}/hosts")['total'].to_f
pages = (hostcount / PER_PAGE).ceil

1.upto(pages) do |page|
  hosts = get_json("#{foreman_url}/hosts", page)['results']
  hosts.each do |host|
    next if host['name'].eql? ME
    color_counter % 2 == 0 ? body.concat(lineitem(host, nocolor)) : body.concat(lineitem(host, grey))
    color_counter += 1
  end
end

body.concat(table_end)

mail = Mail.new do
  from mailer_settings['smtp_settings']['user_name']
  to $email_to
  subject "Satellite Host Report"

  text_part do
    body 'This message is in html format.'
  end

  html_part do
    content_type 'text/html; charset=UTF-8'
    body body
  end
end

mail.deliver!