helm-template: enable using values file

This patch allows the user to use a provided values file when running
the helm-template role.

Change-Id: I8e0988c8ec58a33228a326145458a9a0fca323a0

roles/helm-template/README.rst

@@ -17,6 +17,10 @@ already setup and the Helm executable is installed.
    Determine if the role should wait for all pods to go up after it applies
    the template.
 
+.. zuul:rolevar:: helm_values_file
+
+   File containing Helm values to use when templating.
+
 .. zuul:rolevar:: zuul_work_dir
    :default: {{ zuul.project.src_dir }}
 

roles/helm-template/tasks/main.yaml

@@ -11,7 +11,7 @@
 - name: Deploy templated charts
   shell: |
     set -o pipefail
-    helm template -n {{ helm_release_name }} {{ helm_chart }} | kubectl apply -f-
+    helm template {% if helm_values_file %}--values {{ helm_values_file }} {% endif %}-n {{ helm_release_name }} {{ helm_chart }} | kubectl apply -f-
   args:
     executable: /bin/bash
     chdir: "{{ zuul_work_dir }}"