Add a tag pipeline

And make the publications job handle running on tags and use the
tag pipeline.

Change-Id: Icdd02318c98c9650a8d8f186f573958ebf346afa

modules/openstack_project/files/jenkins_job_builder/config/infra-publications.yaml

@@ -6,13 +6,19 @@
 
     builders:
       - gerrit-git-prep
+      - shell: |
+          #!/bin/bash -x
+          # NAME will either be the branch name or the tag name
+          NAME=`echo $ZUUL_REFNAME | sed 's/refs.tags.//'`
+          mkdir -p _out/$NAME
+          mv * _out/$NAME
 
     publishers:
       - ftp:
           site: docs.openstack.org
-          source: '**'
-          target: 'infra/publications/$ZUUL_REF/'
-          remove-prefix: ''
+          source: '_out/**'
+          target: 'infra/publications/'
+          remove-prefix: '_out/'
           excludes: ''
       - console-log
 

modules/openstack_project/files/zuul/layout.yaml

@@ -52,6 +52,15 @@ pipelines:
         - event: ref-updated
           ref: ^(?!(devnull|refs/.*)).*$
 
+  - name: tag
+    description: This pipeline runs jobs in response to any tag event.
+    manager: IndependentPipelineManager
+    precedence: high
+    trigger:
+      gerrit:
+        - event: ref-updated
+          ref: ^refs/tags/.*$
+
   - name: pre-release
     description: This pipeline runs jobs on projects in response to pre-release tags.
     manager: IndependentPipelineManager
@@ -2435,6 +2444,9 @@ projects:
     post:
       - infra-publications-publish
       - infra-publications-publish-index
+    tag:
+      - infra-publications-publish
+      - infra-publications-publish-index
 
   - name: openstack-infra/puppet-apparmor
     check: