Resize EC2 instances using Ansible Tower.

resize_instance.yml

---

- hosts: all
  connection: local
  gather_facts: no

  pre_tasks:
    - debug:
        var: ansible_limit
        verbosity: 1

    - name: Limit the playbook run to explicitly named instances.
      assert:
        that:
          - ansible_limit is defined
          - ansible_limit | trim | length > 4
          - ansible_limit | wordcount > 0
        fail_msg: "Instance names are required in the job limit to keep from accidentally changing all instance types in AWS."
        success_msg: "Limit identified."
      tags:
        - always

    - debug:
        var: resize_instance_to
        verbosity: 1

    - name: Input validation on expected variables.
      assert:
        that:
          - resize_instance_to is defined
          - resize_instance_to | trim | length > 3
          - resize_instance_to | wordcount > 0
        fail_msg: "A new instance type must be defined in resize_instance_to (e.g. t3a.large)."
        success_msg: "New instance type defined."
      tags:
        - always

  tasks:
  - name: Change instance type.
    block:
      - name: Stop EC2 instance.
        ec2:
          region: "{{ ec2_region }}"
          instance_ids:
            - "{{ ec2_id }}"
          state: stopped
          wait: yes
        delegate_to: 127.0.0.1
        when: ec2_state == "running"

      - name: Previous instance type.
        debug:
          var: ec2_instance_type

# ec2 module doesn't support resizing.
# https://github.com/ansible/ansible/issues/33373#issuecomment-456695343
      - name: "Resize EC2 instance."
        shell: >
          aws ec2 modify-instance-attribute --instance-id "{{ ec2_id }}"
          --instance-type "{{ resize_instance_to }}" --region "{{ ec2_region }}"
        delegate_to: 127.0.0.1
        register: resize_result
        tags:
        - skip_ansible_lint

      - debug:
          var: resize_result
          verbosity: 1

      - name: Start EC2 instance.
        ec2:
          region: "{{ ec2_region }}"
          instance_ids:
            - "{{ ec2_id }}"
          state: running
          wait: yes
        delegate_to: 127.0.0.1
        when: ec2_state == "running"

    rescue:
      - debug:
          msg: "Resize failed! Reverting to previous instance type."

      - name: Stop EC2 instance.
        ec2:
          region: "{{ ec2_region }}"
          instance_ids:
            - "{{ ec2_id }}"
          state: stopped
          wait: yes
        delegate_to: 127.0.0.1
        when: ec2_state == "running"

      - name: "Revert EC2 instance size."
        shell: >
          aws ec2 modify-instance-attribute --instance-id "{{ ec2_id }}"
          --instance-type "{{ ec2_instance_type }}" --region "{{ ec2_region }}"
        delegate_to: 127.0.0.1
        register: revert_result
        tags:
        - skip_ansible_lint

      - debug:
          var: revert_result
          verbosity: 1

      - name: Start EC2 instance.
        ec2:
          region: "{{ ec2_region }}"
          instance_ids:
            - "{{ ec2_id }}"
          state: running
          wait: no
        delegate_to: 127.0.0.1
        when: ec2_state == "running"