Set up siblings dirs for each build in the loop

The buildx patch unfortunately changed the logic associated with
siblings to set up siblings in a loop one time, rather than to
do a loop of "set up siblings, build, cleanup siblings". This causes
builds to fail when they're using siblings with an error about
siblings dir not having been cleaned up.

Change-Id: I3c45bfa77ec9f2609689e04044c18f066adc9741

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

@@ -50,5 +50,5 @@
 
 - name: Cleanup sibling source directory
   file:
-    path: '{{ zuul_work_dir }}/.zuul-siblings'
+    path: '{{ zuul_work_dir }}/{{ zj_image.context }}/.zuul-siblings'
     state: absent

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

@@ -1,3 +1,6 @@
+- name: Set up siblings
+  include_tasks: siblings.yaml
+
 - name: Build a docker image
   command: >-
     docker build {{ zj_image.path | default('.') }} -f {{ zj_image.dockerfile | default(docker_dockerfile) }}
@@ -23,3 +26,6 @@
     --label "org.zuul-ci.change_url={{ zuul.change_url }}"
   args:
     chdir: "{{ zuul_work_dir }}/{{ zj_image.context }}"
+
+- name: Cleanup sibling source directory
+  include_tasks: clean-siblings.yaml

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

@@ -1,3 +1,6 @@
+- name: Set up siblings
+  include_tasks: siblings.yaml
+
 - name: Build a docker image
   command: >-
     docker buildx build {{ zj_image.path | default('.') }} -f {{ zj_image.dockerfile | default(docker_dockerfile) }}
@@ -34,3 +37,6 @@
   loop: "{{ zj_image.tags | default(['latest']) }}"
   loop_control:
     loop_var: zj_image_tag
+
+- name: Cleanup sibling source directory
+  include_tasks: clean-siblings.yaml

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

@@ -0,0 +1,4 @@
+- name: Cleanup sibling source directory
+  file:
+    path: '{{ zuul_work_dir }}/{{ zj_image.context }}/.zuul-siblings'
+    state: absent

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

@@ -14,12 +14,6 @@
     - result_json_stat.stat.size > 0
     - "'buildset_registry' in (lookup('file', zuul.executor.work_root + '/results.json') | from_json)"
 
-- name: Set up siblings
-  include_tasks: siblings.yaml
-  loop: "{{ docker_images }}"
-  loop_control:
-    loop_var: zj_image
-
 # Docker doesn't understand docker push [1234:5678::]:5000/image/path:tag
 # so we set up /etc/hosts with a registry alias name to support ipv6 and 4.
 - name: Configure /etc/hosts for buildset_registry to workaround docker not understanding ipv6 addresses

test-playbooks/registry/docker-siblings/Dockerfile

@@ -1,7 +1,10 @@
-FROM docker.io/upstream/image
+FROM docker.io/upstream/image as first
 ARG ZUUL_SIBLINGS=""
 RUN echo "Zuul siblings: ${ZUUL_SIBLINGS}"
 RUN cp /test-nonce /test-nonce-is-there
 COPY .zuul-siblings/opendev.org/project/fake-sibling/file /target
 COPY .zuul-siblings/openstack.org/project/fake-sibling/file /target
 CMD echo "Zuul container test"; sleep infinity
+
+FROM first as second
+RUN echo "This is just to test that loops with siblings work"

test-playbooks/registry/test-registry.yaml

@@ -140,9 +140,24 @@
             siblings:
               - opendev.org/project/fake-sibling
               - openstack.org/project/fake-sibling
+            target: first
+          - context: test-playbooks/registry/docker-siblings
+            repository: downstream/image2
+            target: second
+            siblings:
+              - opendev.org/project/fake-sibling
+              - openstack.org/project/fake-sibling
         _arch_docker_images:
           - context: test-playbooks/registry/docker-siblings
             repository: downstream/image
+            target: first
+            siblings:
+              - opendev.org/project/fake-sibling
+              - openstack.org/project/fake-sibling
+            arch: ['linux/amd64', 'linux/arm64']
+          - context: test-playbooks/registry/docker-siblings
+            repository: downstream/image2
+            target: second
             siblings:
               - opendev.org/project/fake-sibling
               - openstack.org/project/fake-sibling