OP is @pkaramol - see ansible/ansible#33373 (closed by bot)

SUMMARY

Enable on-the-fly instance type change (upgrade / downgrade).

Currently when running a script that creates ec2 instance(s), there is no way to perform a type change (e.g. from t2.micro to t2.small).

ISSUE TYPE

• Feature Idea

COMPONENT NAME

ec2_instance (as proposed in original ticket - see ansible/ansible#33373 (comment))
or potentially a new module (as suggested here - ansible/ansible#33373 (comment))

ADDITIONAL INFORMATION

If you want to use Ansible to manage infrastructure then you need to be able to up and down grade EC2 instance type as part of that. Currently we need to use the CLI, which is simple enough, but it would be more elegant of Ansible just handled this.

Here's the OP again:

Using vars from below

     my_instances:
     - instance_type: "t2.micro"
       exact_count: "1"
       assign_public_ip: "no"
     - instance_type: "t2.micro"
       exact_count: "1"
       assign_public_ip: "no"

and running the following task based on those vars:

    - name: Create my instances
      ec2:
        instance_type: "{{ item.ec2_instance_type }}"
        region: "us-east-1"
        image: "some-image"
        group_id: "some-group-id"
        vpc_subnet_id: "some-subnet-id"
        instance_tags:
      with_items: "{{ my_instances }}"

if those instances are there and running and one wants to re-run the script, having one of the instance types changed (from t2.micro --> t2.small), e.g. as follows:

 - instance_type: "t2.small"

the script runs idempotently again, although the output yields:

ok: [localhost] => (item={instance_type': u't2.small'})

(output trimmed).

OP's point being he expected the instance size to change. There's some follow-up discussion between @ryansb and @bobobox about how this might be implemented, and a plan seems to be formed, specifically:

• User provides instance_type parameter, and if the instance does not exist it's created (as in ec2 module)
• User provides no instance_type parameter: no changes are made if the instance exists
• User provides an instance_type parameter that doesn't match:
  • If the instance is running, no change & the module displays a warning
  • If the instance is stopped, or desired state is stopped, then the instance is stopped& the type can be changed, relying on the user to follow up with a task to start the instance
  • If the instance is running, and a force: flag is set to true, then ec2_instance stops the instance, changes the type, and starts it back up.

And some specific concerns, which caused the suggestion the default behaviour ought not to be just blindly change instance type:

• ...changing an instance type can require numerous other changes as well: NVMe EBS volumes used on M5/C5 instances show up with different device names, enhanced networking and EBS optimization may need to be toggled appropriately, and of course the OS may or may not even boot successfully with a different instance type, depending on things like different virtual network adapters etc.

It's this complexity which makes the original participants consider that maybe this is a separate module entirely, as instance_type is already optional for ec2_instance.

Anyway, putting this back in as it feels valid and it seems to have been dropped.