Cleanup use of extra_dib_elements

Removed extra_dib_elements option from the disk image building role
and created a default variable entry in the installation and test
playbooks to allow a user to manually trigger the behavior.

Change-Id: I707f1fd25cf9a6cec4f70a6d65d89d4363d69153

playbooks/install.yaml

@@ -7,7 +7,7 @@
   roles:
     - { role: bifrost-prep-for-install, when: skip_install is not defined }
     - ironic-install
-    - { role: bifrost-create-dib-image, dib_imagename: "{{ deploy_image }}", dib_imagetype: "qcow2", dib_os_element: "debian", dib_elements: "vm serial-console simple-init", when: create_image_via_dib == true and transform_boot_image == false }
+    - { role: bifrost-create-dib-image, dib_imagename: "{{ deploy_image }}", dib_imagetype: "qcow2", dib_os_element: "debian", dib_elements: "vm serial-console simple-init {{ extra_dib_elements|default('') }}", when: create_image_via_dib == true and transform_boot_image == false }
     - { role: bifrost-create-bootable-image, when: create_image_via_dib == false and transform_boot_image == true }
   environment:
     http_proxy: "{{ lookup('env','http_proxy') }}"

playbooks/roles/bifrost-create-dib-image/README.md

@@ -21,15 +21,12 @@ build_ramdisk: false
 
 The dib_env_vars are settings for the diskimage-builder environment variables
 which allow settings to be passed to elements that are being utilized to build
-a disk image.  More information on diskimage-builder can be found at
+a disk image.  More information on diskimage-builder can be found at:
-http://git.openstack.org/cgit/openstack/diskimage-builder/.  Additionally, an
+http://git.openstack.org/cgit/openstack/diskimage-builder/
-extra_dib_elements setting exists which is a space separated list of elements
-to incorporate into the image.
 
 dib_env_vars:
   DIB_CLOUD_INIT_DATASOURCES: "ConfigDrive"
   ELEMENTS_PATH: "/opt/stack/diskimage-builder/elements"
-extra_dib_elements: ""
 
 http_boot_folder, deploy_image_filename, and deploy_image all control the final
 destination of the built image.

playbooks/roles/bifrost-create-dib-image/defaults/main.yml

@@ -4,8 +4,6 @@ dib_env_vars:
   ELEMENTS_PATH: "/opt/stack/diskimage-builder/elements"
   http_proxy: "{{ lookup('env','http_proxy') }}"
   https_proxy: "{{ lookup('env','https_proxy') }}"
-# extra_dib_elements is a space separated list of elements.
-extra_dib_elements: ""
 build_ramdisk: false
 dib_trace: false
 dib_uncompressed: false

playbooks/test-bifrost-dynamic.yaml

@@ -50,7 +50,7 @@
     - role: ironic-install
       cleaning: false
       testing: true
-    - { role: bifrost-create-dib-image, dib_imagetype: "qcow2", dib_imagename: "{{deploy_image}}", dib_os_element: "debian", dib_elements: "vm serial-console simple-init {{extra_dib_elements}}", when: create_image_via_dib == true and transform_boot_image == false }
+    - { role: bifrost-create-dib-image, dib_imagetype: "qcow2", dib_imagename: "{{deploy_image}}", dib_os_element: "debian", dib_elements: "vm serial-console simple-init {{ extra_dib_elements|default('') }}", when: create_image_via_dib == true and transform_boot_image == false }
     - { role: bifrost-create-bootable-image, when: create_image_via_dib == false and transform_boot_image == true }
   environment:
     http_proxy: "{{ lookup('env','http_proxy') }}"