Allow Orchestration of Image Backend

Adds a horizon::image_backend parameter that can be overriden to allow
explicit definition of the supported image types etc. that are supported for
the end user.  The underlying python representation per setting is an array of
tuples, however in puppet and hiera this is a hash as all options have an
order of 2.  A typical configuration may look like:

  horizon::image_backend:
    image_formats:
      '':    'Select image format'
      qcow2: 'QCOW2 - QEMU Emulator'
      raw:   'Raw'

Change-Id: Ieb92240ed86f67b73911ec627312093e797fa15f

manifests/init.pp

@@ -243,6 +243,12 @@
 #    All entities will be created in the default domain.
 #    Default to undefined
 #
+#  [*image_backend*]
+#    (optional) Overrides the default image backend settings.  This allows the list of supported
+#    image types etc. to be explicitly defined.
+#    Example: image_backend => { 'image_formats' => { '' => 'Select type', 'qcow2' => 'QCOW2' } }
+#    Default to empty hash
+#
 # === Examples
 #
 #  class { 'horizon':
@@ -301,6 +307,7 @@ class horizon(
   $api_versions                        = {},
   $keystone_multidomain_support        = false,
   $keystone_default_domain             = undef,
+  $image_backend                       = {},
   # DEPRECATED PARAMETERS
   $can_set_mount_point                 = undef,
   $vhost_extra_params                  = undef,

spec/classes/horizon_init_spec.rb

@@ -332,6 +332,56 @@ describe 'horizon' do
 
       it { is_expected.not_to contain_file(params[:file_upload_temp_dir]) }
     end
+
+    context 'with image_backend' do
+      before do
+        params.merge!({
+          :image_backend => {
+            'image_formats' => {
+              ''      => 'Select image format',
+              'aki'   => 'AKI - Amazon Kernel Image',
+              'ami'   => 'AMI - Amazon Machine Image',
+              'ari'   => 'ARI - Amazon Ramdisk Image',
+              'iso'   => 'ISO - Optical Disk Image',
+              'qcow2' => 'QCOW2 - QEMU Emulator',
+              'raw'   => 'Raw',
+              'vdi'   => 'VDI',
+              'vhi'   => 'VHI',
+              'vmdk'  => 'VMDK',
+            },
+            'architectures' => {
+              ''        => 'Select architecture',
+              'x86_64'  => 'x86-64',
+              'aarch64' => 'ARMv8',
+            },
+          },
+        })
+      end
+
+      it 'configures OPENSTACK_IMAGE_BACKEND' do
+        verify_concat_fragment_contents(catalogue, 'local_settings.py', [
+          "OPENSTACK_IMAGE_BACKEND = {",
+          "    'image_formats': [",
+          "        ('', _('Select image format')),",
+          "        ('aki', _('AKI - Amazon Kernel Image')),",
+          "        ('ami', _('AMI - Amazon Machine Image')),",
+          "        ('ari', _('ARI - Amazon Ramdisk Image')),",
+          "        ('iso', _('ISO - Optical Disk Image')),",
+          "        ('qcow2', _('QCOW2 - QEMU Emulator')),",
+          "        ('raw', _('Raw')),",
+          "        ('vdi', _('VDI')),",
+          "        ('vhi', _('VHI')),",
+          "        ('vmdk', _('VMDK')),",
+          "    ], # image_formats",
+          "    'architectures': [",
+          "        ('', _('Select architecture')),",
+          "        ('x86_64', _('x86-64')),",
+          "        ('aarch64', _('ARMv8')),",
+          "    ], # architectures",
+          "} # OPENSTACK_IMAGE_BACKEND",
+        ])
+      end
+    end
   end
 
   context 'on RedHat platforms' do

templates/local_settings.py.erb

@@ -256,6 +256,17 @@ OPENSTACK_NEUTRON_NETWORK = {
 #         ('vmdk', _('VMDK'))
 #     ]
 # }
+<%- if !(@image_backend.empty?) -%>
+OPENSTACK_IMAGE_BACKEND = {
+  <%- @image_backend.each do |opt_name,opt_val| -%>
+    '<%= opt_name %>': [
+      <%- opt_val.each do |val,label| -%>
+        ('<%= val %>', _('<%= label %>')),
+      <%- end -%>
+    ], # <%= opt_name %>
+  <%- end -%>
+} # OPENSTACK_IMAGE_BACKEND
+<%- end -%>
 
 # OPENSTACK_ENDPOINT_TYPE specifies the endpoint type to use for the endpoints
 # in the Keystone service catalog. Use this setting when Horizon is running