How to conditionally execute group of tasks on ansible? - ansible

Question

I want to conditionally execute a set of tasks. Is there any syntax available that would let me execute a group of tasks, where the condition is evaluated once per whole group (like in a if statement in programming languages)?
Take a look at the code snippets below. I know the difference is small, but the first code better expresses my intention without polluting the namespace with additional variables (user_home_result2).
Pseudocode of what I want to do:
- name: Capturing user's home directory
shell: "getent passwd {{ user }} | awk -F: '{ print $6 }'"
register: user_home_result
- set_fact: user_home={{ user_home_result.stdout }}
- when: user_home != ''
- name: Setting up user {{ user }}
user: >
generate_ssh_key=yes
name="{{ user }}"
- name: Capturing user's home directory
shell: "getent passwd {{ user }} | awk -F: '{ print $6 }'"
register: user_home_result
- set_fact: user_home={{ user_home_result.stdout }}
Walkaround:
- name: Capturing user's home directory
shell: "getent passwd {{ user }} | awk -F: '{ print $6 }'"
register: user_home_result
- set_fact: user_home={{ user_home_result.stdout }}
- name: Setting up user {{ user }}
user: >
generate_ssh_key=yes
name="{{ user }}"
when: user_home != ''
- name: Capturing user's home directory
shell: "getent passwd {{ user }} | awk -F: '{ print $6 }'"
register: user_home_result2
when: user_home != ''
- set_fact: user_home={{ user_home_result2.stdout }}
when: user_home != ''

Answer 1

You can put the tasks in a new yml file and use a conditional include:
# subtasks.yml
---
- name: Setting up user {{ user }}
user: >
generate_ssh_key=yes
name="{{ user }}"
- name: Capturing user's home directory
shell: "getent passwd {{ user }} | awk -F: '{ print $6 }'"
register: user_home_result
- set_fact: user_home={{ user_home_result.stdout }}
And in the playbook:
- name: Capturing user's home directory
shell: "getent passwd {{ user }} | awk -F: '{ print $6 }'"
register: user_home_result
- set_fact: user_home={{ user_home_result.stdout }}
- include: subtask.yml
when: user_home != ''

Answer 2

As of version 2.1, ansible has blocks for logical task grouping. Blocks allow you to specify common things for a few tasks only once, including the when conditionals. Ex:
- block:
- name: put a file somewhere
copy: src=asdf dest=asdf
- name: put another file somewhere
template: src=asdf.j2 dest=asdf
when: bool_is_true
The above is equivalent to attaching a when: bool_is_true to both of the tasks inside the block.
More information at https://docs.ansible.com/ansible/latest/user_guide/playbooks_blocks.html