Intersection of group variables inside a Jinja template.

[Ehtesh Choudhury]

I'm using ec2.py as my hostfile and I'm writing the following templating in
Jinja2.

    {% for host in groups["tag_provides_logstash-server"] %}
    # {{ hostvars[host]["ec2_ip_address"] }} {{ hostvars[host]["ec2_tag_Name"] }}
    {% endfor %}

    # This isn't valid in Jinja2, but is what I"m looking for:
    # groups["tag_provides_logstash-server:&tag_env_dev"]

Other people have aimed for this behavior before:

    https://groups.google.com/forum/#!topic/Ansible-project/QuqXUV_BEMM

Gustavo's resolution isn't as simple as I would like, though.
This is what I have settled on for now:

    {% for host in groups["tag_provides_logstash-server"] | intersect(groups["tag_env_dev"]) %}
    # {{ hostvars[host]["ec2_ip_address"] }} {{ hostvars[host]["ec2_tag_Name"] }}
    {% endfor %}

It looks good, but I would like to know if there's anything grossly wrong or
devious with this approach.

[Michael DeHaan]

In your template above I'd probably just assign a "my_hosts" variable to the expression to clean up the loop a bit.

{# set my_hosts = groups["tag_provides_logstash-server"] | intersect(groups["tag_env_dev"]) #}

{% for host in my_hosts %}

etc

The other thing you have is the "play_hosts" variable in Ansible which should return all the hosts in the current play.

So to your question, yes, there are easier ways now that can make things easier to follow.

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[Mark Maas]

Gents,

Could you elaborate a bit on how to use this?

You see, i’m trying to do the same thing:

# Cluster connection URL 
{# set mysql_hosts = groups["tag_type_mysql"] | intersect(groups["tag_environment_dev"]) #}
wsrep_cluster_address=gcomm://{% for host in mysql_hosts %}{{ hostvars[host]['ansible_eth0']['ipv4']['address'] }},{% endfor %}

But the variable “mysql_hosts” does not seem to get populated:

fatal: [10.220.226.243] => {'msg': "AnsibleUndefinedVariable: One or more undefined variables: 'mysql_hosts' is undefined", 'failed': True

When I look at the two groups:

type mysql group
{{ groups.tag_type_mysql | to_nice_yaml }}
env dev group
{{ groups.tag_environment_dev | to_nice_yaml }}

They result in:

type mysql group

- 10.220.226.243
- 10.220.227.5
- 10.220.225.203
env dev group

- 10.220.2.242
- 10.220.3.129
- 10.220.227.77
- 10.220.222.24
- 10.220.221.8
- 10.220.226.9
- 10.220.226.243
- 10.220.226.70
- 10.220.227.5
- 10.220.225.203
- 10.220.227.20
- 10.220.1.169
- 10.220.225.84
- 10.220.220.247
- 10.220.225.126

so I know they exist and are filled..

Thanks for looking!

[Matt Martz]

I think there was a typo, instead of using {# #} you should probably be using {% %}

The {# #} characters indicate a jinja2 comment.

To view this discussion on the web visit https://groups.google.com/d/msgid/ansible-project/13d3a708-dd40-417c-87fb-c466df921974%40googlegroups.com.

For more options, visit https://groups.google.com/d/optout.

--

Matt Martz
@sivel
sivel.net