diff --git a/doc/source/user/jobs.rst b/doc/source/user/jobs.rst
index 6962b8f66a..cf607b9f91 100644
--- a/doc/source/user/jobs.rst
+++ b/doc/source/user/jobs.rst
@@ -249,6 +249,13 @@ of item.
          A boolean indicating whether this project appears in the
          :attr:`job.required-projects` list for this job.
 
+   .. var:: _projects
+      :type: dict
+
+      The same as ``projects`` but a dictionary indexed by the
+      ``name`` value of each entry.  ``projects`` will be converted to
+      this.
+
    .. var:: tenant
 
       The name of the current Zuul tenant.
diff --git a/zuul/executor/client.py b/zuul/executor/client.py
index 041f754a8c..ae22c8ea7a 100644
--- a/zuul/executor/client.py
+++ b/zuul/executor/client.py
@@ -187,6 +187,7 @@ class ExecutorClient(object):
             and item.change.newrev != '0' * 40):
             zuul_params['newrev'] = item.change.newrev
         zuul_params['projects'] = []  # Set below
+        zuul_params['_projects'] = {}  # transitional to convert to dict
         zuul_params['items'] = []
         for i in all_items:
             d = dict()
@@ -270,14 +271,24 @@ class ExecutorClient(object):
                 projects.add(project)
 
         for p in projects:
-            zuul_params['projects'].append(dict(
+            zuul_params['_projects'][p.canonical_name] = (dict(
                 name=p.name,
                 short_name=p.name.split('/')[-1],
-                canonical_hostname=p.canonical_hostname,
+                # Duplicate this into the dict too, so that iterating
+                # project.values() is easier for callers
                 canonical_name=p.canonical_name,
+                canonical_hostname=p.canonical_hostname,
                 src_dir=os.path.join('src', p.canonical_name),
                 required=(p in required_projects),
             ))
+        # We are transitioning "projects" from a list to a dict
+        # indexed by canonical name, as it is much easier to access
+        # values in ansible.  Existing callers are converted to
+        # "_projects", then once "projects" is unused we switch it,
+        # then convert callers back.  Finally when "_projects" is
+        # unused it will be removed.
+        for cn, p in zuul_params['_projects'].items():
+            zuul_params['projects'].append(p)
 
         build = Build(job, uuid)
         build.parameters = params