Ansible systemctl --user for another user

Question

I'm logging into another computer as the unprivileged user ansible and I'd like to have ansible enable a systemd user service for the user bob.

Without ansible, the solution would be ssh bob@machine followed by systemctl --user enable service

However, with ansible, there are two problems:

1. Newer versions of ansible will refuse to become the unprivileged user bob if already logged in as another unprivileged user (ansible).
2. Even if this worked, dbus would not be started and systemctl would not be able to talk to systemd (if I understood this correctly).

A horribly ugly workaround would be to execute the shell command, have the remote host ssh into itself as bob and run the systemctl raw command there.

Is there a nicer way to get this done?

Answer 1

Both options are feasible.

1. remote_user: bob

- hosts: test_01
  become: no
  remote_user: admin

  tasks:

    - command: whoami
      register: result
    - debug:
        var: result.stdout

    - command: whoami
      remote_user: bob
      register: result
    - debug:
        var: result.stdout

gives (abridged)

  result.stdout: admin
  result.stdout: bob

2. pipelining = true quoting from Becoming an Unprivileged User

Use pipelining. When pipelining is enabled, Ansible doesn’t save the module to a temporary file on the client. Instead, it pipes the module to the remote python interpreter’s stdin. Pipelining does not work for python modules involving file transfer (for example: copy, fetch, template), or for non-python modules.

- hosts: test_01
  become: no
  remote_user: admin

  tasks:

    - command: whoami
      register: result
    - debug:
        var: result.stdout

    - command: whoami
      become_user: bob
      become_method: sudo
      become: yes
      register: result
    - debug:
        var: result.stdout

gives (abridged) the same result

  result.stdout: admin
  result.stdout: bob

with

shell> grep pipe ansible.cfg 
pipelining = true