Otdfbt

I'm setting up a bunch of up to 150 temporary EC2 servers for a hands-on tutorial session.

I'm successfully creating EC2 inventory dynamically and running roles against the instances that are created to configure everything, but I need to set a straightforward hostname for each one. To that end I have a file that contains a simple list of names that I want to use for the hostnames. This is in my playbook:

---
- hosts: localhost
 connection: local
 gather_facts: false

 tasks:
 - name: Provision a set of instances
 ec2:
 key_name: ubuntu
 instance_type: t2.micro
 image: " ami_id "
 wait: true
 exact_count: server_count 
 count_tag:
 Name: Tutorial
 instance_tags:
 Name: Tutorial
 groups: ['SSH', 'Web']
 register: ec2

 - name: Add all instance public IPs to host group
 add_host: hostname= item.public_ip groups=ec2hosts
 loop: " ec2.instances "

 - name: Set a host name for each instance in DNS
 route53:
 zone: tutorial_domain 
 record: "name. tutorial_domain "
 state: present
 type: A
 ttl: 120
 value: item.public_ip 
 wait: yes
 loop: " ec2.instances "

It really comes down to that record: "name. tutorial_domain " line - how can I look up a name in my list of names and use it as a hostname, turning name into some_dynamic_name ?

I have seen the lookup plugins, but they all seem to be focused on looping over the entire contents of some external file - but I'm already looping over the list of servers, and that list may be shorter than the list of names (e.g. I may have only 10 servers). Ideally I want to read the list of names into an array once, then use the index from the server loop to pick the name (i.e. so the 3rd server would get the 3rd name). How do I do that in ansible? Or is there a better approach?

You can use the zip filter to combine your list of instances with a list of names, like this:

---
- hosts: localhost
 gather_facts: false
 vars:
 tutorial_domain: example.com
 ec2:
 instances:
 - public_ip: 1.2.3.4
 - public_ip: 2.3.4.5

 names:
 - blue-duck
 - red-panda

 tasks:
 - debug:
 msg:
 route53:
 zone: " tutorial_domain "
 record: " item.1 .tutorial_domain"
 state: present
 type: A
 ttl: 120
 value: " item.0.public_ip "
 wait: yes
 loop: "zip(names)"

In older versions of Ansible, you would accomplish the same thing with a with_together loop.