Ansible - Working with block module - ansible

Question

I'm starting out with Ansible and AWS.
I've created a playbook that launch new instance and later should attach existing volume to the new instance:
- name: launch instance
ec2:
key_name: "{{ aws_vars.key_name }}"
group: "{{ aws_vars.security_group }}"
instance_type: "{{ aws_vars.instance_type }}"
image: "{{ aws_vars.image }}"
region: "{{ aws_vars.region }}"
wait: yes
count: 1
instance_tags: "{{ tags }}"
monitoring: yes
vpc_subnet_id: "{{ subnetid }}"
assign_public_ip: yes
register: destination
- name: Attach volumes
ec2_vol:
device_name: xvdf
instance: "{{ destination.instances[0].instance_id }}"
region: "{{ aws_vars.region }}"
tags: "{{ ec2_tags }}"
id: "{{ volume_id }}"
delete_on_termination: yes
with_items: "{{ destination }}"
So far, so good, everything works.
I would like to add a clean-up method, so in case there will be an error of any type in the later modules, I won't have any garbage instances.
I've understood that the idea here will be to use block module, however when I've tried working with block here, nothing really happens:
---
# EC2 Migrations.
- hosts: localhost,
connection: local
gather_facts: no
tasks:
- name: Vars
include_vars:
dir: files
name: aws_vars
- name: Create instance
block:
- debug:
msg: "Launcing EC2"
notify:
- launch_instance
- Cloudwatch
rescue:
- debug:
msg: "Rolling back"
notify: stop_instance
handlers:
- name: launch_instance
ec2:
key_name: "{{ aws_vars.key_name }}"
group: "{{ aws_vars.security_group }}"
instance_type: "{{ aws_vars.instance_type }}"
image: "{{ aws_vars.image }}"
region: "{{ region }}"
wait: yes
count: 1
monitoring: yes
assign_public_ip: yes
register: new_ec2
- debug: msg="{{ new_ec2.instances[0].id }}"
- name: stop_instance
ec2:
instance_type: "{{ aws_vars.instance_type }}"
instance_ids: "{{ new_ec2.instances[0].id }}"
state: stopped
- name: Cloudwatch
ec2_metric_alarm:
state: present
region: "{{ aws_vars.region }}"
name: "{{ new_ec2.id }}-High-CPU"
metric: "CPUUtilization"
namespace: "AWS/EC2"
statistic: Average
comparison: ">="
threshold: "90.0"
period: 300
evaluation_periods: 3
unit: "Percent"
description: "Instance CPU is above 90%"
dimensions: "{'InstanceId': '{{ new_ec2.instances[0].id }}' }"
alarm_actions: "{{ aws_vars.sns_arn }}"
ok_actions: "{{ aws_vars.sns_arn }}"
with_items: "{{ new_ec2 }}"

Answer 1

You put debug task into the block. The debug module returns ok status, so:
it does not call a handler (this required changed status),
1.the rescue-section is never triggered (this requires failed status).
Thus it is expected that "nothing really happens".
You need to put your actual tasks into the block (I leave them intact, assuming they are correct):
- name: Create instance
block:
- name: launch_instance
ec2:
key_name: "{{ aws_vars.key_name }}"
group: "{{ aws_vars.security_group }}"
instance_type: "{{ aws_vars.instance_type }}"
image: "{{ aws_vars.image }}"
region: "{{ region }}"
wait: yes
count: 1
monitoring: yes
assign_public_ip: yes
register: new_ec2
- debug:
msg: "{{ new_ec2.instances[0].id }}"
- name: Cloudwatch
ec2_metric_alarm:
state: present
region: "{{ aws_vars.region }}"
name: "{{ new_ec2.id }}-High-CPU"
metric: "CPUUtilization"
namespace: "AWS/EC2"
statistic: Average
comparison: ">="
threshold: "90.0"
period: 300
evaluation_periods: 3
unit: "Percent"
description: "Instance CPU is above 90%"
dimensions: "{'InstanceId': '{{ new_ec2.instances[0].id }}' }"
alarm_actions: "{{ aws_vars.sns_arn }}"
ok_actions: "{{ aws_vars.sns_arn }}"
with_items: "{{ new_ec2 }}"
rescue:
- name: stop_instance
ec2:
instance_type: "{{ aws_vars.instance_type }}"
instance_ids: "{{ new_ec2.instances[0].id }}"
state: stopped