Add devstack base job for zuul v3

This should be managed in the devstack repo, since it's a base job to
run devstack.

Change-Id: Iffe54fbccbccd68db08f79a1b51dd7f76dbff408
Depends-On: Ie2119f24360d56690ffd772b95a9ea6b98dd4a39
diff --git a/roles/setup-devstack-cache/README.rst b/roles/setup-devstack-cache/README.rst
new file mode 100644
index 0000000..b8938c3
--- /dev/null
+++ b/roles/setup-devstack-cache/README.rst
@@ -0,0 +1,15 @@
+Set up the devstack cache directory
+
+If the node has a cache of devstack image files, copy it into place.
+
+**Role Variables**
+
+.. zuul:rolevar:: devstack_base_dir
+   :default: /opt/stack
+
+   The devstack base directory.
+
+.. zuul:rolevar:: devstack_cache_dir
+   :default: /opt/cache
+
+   The directory with the cached files.
diff --git a/roles/setup-devstack-cache/defaults/main.yaml b/roles/setup-devstack-cache/defaults/main.yaml
new file mode 100644
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+++ b/roles/setup-devstack-cache/defaults/main.yaml
@@ -0,0 +1,2 @@
+devstack_base_dir: /opt/stack
+devstack_cache_dir: /opt/cache
diff --git a/roles/setup-devstack-cache/tasks/main.yaml b/roles/setup-devstack-cache/tasks/main.yaml
new file mode 100644
index 0000000..84f33f0
--- /dev/null
+++ b/roles/setup-devstack-cache/tasks/main.yaml
@@ -0,0 +1,14 @@
+- name: Copy cached devstack files
+  # This uses hard links to avoid using extra space.
+  command: "find {{ devstack_cache_dir }}/files -mindepth 1 -maxdepth 1 -exec cp -l {} {{ devstack_base_dir }}/devstack/files/ ;"
+  become: true
+
+- name: Set ownership of cached files
+  file:
+    path: '{{ devstack_base_dir }}/devstack/files'
+    state: directory
+    recurse: true
+    owner: stack
+    group: stack
+    mode: a+r
+  become: yes