hopefully quick question about jinja2 for loops and variables

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1

Hi all,

I am trying to iterate over a set of hosts in a jinja2 template almost exactly like this example from the Advanced Playbooks page:

{% for host in groups['app_servers'] %}
   {{ hostvars[host]['ansible_eth0']['ipv4']['address'] }}
{% endfor %}

the difference is in my example the group name is generated from a variable. So instead of a known string like ‘app_servers’ I have something like ‘app_type_$foo’. This syntax is not working and I never enter the for loop.

For debugging purposes I am creating a jinja2 variable

{% set group_name = app_type_{{ foo }}’ %}

and this is being set correctly, but I can’t figure out the syntax for referencing the variable I have set in the jinja2 for loop, which is likely a side affect of my Python !awesomeness

{% for host in groups[ ‘group_name’ ] %} doesn’t work, nor does

{% for host in groups[ group_name ] %}

I am hoping that this is possible, but I have a syntax issue.
any help would be most appreciated.

cheers,
Jonathan

2

I am not sure your set statement is right actually.

Instead of:

{% set group_name = app_type_{{ foo }}’ %}

I would do:

{% set group_name = ‘app_type’ + foo %}

And then in your loop, rather than doing ‘group_name’ you want the unquoted group_name:

{% for host in groups[ group_name ] %}

You should probably check what “group_name” got set to with your “set” statement and will probably find out it was not what you expected…

3

Works.

Not entirely sure how you ever actually write code due to your list contributions :slight_smile: Many thanks!