Zuul v3: Add use-cached-repos role

This adds a role to clone the cached repos into the workspace,
and alters base-test to use it as well as follow-up roles to
synchronize their states and start zuul_console, instead of the
default prepare-workspace role which uses rsync and is less
efficient.

Change-Id: Ifb0fedf1df1d50444ecb1f3fb03f21b112c9dad9
Depends-On: Ib50ddff0198411e7cd5857d5bfbb915f02baadf1

playbooks/base-test/pre.yaml

@@ -1,7 +1,9 @@
 - hosts: all
   roles:
     - add-build-sshkey
-    - prepare-workspace
+    - start-zuul-console
+    - use-cached-repos
+    - mirror-workspace-git-repos
     - role: validate-host
       # TODO(mordred) When we have site-local variables, these should go there
       zuul_traceroute_host: git.openstack.org

roles/use-cached-repos/README.rst

@@ -0,0 +1,9 @@
+Clone repos from the image cache into the workspace
+
+Clon any repos cached on the remote node (via the image build process)
+that this job uses into the workspace.  If a repo doesn't exist, clone
+it from its source.
+
+These repos are neither up to date, nor do they contain the changes
+that Zuul has prepared.  A separate role should synchronize the local
+and remote repos.

roles/use-cached-repos/tasks/main.yaml

@@ -0,0 +1,26 @@
+- name: Find locally cached git repos
+  stat:
+    path: "/opt/git/{{ item.name }}"
+  with_items: "{{ zuul.projects }}"
+  register: cached_repos
+
+- name: Clone cached repo to workspace
+  command: "git clone /opt/git/{{ item.0.name }} {{ ansible_user_dir }}/{{ item.0.src_dir}}"
+  creates: "{{ ansible_user_dir }}/{{ item.0.src_dir}}"
+  when: item.1.stat.exists
+  with_together:
+    - " {{ zuul.projects }}"
+    - " {{ cached_repos }}"
+
+- name: Clone upstream repo to workspace
+  command: "git clone https://{{ item.0.canonical_hostname }}/{{ item.0.name}} {{ ansible_user_dir }}/{{ item.0.src_dir}}"
+  creates: "{{ ansible_user_dir }}/{{ item.0.src_dir}}"
+  when: not item.1.stat.exists
+  with_together:
+    - " {{ zuul.projects }}"
+    - " {{ cached_repos }}"
+
+- name: Remove origin from local git repos
+  command: "git remote rm origin"
+  chdir: "{{ ansible_user_dir }}/{{ item.src_dir}}"
+  with_items: " {{ zuul.projects }}"