Pulp

pulp_installer has the following task: https://github.com/pulp/pulp_installer/blob/master/roles/pulp_redis/tasks/main.yml#L16

- name: Add redis repository
  apt_repository:
    repo: ppa:chris-lea/redis-server
  become: yes
  when: ansible_distribution == 'Ubuntu'

This contradicts our policy against adding 3rd-party repos (anything beyond EPEL or the distro's misc optional repos) to a system.

The ansible task was added as part of this redmine task: https://pulp.plan.io/issues/4312

Considering that our Travis env was using Ubuntu 14.04 at the time, this strongly implies that the ansible task was a workaround for Ubuntu 14.04. Ubuntu 14.04 had redis 2.x, whereas CentOS 7 / EPEL 7 has redis 3.x (which we use successfully), and Ubuntu 16.04 has redis 3.x.

We have 2 possible solutions:

1. Remove the task entirely.
2. Make it only perform its logic on Ubuntu 14.04.

Either way, we cannot safely remove the repo from existing systems with a "cleanup"/delete task of some kind. (Since presumably redis will stop functioning if it is downgraded, but has /var state on disk.)

Also, our CI does not target Ubuntu currently. Debian 10 buster is the only targetted distro in the Debian family.