Add Conditionals to Ansible Role for Idempotent Tasks Runs

Question

I've been searching for quite some time and tried many variants and similar answers without success. Hopefully this is something simple I am missing.

Ansible 2.9.6

I am creating many playbooks that all share a large set of custom Roles for my clients. I want to keep all logic out of the playbooks, and place that logic in the roles themselves to allow maximum re-usability. Basically, I just want to add boilerplate playbooks for simple "Role" runs via tags, with some vars overrides here and there.

My problem is that I can't seem to make some roles idempotent by using conditions - the conditionals don't work. The error I get is:

fatal: [localhost]: FAILED! => {"msg": "The conditional check 'homebrew_base.rc != 0' failed.
The error was: error while evaluating conditional (homebrew_bash.rc != 0): 'homebrew_bash' is undefined

The error appears to be in '/Users/eric/code/client1/provisioning/roles/bash/tasks/main.yaml': line 12, column 3, but may
be elsewhere in the file depending on the exact syntax problem.

The offending line appears to be:


- name: Change shell (chsh) for macOS to homebrew managed version
  ^ here
"}

Below is the boilerplate code for my playbooks:

# ./playbook.yaml

---
- name: Provisioning
  hosts: localhost
  connection: local

  pre_tasks:
    - include_vars: "{{ item }}"
    with_fileglob:
      - "{{ playbook_dir }}/vars/global.yaml"
  tags: always

tasks:

  - name: Use homebrew bash binary
    include_role:
      name: bash
    tags: bash

The above is truncated quite a bit, but only thing missing are additional var files and a whole bunch of include_roles.

Below is my role file in the entirely though. They are largely untested because of the error I keep getting.

# ./roles/bash/tasks/main.yaml

---
- name: Check /etc/shells contains "/usr/local/bin/bash"
  command: grep -Fxq "/usr/local/bin/bash" /etc/shells
  register: homebrew_bash
  ignore_errors: True
  changed_when:
    - homebrew_bash.rc != 0

- name: Check that homebrew installed /usr/local/bin/bash
  stat:
    path: /usr/local/bin/bash
  register: homebrew_bash_binary

- name: Change shell (chsh) for macOS to homebrew managed versoin
  tags: bash, chsh
  shell: chsh -s /usr/local/bin/bash
  become: yes
  when:
    - homebrew_bash.rc != 0
    - homebrew_bash_binary.stat.exists = True

Ps: I do plan on abstracting those hardcoded paths into roles/bash/defaults/. But I need it working first before that.

Ps2: If there is a better way to use a contains filter (instead of the grep hack), I'm all ears.

I've tried:

making separate tasks/chsh.yaml, and using the include: command to call that task within the role. When I do this, I get an odd error telling me the variable is undefined - in the tasks/chsh.yaml - even though I am checking for the variable in tasks/main.yaml! That doesn't seem right.
using quotes in various places in the conditions
commenting out each condition: both give the same error, just differenet names.

Again, I am trying to keep this logic in the roles only - not in the playbook.

Thanks!

score 0 · Accepted Answer · answered Mar 14 '20 at 20:09

Figured it out. I was missing the "tags" on the conditionals!

# ./roles/bash/tasks/main.yaml

---
- name: Check /etc/shells contains "/usr/local/bin/bash"
  tags: bash, chsh
  command: grep -Fxq "/usr/local/bin/bash" /etc/shells
  register: homebrew_bash
  ignore_errors: True
  changed_when:
    - homebrew_bash.rc != 0

- name: Check that homebrew installed /usr/local/bin/bash
  tags: bash, chsh
  stat:
    path: /usr/local/bin/bash
  register: homebrew_bash_binary

- name: Change shell (chsh) for macOS to homebrew managed versoin
  tags: bash, chsh
  shell: chsh -s /usr/local/bin/bash
  become: yes
  when:
    - homebrew_bash.rc != 0
    - homebrew_bash_binary.stat.exists = True

Add Conditionals to Ansible Role for Idempotent Tasks Runs

1 Answers1