Creating name of inventory group from a variable

[ajres]

I have a task where I am updating a line in a file with a comma separated list of inventory hosts, this works for the hard coded case:

- name: Set host list
    lineinfile: dest=/home/project/pom.xml regexp='<targetHosts>.*</targetHosts>' line='<targetHosts>{{ groups.tag_Type_targettype | intersect('groups.key_mykey) | join(', ') }}</targetHosts>'

key_mykey is a group generated from ec2 properties in a dynamic inventory using:

  - name: Create groups based on ec2 access key

    group_by: key=key_{{ ec2_key_name }}

The issue I'm facing is that I need to be able to generate the intersection 'key_<MYKEY>' from a variable so that I can generate different intersections at playbook runtime.

I have tried different ways to use a variable for <MYKEY>, most give a runtime error, the following does not, but it also generates an empty hosts list.

  vars:

    ec2keyname: mykey

intersect('groups.key_' + ec2keyname)

Is there a way to use a variable in the intersection groups name?

Andy

[ajres]

The solution turned out to be simply to use variable bracket notation instead of dot notation, the value in the brackets can be formed from the concatenation of a string and a variable

line='<targetHosts>{{ groups.tag_Type_syncgateway | intersect(groups[key_' + ec2keyname]) | join(',') }}</targetHosts>'