Struggling with optional arguments to a playbook

[Martin Brooks]

Hello

I have a simple playbook that distributes my SSH key.   I tried to make a more generic version of the playbook that would accept arguments via -e so that the same playbook could distribute either a different key or a key for a different user.  This is what I have so far:


---
- hosts: all
  vars:
    username: "{{ username if username is defined else {{ansible_user_id}} }}"
    ssh_public_key: "{{ lookup('file', '{{ keyfile }}') if keyfile is defined else lookup('file', '/home/{{ username }}/.ssh/id_rsa.pub') }}"


  tasks:

    - debug: var=ssh_public_key
    - debug: var=username

    - name: Make sure the user's ~/.ssh exists.
      file:
        path: /home/{{ username }}/.ssh
        state: directory
        owner: "{{ username }}"
        group: domain^users
        mode: 0750

    - name: Distribute my key
      become: true
      authorized_key:
        user: "{{ username }}"
        key:  "{{ ssh_public_key }}"
        manage_dir: yes


This fails when invoked with no arguments (i.e. nothing passed via -e) but I simply do not understand the error message:

TASK [debug] ******************************************************************************************************************************************************************************************************
fatal: [dgsdtstlum01.mcs.local]: FAILED! => {"failed": true, "msg": "{{ lookup('file', '{{ keyfile }}') if keyfile is defined else lookup('file', '/home/{{ username }}/.ssh/id_rsa.pub') }}: {{ username if username is defined else {{ansible_user_id}} }}: template error while templating string: expected token ':', got '}'. String: {{ username if username is defined else {{ansible_user_id}} }}"}

I apologise if this is a simple error, but I've been bashing at it for hours with no success and google isn't being forthcoming. Where exactly is it expecting a ":" and why?

This is ansible version 2.3.0.  Thanks for reading.

Regards

Martin.

[Brian Coca]

rule #1 of templating: moustaches do not stack!

you cannot have {{ }} inside {{ }}. rewrite as:

username: "{{ username if username is defined else ansible_user_id }}"

or

username: {{ username|default(ansible_user_id) }}

or

vars_prompt:
name: username
default: "{{ansible_user_id}}

^ vars prompt is automatically overridden by -e.
----------
Brian Coca

[Martin Brooks]

Thanks for that.   I eventually managed to get it working via this method:

---
- hosts: all

  tasks:
    - set_fact:
        username: "{{ username | default(ansible_user_id) }}"
    - set_fact:
        keyfile: "{{ keyfile | default('/home/' + username + '/.ssh/id_rsa.pub') }}"
    - set_fact:

        ssh_public_key: "{{ lookup('file', '{{ keyfile }}') }}"

Interestingly, or not, it fails if I attempt to collapse the three set_fact statements into one stanza:

TASK [set_fact] ***************************************************************************************************************************************************************************************************
fatal: [dgsdtstlum01.local]: FAILED! => {"failed": true, "msg": "the field 'args' has an invalid value, which appears to include a variable that is undefined. The error was: 'username' is undefined\n\nThe error appears to have been in '/home/mbrooks/ansible-config/books/distribute_ssh_key.yaml': line 5, column 7, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n  tasks:\n    - set_fact:\n      ^ here\n"}

Some kind of scope guarding?  Moustaches not stacking noted, thankyou.


Mart.

[Brian Coca]

you are still stacking:

ssh_public_key: "{{ lookup('file', '{{ keyfile }}') }}"

should be:

ssh_public_key: "{{ lookup('file', keyfile) }}"


----------
Brian Coca