Add diskimage-builder lint job

Add a "dib" tox environment to run "dib-lint", the linting tool
diskimage-builder runs over its included elements.

Add this as a non-voting job for now; there are issues in dib-lint and
our elements to sort out
(e.g. Ibba1dadb9e819f94294c9d583b83ff698252f93f, as a start).

Change-Id: I28459a9bbaaa6175d03dbe753498849a75942538

jenkins/jobs/infra.yaml

@@ -230,3 +230,17 @@
 
     publishers:
       - console-log
+
+
+- job:
+    name: gate-project-config-dib
+    node: 'bare-precise || bare-trusty'
+
+    builders:
+      - revoke-sudo
+      - gerrit-git-prep
+      - tox:
+          envlist: 'dib'
+
+    publishers:
+      - zuul-swift-upload-console-log

tox.ini

@@ -75,3 +75,11 @@ deps =
    Jinja2
    PyYAML
 commands = {toxinidir}/specs/generate_specs_site.py {toxinidir}/specs/specs.yaml
+
+[testenv:dib]
+# flake8 is missing from dib; see https://review.openstack.org/#/c/229780/
+deps =
+   diskimage-builder
+   flake8
+changedir = {toxinidir}/nodepool
+commands = dib-lint

zuul/layout.yaml

@@ -1794,6 +1794,9 @@ jobs:
 
   # End Constraints Jobs
 
+  - name: gate-project-config-dib
+    voting: false
+
 # The project list is grouped by type of project, and within each
 # group, projects are sorted (mostly) alphabetically.
 projects:
@@ -6120,6 +6123,7 @@ projects:
       - gate-project-config-projects-yaml
       - gate-infra-docs-index
       - gate-generate-specs-site
+      - gate-project-config-dib
     gate:
       - project-config-gerrit
       - gate-project-config-layout