[ffwd] Allow users to replace environment files

A new option allows user to replace the content of specific
environment files which are listed in the "overcloud deploy"
bash script which is parsed and used here.

This is useful when the content of a file is known to
have changed between the source and destination release.
The feature is implemented for FFWD only right now,
but it could be used for any kind of upgrade/update process.

Change-Id: I027770e0ac8c73896d2b57218da3a5063b9707fd

infrared_plugin/plugin.spec

@@ -300,6 +300,13 @@ subparsers:
                       help: |
                           Fast Forward Upgrade compute nodes one by one
                       default: false
+                  overcloud-ffu-replace-env-files:
+                      type: KeyValueList
+                      help: |
+                          A comma-separated list of key/values which describe the environment files
+                          whose content should be replaced during the upgrade phase.
+                          The value must be the path to the new file, while the key must match
+                          the file name to replaced as it shows inside the deploy script.
             - title: Set up FFU packages
               options:
                   mirror:

tasks/common/replace_environment_file.yaml

@@ -0,0 +1,19 @@
+---
+- name: determine the name of the replaced environment file
+  shell:
+    cat {{ overcloud_deploy_script }} | grep '-e .\+{{ item.key }} ' |  sed 's/.\+ \(.\+{{ item.key }}\) .*/\1/'
+  register: ffu_replaced_env_file
+
+- block:
+    - name: save a copy of the replaced environment configuration file
+      copy:
+        remote_src: true
+        src: "{{ ffu_replaced_env_file.stdout }}"
+        dest: "{{ ffu_replaced_env_file.stdout }}.orig.yaml"
+
+    - name: replace the environment configuration file with the new one
+      copy:
+        src: "{{ item.value }}"
+        dest: "{{ ffu_replaced_env_file.stdout }}"
+
+  when: ffu_replaced_env_file.stdout|length > 0

tasks/common/replace_environment_files.yaml

@@ -0,0 +1,4 @@
+---
+- name: loop over the replacement environment configuration files
+  include_tasks: replace_environment_file.yaml
+  loop: "{{ install.overcloud.ffu.replace.env.files | default({}) | dict2items }}"

tasks/fast-forward-upgrade/main.yml

@@ -135,6 +135,10 @@
       import_tasks: convert_tls_templates.yaml
       tags: ffu_overcloud_prepare
 
+    - name: replace environment files
+      import_tasks: ../common/replace_environment_files.yaml
+      tags: ffu_overcloud_prepare
+
     - name: run overcloud upgrade prepare
       import_tasks: ../upgrade/overcloud_upgrade_prepare.yml
       tags: ffu_overcloud_prepare