Switch to Debian Stretch for building DIB images

It seems that Jessie is no longer supported, and its backports repo
is no longer available, hence all DIB jobs fail.

Depends-On: https://review.openstack.org/#/c/653453/
Change-Id: I7973c8da057a678e6285ecc9418a4862bc1d3feb

doc/source/user/howto.rst

@@ -343,7 +343,7 @@ Bifrost supports the ability for a user to build a custom IPA ramdisk
 utilizing the diskimage-builder element "ironic-agent".  In order to utilize
 this feature, the ``download_ipa`` setting must be set to ``false`` and the
 create_ipa_image must be set to "true".  By default, the install playbook will
-build a Debian jessie based IPA image, if a pre-existing IPA image is not
+build a Debian stretch based IPA image, if a pre-existing IPA image is not
 present on disk.  If you wish to explicitly set a specific release to be
 passed to diskimage-create, then the setting ``dib_os_release`` can be set in
 addition to ``dib_os_element``.

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

@@ -59,9 +59,9 @@ dib_os_release can be utilized to set the DIB_RELEASE environment
 variable for semi-dynamic disk image creation by a user or the
 test script.  By default, it is not set, but an example if
 dib_os_element is set to ``debian``, then a user could choose
-the ``jessie`` release.
+the ``stretch`` release.
 
-dib_os_release: jessie
+dib_os_release: stretch
 
 All the other command-line options to disk-image-create or
 ramdisk-image-create can be used by the role. The following is a list

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

@@ -111,9 +111,9 @@
   set_fact:
     dib_packages_arg: "-p {{dib_packages}}"
   when: dib_packages is defined and dib_packages != ""
-- name: "Set default of Debian Jessie if building debian and not explicitly set, overwride with dib_os_release setting"
+- name: "Set default of Debian Stretch if building debian and not explicitly set, overwride with dib_os_release setting"
   set_fact:
-    dib_os_release: "jessie"
+    dib_os_release: "stretch"
   when: dib_os_element == "debian" and dib_os_release is undefined
 - name: "Initialize the DIB environment variables fact"
   set_fact:

playbooks/test-bifrost.yaml

@@ -77,9 +77,9 @@
     # NOTE(TheJulia): While the next step creates a ramdisk, some elements
     # do not support ramdisk-image-create as they invoke steps to cleanup
     # the ramdisk which causes ramdisk-image-create to believe it failed.
-    - { role: bifrost-create-dib-image, dib_imagename: "{{ http_boot_folder }}/ipa", build_ramdisk: false, dib_os_element: "{{ ipa_dib_os_element|default('debian') }}", dib_os_release: "jessie", dib_elements: "ironic-agent {{ ipa_extra_dib_elements | default('') }}", dib_packages: "bsdmainutils", when: create_ipa_image | bool == true }
+    - { role: bifrost-create-dib-image, dib_imagename: "{{ http_boot_folder }}/ipa", build_ramdisk: false, dib_os_element: "{{ ipa_dib_os_element|default('debian') }}", dib_os_release: "stretch", dib_elements: "ironic-agent {{ ipa_extra_dib_elements | default('') }}", dib_packages: "bsdmainutils", when: create_ipa_image | bool == true }
     # NOTE(TheJulia): This creates the guest image.
-    - { role: bifrost-create-dib-image, dib_imagetype: "qcow2", dib_imagename: "{{deploy_image}}", dib_os_element: "debian", dib_os_release: "jessie", dib_elements: "vm enable-serial-console simple-init {{ extra_dib_elements|default('') }}", when: create_image_via_dib | bool == true and transform_boot_image | bool == false }
+    - { role: bifrost-create-dib-image, dib_imagetype: "qcow2", dib_imagename: "{{deploy_image}}", dib_os_element: "debian", dib_os_release: "stretch", dib_elements: "vm enable-serial-console simple-init {{ extra_dib_elements|default('') }}", when: create_image_via_dib | bool == true and transform_boot_image | bool == false }
     - role: bifrost-keystone-client-config
       user: "{{ ansible_env.SUDO_USER | default(ansible_user_id) }}"
       clouds:

releasenotes/notes/jessie-to-stretch-207bbd4f10149b4e.yaml

@@ -0,0 +1,9 @@
+---
+upgrade:
+  - |
+    The image building with ``diskimage-builder`` now uses Debian Stretch
+    by default, and all CI testing has been switched to it as well.
+fixes:
+  - |
+    Fixes building images with ``diskimage-builder`` by switching to Debian
+    Stretch (from Jessie).