Using ExtractValue from Integration Alias in a Task Template

[billglick]

I'm tying to setup an integration alias such that I can append ?host=foobar to my URL and have that run a task template with it limited to foobar. But, I can't figure out how to reference my ExtractValue variable in my task template.

In my integration I have the following for my Extract Value settings:

• Source of the value: Header
• Key: host
• Variable Usage: Task
• Variable: HOST_ALIAS
  The field for source of the value is the main thing I'm uncertain of here, but think this is correct.

But I am totally unclear how to reference the variable HOST_ALIAS in my task template so that it limits to that variable..

[billglick]

We got this to work by specifying the HOST_ALIAS variable in our playbook, e.g.

- name: "Site"
  # FOLLOWING IS A HACK TO LET US TARGET A SPECIFIC HOST VIA WEBHOOK INTEGRATION
  hosts: "{{ HOST_ALIAS | default('all') }}"
  roles:
    - "common"

I also had to change the Integration Extract Value to Variable Usage: Environment, and then calling the web hook via a curl command like the following:

curl -k -X POST \
  -H "Content-Type: application/json" \
  https://semaphore.local/api/integrations/ALIAS \
  -d "{\"host\":\"$(hostname -s)*\"}"