Ansible role for data presistence and restoration

This can be used for temporary persisting data on undercloud if we
want to reprovision the overcloud nodes.

Change-Id: If059c477cb2d344fa4c00ce4ea89269c4ef747bd
Implements: blueprint upgrades-with-os

roles/tripleo-persist/README.md

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+tripleo-persist
+===============
+
+An Ansible role to temporary persist a files on undercloud and later
+restore them.
+
+Role variables
+--------------
+
+Required:
+
+* `tripleo_persist_dir` -- directory on the target host to persist
+
+Optional:
+
+* `tripleo_persist_storage_root_dir` -- directory on the Ansible host
+  under which all data is stored
+  (defaults to "/var/lib/mistral/tripleo-persist")
+* `tripleo_persist_storage_root_become` -- whether to use `become`
+  when creating the storage root directory
+  (defaults to false)
+
+Test playbook
+-------------
+
+Assuming you have tripleo-inventory.yml generated, you can run the
+test playbook like:
+
+    ANSIBLE_ROLES_PATH=tripleo-common/roles \
+    ANSIBLE_HOST_KEY_CHECKING=False \
+    ansible-playbook
+        -i tripleo-inventory.yml \
+        tripleo-common/roles/tripleo-persist/test-playbook.yml \
+        -e persist=true
+
+    ANSIBLE_ROLES_PATH=tripleo-common/roles \
+    ANSIBLE_HOST_KEY_CHECKING=False \
+    ansible-playbook
+        -i tripleo-inventory.yml \
+        tripleo-common/roles/tripleo-persist/test-playbook.yml \
+        -e restore=true
+
+License
+-------
+
+Free software: Apache License (2.0)
+
+Author Information
+------------------
+
+OpenStack TripleO team

roles/tripleo-persist/defaults/main.yml

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+tripleo_persist_storage_root_dir: /var/lib/mistral/tripleo-persist
+tripleo_persist_storage_root_become: false

roles/tripleo-persist/tasks/persist.yml

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+- name: ensure local storage directory exists and has correct permissions
+  file:
+    path: "{{tripleo_persist_storage_root_dir}}"
+    # Attempting to set an owner fails with "chown failed: failed to
+    # look up user" so we at least ensure the permissions.
+    mode: 0700
+    state: directory
+  delegate_to: localhost
+  become: "{{tripleo_persist_storage_root_become}}"
+
+- name: create tempfile for the archive
+  tempfile:
+    prefix: ansible.tripleo-persist.
+  register: tripleo_persist_tempfile
+
+# Using the "archive" module lists lists all tarred files in module
+# output, if there's too many files, it can crash ansible even with
+# "no_log: true".
+- name: create the archive
+  shell: |
+    tar -czf "{{tripleo_persist_tempfile.path}}" -C "{{tripleo_persist_dir|dirname}}" "{{tripleo_persist_dir|basename}}"
+
+- name: fetch the archive
+  fetch:
+    src: "{{tripleo_persist_tempfile.path}}"
+    dest: "{{tripleo_persist_storage_root_dir}}/{{inventory_hostname}}{{tripleo_persist_dir}}.tar.gz"
+    flat: yes
+
+- name: remove tempfile
+  file:
+    name: "{{tripleo_persist_tempfile.path}}"
+    state: absent

roles/tripleo-persist/tasks/restore.yml

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+- name: make sure the parent directory is present
+  file:
+    path: "{{tripleo_persist_dir|dirname}}"
+    state: directory
+
+- name: push and extract the archive
+  unarchive:
+    src: "{{tripleo_persist_storage_root_dir}}/{{inventory_hostname}}{{tripleo_persist_dir}}.tar.gz"
+    dest: "{{tripleo_persist_dir|dirname}}"

roles/tripleo-persist/test-playbook.yml

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+- hosts: overcloud-controller-0
+  become: true
+  tasks:
+    - name: test tripleo-persist persistence
+      include_role:
+        name: tripleo-persist
+        tasks_from: persist.yml
+      vars:
+        tripleo_persist_dir: /testdir/testsubdir
+        tripleo_persist_storage_root_dir: /home/stack/tripleo-persist
+      when: persist|default(false)|bool
+
+    - name: test tripleo-persist restoration
+      include_role:
+        name: tripleo-persist
+        tasks_from: restore.yml
+      vars:
+        tripleo_persist_dir: /testdir/testsubdir
+        tripleo_persist_storage_root_dir: /home/stack/tripleo-persist
+      when: restore|default(false)|bool