Add new enable_container_images_build setting

The new `enable_container_images_build` setting allows to control
whether to install the required packages to build container images on
the undercloud. It defaults to 'true' to be backward compatible.

Change-Id: Ia3379cf66b1d6b180def69c2a5b22b2602baacef

elements/puppet-stack-config/puppet-stack-config.yaml.template

@@ -777,6 +777,7 @@ enable_telemetry: {{ENABLE_TELEMETRY}}
 enable_legacy_ceilometer_api: {{ENABLE_LEGACY_CEILOMETER_API}}
 enable_ui: {{ENABLE_UI}}
 enable_cinder: {{ENABLE_CINDER}}
+enable_container_images_build: {{ENABLE_CONTAINER_IMAGES_BUILD}}
 
 # Path to install configuration files
 tripleo_install_user: {{TRIPLEO_INSTALL_USER}}

instack_undercloud/undercloud.py

@@ -326,6 +326,11 @@ _opts = [
                 help=('Whether to install novajoin metadata service in '
                       'the Undercloud.')
                 ),
+    cfg.BoolOpt('enable_container_images_build',
+                default=True,
+                help=('Whether to enable docker container images to be build '
+                      'on the undercloud.')
+                ),
     cfg.StrOpt('ipa_otp',
                default='',
                help=('One Time Password to register Undercloud node with '

undercloud.conf.sample

@@ -199,6 +199,10 @@
 # List of enabled bare metal drivers. (list value)
 #enabled_drivers = pxe_ipmitool,pxe_drac,pxe_ilo
 
+# Whether to enable docker container images to be build on the undercloud.
+# Note this installs the required packages but does not build the images
+# automatically.
+#enable_container_images_build = true
 
 # An optional docker 'registry-mirror' that will be
 # configured in /etc/docker/daemon.json.