sync-devstack-data: new argument devstack_data_base_dir

When the role is used by grenade, the data directory is shared among
different devstack executions, and the base directory is different,
for example: /opt/stack/data vs /opt/stack/{old,new}.
The new devstack_data_base_dir parameter allows user to specify
a base directory for the data/ directory which is unrelated
to the devstack directory. The default value is devstack_base_dir,
so the default behavior is unchanged.

Change-Id: Ie69b7b51947cbf1a8b31d2701783de2fb56a2d33

roles/sync-devstack-data/README.rst

@@ -10,3 +10,10 @@ subnodes.
    :default: /opt/stack
 
    The devstack base directory.
+
+.. zuul:rolevar:: devstack_data_base_dir
+   :default: {{ devstack_base_dir }}
+
+   The devstack base directory for data/.
+   Useful for example when multiple executions of devstack (i.e. grenade)
+   share the same data directory.

roles/sync-devstack-data/defaults/main.yaml

@@ -1 +1,2 @@
 devstack_base_dir: /opt/stack
+devstack_data_base_dir: "{{ devstack_base_dir }}"

roles/sync-devstack-data/tasks/main.yaml

@@ -1,7 +1,7 @@
 - name: Ensure the data folder exists
   become: true
   file:
-    path: "{{ devstack_base_dir }}/data"
+    path: "{{ devstack_data_base_dir }}/data"
     state: directory
     owner: stack
     group: stack
@@ -11,7 +11,7 @@
 - name: Ensure the CA folder exists
   become: true
   file:
-    path: "{{ devstack_base_dir }}/data/CA"
+    path: "{{ devstack_data_base_dir }}/data/CA"
     state: directory
     owner: stack
     group: stack
@@ -25,8 +25,8 @@
     dest: "{{ zuul.executor.work_root }}/{{ item | basename }}"
     mode: pull
   with_items:
-    - "{{ devstack_base_dir }}/data/ca-bundle.pem"
-    - "{{ devstack_base_dir }}/data/CA"
+    - "{{ devstack_data_base_dir }}/data/ca-bundle.pem"
+    - "{{ devstack_data_base_dir }}/data/CA"
   when: inventory_hostname == 'controller'
 
 - name: Push the CA certificate
@@ -34,7 +34,7 @@
   become_user: stack
   synchronize:
     src: "{{ zuul.executor.work_root }}/ca-bundle.pem"
-    dest: "{{ devstack_base_dir }}/data/ca-bundle.pem"
+    dest: "{{ devstack_data_base_dir }}/data/ca-bundle.pem"
     mode: push
   when: 'inventory_hostname in groups["subnode"]|default([])'
 
@@ -43,6 +43,6 @@
   become_user: stack
   synchronize:
     src: "{{ zuul.executor.work_root }}/CA/"
-    dest: "{{ devstack_base_dir }}/data/"
+    dest: "{{ devstack_data_base_dir }}/data/"
     mode: push
   when: 'inventory_hostname in groups["subnode"]|default([])'