build-docker-image: fix up siblings copy

There are a number of issues with this.  Firstly, it needs to copy the
parent directories to make a heirarchy in the .zuul-siblings
directory.  The current "cp -r" was only copying the final directory.
Switch into the source directory and use "--parent" to do this.

Also, it should be copying into the context dir.  Add the
{{ item.context }} to the path where appropriate.

Also print out ZUUL_SIBLINGS in the Dockerfile so we can see it being
set.

Expand the testing to make a directory heirarchy, and test the copy
with asserts.

Change-Id: I9f3b0a1f71d20cf7511f224648dd2fa51a039015

roles/build-docker-image/tasks/build.yaml

@@ -1,6 +1,6 @@
 - name: Check sibling directory
   stat:
-    path: '{{ zuul_work_dir }}/.zuul-siblings'
+    path: '{{ zuul_work_dir }}/{{ item.context }}/.zuul-siblings'
   register: _dot_zuul_siblings
 
 # This should have been cleaned up; multiple builds may specify
@@ -11,7 +11,7 @@
 
 - name: Create sibling source directory
   file:
-    path: '{{ zuul_work_dir }}/.zuul-siblings'
+    path: '{{ zuul_work_dir }}/{{ item.context }}/.zuul-siblings'
     state: directory
     mode: 0755
   when: item.siblings is defined
@@ -19,7 +19,9 @@
 # NOTE(ianw): could use recursive copy: with remote_src, but it's
 # Ansible 2.8 only.  take the simple approach.
 - name: Copy sibling source directories
-  command: 'cp -r ~/src/{{ sibling }} {{ zuul_work_dir }}/.zuul-siblings/'
+  command:
+    cmd: 'cp --parents -r {{ sibling }} /home/zuul/{{ zuul_work_dir }}/{{ item.context }}/.zuul-siblings'
+    chdir: '~/src'
   loop: '{{ item.siblings }}'
   loop_control:
     loop_var: sibling

test-playbooks/registry/docker/Dockerfile

@@ -1,2 +1,4 @@
 FROM debian:testing
+ARG ZUUL_SIBLINGS=""
+CMD echo "Zuul siblings: ${ZUUL_SIBLINGS}"
 CMD echo "Zuul container test"; sleep infinity

test-playbooks/registry/test-registry.yaml

@@ -126,10 +126,10 @@
 
     - name: Create fake sibling projects
       command: >-
-        mkdir -p src/opendev.org/fake-sibling-1 &&
-        mkdir -p src/opendev.org/fake-sibling-2 &&
-        touch  src/opendev.org/fake-sibling-1/file &&
-        touch  src/opendev.org/fake-sibling-2/file
+        mkdir -p src/opendev.org/project/fake-sibling &&
+        mkdir -p src/openstack.org/project/fake-sibling &&
+        touch  src/opendev.org/project/fake-sibling/file &&
+        touch  src/openstack.org/project/fake-sibling/file
 
     - name: Build docker image
       include_role:
@@ -139,8 +139,23 @@
           - context: test-playbooks/registry/docker
             repository: downstream/image
             siblings:
-              - opendev.org/fake-sibling-1
-              - opendev.org/fake-sibling-2
+              - opendev.org/project/fake-sibling
+              - openstack.org/project/fake-sibling
+
+    - name: Check sibling copy 1 worked
+      stat:
+        path: test-playbooks/registry/docker/.zuul-siblings/opendev.org/project/fake-sibling/file
+      register: _sibling_copy_1
+
+    - name: Check sibling copy 2 worked
+      stat:
+        path: test-playbooks/registry/docker/.zuul-siblings/openstack.org/project/fake-sibling/file
+      register: _sibling_copy_2
+
+    - name: Assert copy worked
+      assert:
+        that: _sibling_copy_1.stat.exists and _sibling_copy_2.stat.exists
+
 
 - hosts: executor
   name: Test pushing to the intermediate registry