Check if key exists in a dict in Jinja2 template on ansible

Question

I have a host_var in ansible with dict with all interfaces:

--- interfaces:   vlan0:     ip: 127.0.0.1     mask: 255.255.255.0     state: true    vlan2:     ip: 127.0.1.1     mask: 255.255.255.0     state: true 

And I want to check if dict has a key vlan1 if ok put to template value vlan1.ip else put vlan2.ip.

{% if interfaces.vlan1 %}  # and also I try {% if 'vlan1' in interfaces %} {{ interfaces.vlan1.ip }}; {% else %} {{ interfaces.vlan2.ip|default("127.0.0.1") }}; {% endif %}; 

But i have an error:

fatal: [127.0.0.1] => {'msg': "AnsibleUndefinedVariable: One or more undefined variables: 'dict object' has no attribute 'vlan1'", 'failed': True} 

I found that it have to be work in Jinja2 but it seems to doesn't work in ansible. Maybe someone have another way for solving this problem? When I define vlan1 it works fine. Ansible version 1.9.2

I was trying to reproduce it in python and have no error if my dictionary have not key vlan1. thanks to @GUIDO

>>> from jinja2 import Template >>> b = Template(""" ... {% if interfaces.vlan1 %} ... {{ interfaces.vlan1.ip }} ... {% else %} ... {{ interfaces.vlan2.ip|default("127.0.3.1") }} ... {% endif %}""") >>> b.render(interfaces={'vlan3':{'ip':'127.0.1.1'},'vlan2':{'ip':'127.0.2.1'}}) u'\n\n127.0.2.1\n' >>> b.render(interfaces={'vlan1':{'ip':'127.0.1.1'},'vlan2':{'ip':'127.0.2.1'}}) u'\n\n127.0.1.1\n' 

Answer 1

The answer is simple and it showed on ansible error message. First of all I need to check if var is defined.

{% if interfaces.vlan1 is defined %} {{ interfaces.vlan1.ip }} {% else %} {{ interfaces.vlan2.ip|default("127.0.3.1") }} {% endif %} 

This combination works well.