B&R: Add playbook to restore user images

Add role for restoring registry images from docker archive.
Import user images from docker archive to docker.
Push the images referencing local registry. After the push the images
tags will be deleted. If there are no tags pointing to the same image
unique id the image will be deleted from the docker filesystem thus
recovering the space.

Partition where archive is located, docker partition, local registry
partition must all be big enough.

The archive can be bigger than available space before bootstrap
playbook is played. Restore platform procedure needs to be called before
restoring docker images so that bootstrap playbook is called and space
allocated.

For local plays there are 2 key variables, while for remote play there
are 4.
Var `initial_backup_dir` points to the directory where the backup file is
located.
Var `backup_filename` points to the file in the directory.
Var `backup_dir` is used for remote plays and is the destination folder
on the remote where the file will be copied.
Var `ansible_remote_tmp` points to a temporary directory on the remote
that ansible `copy` module will use to transfer the file.

Directories pointed to by `initial_backup_dir, `backup_dir` and
`ansible_remote_tmp` must be mounted where free space exceeds backup
size.

Example call:
restor_user_images.yml \
    -e "initial_backup_dir=/host1/sufficient/space1/" \
    -e "backup_filename=example.tar" \
    -e "ansible_remote_tmp=/host2/sufficient/space1/" \
    -e "backup_dir=/host2/sufficient/space1/"

Closes-Bug: 1886152
Depends-On: I4644784ea4164134f163d218e69dc4ceb148985a
Change-Id: I0a7dcf9d174fbc07af85ef51bb4068d0dc16c560
Signed-off-by: Dan Voiculeasa <dan.voiculeasa@windriver.com>

playbookconfig/src/playbooks/restore_user_images.yml

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+---
+#
+# Copyright (c) 2020 Wind River Systems, Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+- hosts: all
+  gather_facts: no
+
+  vars_files:
+    - host_vars/backup-restore/default.yml
+
+  roles:
+    - { role: common/prepare-env }
+    - { role: restore-user-images/prepare-env, become: yes }
+    - { role: backup-restore/prepare-env }
+    - { role: backup-restore/transfer-file }
+    - { role: restore-user-images/restore-local-registry-images, become: yes,
+        docker_images_backup: "{{ target_backup_dir }}/{{ backup_filename }}" }

playbookconfig/src/playbooks/roles/restore-user-images/prepare-env/tasks/main.yml

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+---
+#
+# Copyright (c) 2020 Wind River Systems, Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# ROLE DESCRIPTION:
+#   This role verifies if user images restore should proceed
+#
+- name: Fail if backup_filename is not defined or set
+  fail:
+    msg: "Mandatory configuration parameter backup_filename is not defined or set."
+  when: backup_filename is not defined or backup_filename is none
+
+- name: Fail if initial_backup_dir is not defined or set
+  fail:
+    msg: "Mandatory configuration parameter initial_backup_dir is not defined or set."
+  when: initial_backup_dir is not defined or initial_backup_dir is none
+
+- name: Check if restoring user images is already in progress
+  stat:
+    path: "{{ restore_user_images_in_progress_flag }}"
+  register: restore_user_images_in_progress
+
+- name: Fail if restoring user images is already in progress
+  fail:
+    msg: "Restoring user images is already in progress!"
+  when: restore_user_images_in_progress.stat.exists
+
+- name: Create {{ restore_user_images_in_progress_flag }} flag file
+  file:
+    path: "{{ restore_user_images_in_progress_flag }}"
+    state: touch
+
+- name: For remote play set target_backup_dir to {{ backup_dir }}
+  set_fact:
+    target_backup_dir: "{{ backup_dir }}"
+  when: inventory_hostname != "localhost"
+
+- name: For local play set target_backup_dir to initial_backup_dir
+  set_fact:
+    target_backup_dir: "{{ initial_backup_dir }}"
+  when: inventory_hostname == "localhost"

playbookconfig/src/playbooks/roles/restore-user-images/restore-local-registry-images/tasks/main.yml

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+---
+#
+# Copyright (c) 2020 Wind River Systems, Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# ROLE DESCRIPTION:
+#   This role exists to import container images from an archive.
+#   It pushes images starting with `registry.local:9001`, thus
+#   the images meant to be pushed to local registry.
+#
+
+- block:
+    - name: Check that backup archive exists
+      stat:
+        path: "{{ docker_images_backup }}"
+      register: file_result
+
+    - block:
+        - name: Import docker images
+          command: docker load -i {{ docker_images_backup }}
+
+        - name: Get image list to push to local registry
+          shell: docker image ls | grep -s '^registry.local:9001' | awk -F' ' '{print($1":"$2)}'
+          register: image_list_query
+
+        - debug: var=image_list_query.stdout_lines
+
+        - name: Push to local registry if any image tagged as such
+          script: >
+            roles/common/push-docker-images/files/push_pull_local_registry.py push \
+              "{{ image_list_query.stdout_lines | join(',') }}"
+          when: image_list_query.stdout_lines|length > 0
+
+      when: file_result.stat.exists
+
+  when: docker_images_backup is defined
+
+  always:
+    - name: Remove the {{ restore_user_images_in_progress_flag }} file
+      file:
+        path: "{{ restore_user_images_in_progress_flag }}"
+        state: absent

playbookconfig/src/playbooks/roles/restore-user-images/restore-local-registry-images/vars/main.yml

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+---
+#
+# Copyright (c) 2019 Wind River Systems, Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+# Flag file to indicate if user images restore is in progress
+#
+restore_user_images_in_progress_flag: /etc/platform/.restore_user_images_in_progress