use {obj:key} as a way to pass an object and not only strings to templates

As mentioned at the mail list[0]:

"So I need another way how to pass a *list* as data structure from
the defaults/project down to the job-template definition, similar to
what can be done with "{variable}" for strings."

[0] http://lists.openstack.org/pipermail/openstack-infra/2014-February/000799.html

Closes-Bug: 1281038
Change-Id: I5b04ddb52e537fedd2d05795e91011afd92f2295

doc/source/configuration.rst

@@ -123,6 +123,12 @@ define a template that you can use to create jobs with a `Project`_
 definition.  It's name will depend on what is supplied to the
 `Project`_.
 
+If you want to use lists or dicts variables you can use ``{obj:key}``.
+
+For example:
+
+.. literalinclude::  /../../tests/yamlparser/fixtures/custom_distri.yaml
+
 .. _project:
 
 Project

jenkins_jobs/builder.py

@@ -79,7 +79,11 @@ def deep_format(obj, paramdict):
     # example, is problematic).
     if isinstance(obj, str):
         try:
-            ret = obj.format(**paramdict)
+            result = re.match('^{obj:(?P<key>\w+)}$', obj)
+            if result is not None:
+                ret = paramdict[result.group("key")]
+            else:
+                ret = obj.format(**paramdict)
         except KeyError as exc:
             missing_key = exc.message
             desc = "%s parameter missing to format %s\nGiven: %s" % (

tests/yamlparser/fixtures/custom_distri.xml

@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="utf-8"?>
+<matrix-project>
+  <executionStrategy class="hudson.matrix.DefaultMatrixExecutionStrategyImpl">
+    <runSequentially>false</runSequentially>
+  </executionStrategy>
+  <combinationFilter/>
+  <axes>
+    <hudson.matrix.TextAxis>
+      <name>distribution</name>
+      <values>
+        <string>precise</string>
+        <string>jessie</string>
+      </values>
+    </hudson.matrix.TextAxis>
+    <hudson.matrix.TextAxis>
+      <name>architectures</name>
+      <values>
+        <string>amd64</string>
+        <string>i386</string>
+      </values>
+    </hudson.matrix.TextAxis>
+  </axes>
+  <actions/>
+  <description>&lt;!-- Managed by Jenkins Job Builder --&gt;</description>
+  <keepDependencies>false</keepDependencies>
+  <blockBuildWhenDownstreamBuilding>false</blockBuildWhenDownstreamBuilding>
+  <blockBuildWhenUpstreamBuilding>false</blockBuildWhenUpstreamBuilding>
+  <concurrentBuild>false</concurrentBuild>
+  <canRoam>true</canRoam>
+  <properties/>
+  <scm class="hudson.scm.NullSCM"/>
+  <builders/>
+  <publishers/>
+  <buildWrappers/>
+</matrix-project>

tests/yamlparser/fixtures/custom_distri.yaml

@@ -0,0 +1,22 @@
+- project:
+    name: test_custom_distri
+    distributions: !!python/tuple [precise, jessie]
+    architectures: !!python/tuple &architectures
+      - amd64
+      - i386
+    axis_a:
+        type: user-defined
+        name: architectures
+        values: *architectures
+    jobs:
+      - '{name}-source'
+
+- job-template:
+      name: '{name}-source'
+      project-type: matrix
+      axes:
+        - axis:
+            type: user-defined
+            name: distribution
+            values: '{obj:distributions}'
+        - axis: '{obj:axis_a}'