Instructions on target host preparation for Ubuntu are outdated

[Fridtjof Mund]

- [x] This doc is inaccurate in this way:
  - Step 4: the kernel version is always > 3.13.0-34-generic with 18.04 and later. If the requirement is still 3.13.0-34-generic, this step is unnecessary and can be removed.
  - Step 5: I'm relatively certain that some of these packages are already installed by default nowadays (sudo definitely is). It could be shortened based on what 18.04 and 20.04 ship in their default installation.
  - Step 6: A search for linux-image-extra in the Ubuntu repos (including UCA) does not yield any results. After a quick search, those packages seem to be called linux-modules-extra now.
  - Step 8: Is chrony still the preferred choice instead of something like systemd-timesyncd? As I understand, the intention here is not to run an NTP server, but just synchronize the system time, right? In any case, updating this to use systemctl won't hurt.
- [ ] This is a doc addition request.
- [ ] I have a fix to the document that I can paste below including example: input and output.

-----------------------------------
Release: on 2020-09-11 19:22:37
SHA: 232bb43eb7bbc50f49ca2351a0dedc838bbfe5d1
Source: https://opendev.org/openstack/openstack-ansible/src/deploy-guide/source/targethosts.rst
URL: https://docs.openstack.org/project-deploy-guide/openstack-ansible/ussuri/targethosts.html

[Fridtjof Mund (fridtjofmund)]

Another observation:

Step 7 is unnecessary, as it is automated in the openstack_hosts role: https://github.com/openstack/openstack-ansible-openstack_hosts/blob/stable/ussuri/tasks/configure_metal_hosts.yml

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/755345

[Dmitriy Rabotyagov (noonedeadpunk)]

Regarding chrony - eventually it's installed and configured with hardening role, so this step can be totally omited in the docs. If you don't want to use chrony, and use ntp or systemd-timesyncd, it's worth setting `security_rhel7_enable_chrony: false` in your user_variables.yml

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/755345
Committed: https://git.openstack.org/cgit/openstack/openstack-ansible/commit/?id=456a816f40c76f435cd0b9e28d26ae2f84961ede
Submitter: Zuul
Branch: master

commit 456a816f40c76f435cd0b9e28d26ae2f84961ede
Author: Dmitriy Rabotyagov <email address hidden>
Date: Wed Sep 30 19:41:47 2020 +0300

    [doc] Adjust deployment docs

    Change-Id: Ia31a1c04c4e70d7180eb894f907368d7034ca41d
    Closes-Bug: #1897343