introduce install_dib varible

- This change introduces a new install_dib varible.
- This change decouples installation of disk image
  builder and dib-utils form building a dib image.
- To maintain backwards compatiblity install_dib
  default to the value of create_image_via_dib

Change-Id: I06fb4a2df73702f06393c552f6ba9f705a4eb994

playbooks/roles/bifrost-ironic-install/defaults/main.yml

@@ -10,6 +10,8 @@ ironicclient_source_install: false
 shade_source_install: true
 # Setting to utilize diskimage-builder to create a bootable image.
 create_image_via_dib: true
+# Setting to install diskimage-builder
+install_dib: "{{ create_image_via_dib }}"
 # Setting to prepend a partition image with a boot sector and partition table.
 transform_boot_image: false
 # If testing is true, then the environment is setup for using libvirt

playbooks/roles/bifrost-ironic-install/tasks/main.yml

@@ -90,13 +90,13 @@
   include: pip_install.yml
     package=dib-utils
     state=present
-  when: skip_install is not defined and create_image_via_dib == true
+  when: skip_install is not defined and install_dib == true
 - name: "Diskimage-builder - Install"
   include: pip_install.yml
     package=diskimage-builder
     sourcedir={{ dib_git_folder }}
     source_install=true
-  when: skip_install is not defined and create_image_via_dib == true
+  when: skip_install is not defined and install_dib == true
 - name: "Ironic Client - Install"
   include: pip_install.yml
     package=python-ironicclient

releasenotes/notes/introduce-install-dib-1e53da734a878dac.yaml

@@ -0,0 +1,6 @@
+---
+other:
+  - A new install_dib varible has been introduced to the ironic install role
+    to control installation of disk image builder and dib-utils. 
+    To maintain  the previous behavior install_dib will default to
+    the value of create_image_via_dib.