Conditional master credentials
diff --git a/jenkins/files/_jenkins.conf b/jenkins/files/_jenkins.conf
index 4d716a1..42cf6fd 100644
--- a/jenkins/files/_jenkins.conf
+++ b/jenkins/files/_jenkins.conf
@@ -1,5 +1,7 @@
 {%- from "jenkins/map.jinja" import client with context %}
 jenkins:
   url: "{{ client.master.get('proto', 'http') }}://{{ client.master.host }}:{{ client.master.port }}"
+  {%- if client.master.username is defined %}
   user: {{ client.master.username }}
-  password: {{ client.master.password }}
\ No newline at end of file
+  password: {{ client.master.password }}
+  {%- endif %}
\ No newline at end of file