Define and implement specs for bootstrap-os (#4455)

* Add README to bootstrap-os role

* Rework bootstrap-os once more

* Document workarounds for bugs/deficiencies in Ansible modules
* Unify and document role variables
* Remove installation of additional packages and repositories
* Merge Ubuntu and Debian tasks
* Remove pipelining setting from default playbooks
* Fix OpenSUSE not running its required tasks

roles/bootstrap-os/tasks/bootstrap-centos.yml

@@ -1,10 +1,13 @@
 ---
-- name: Check if atomic host
+# CentOS ships with python installed
+
+- name: Check if this is an atomic host
   stat:
     path: /run/ostree-booted
   register: ostree
 
-- set_fact:
+- name: Store the fact if this is an atomic host
+  set_fact:
     is_atomic: "{{ ostree.stat.exists }}"
 
 - name: Check presence of fastestmirror.conf
@@ -12,79 +15,34 @@
     path: /etc/yum/pluginconf.d/fastestmirror.conf
   register: fastestmirror
 
-# fastestmirror plugin actually slows down Ansible deployments
-- name: Disable fastestmirror plugin
+# the fastestmirror plugin can actually slow down Ansible deployments
+- name: Disable fastestmirror plugin if requested
   lineinfile:
     dest: /etc/yum/pluginconf.d/fastestmirror.conf
     regexp: "^enabled=.*"
     line: "enabled=0"
     state: present
   become: true
-  when: fastestmirror.stat.exists
+  when:
+    - fastestmirror.stat.exists
+    - not centos_fastestmirror_enabled
 
 - name: Add proxy to /etc/yum.conf if http_proxy is defined
   lineinfile:
     path: "/etc/yum.conf"
     line: "proxy={{ http_proxy }}"
-    create: yes
+    create: true
     state: present
   become: true
-  when: http_proxy is defined
+  when:
+    - http_proxy is defined
 
-- name: Install libselinux-python and yum-utils for bootstrap
-  yum:
-    name:
-      - libselinux-python
-      - yum-utils
+# libselinux-python is required on SELinux enabled hosts
+# See https://docs.ansible.com/ansible/latest/installation_guide/intro_installation.html#managed-node-requirements
+- name: Install libselinux-python
+  package:
+    name: libselinux-python
     state: present
   become: true
   when:
     - not is_atomic
-
-- name: Check python-pip package
-  yum:
-    list=python-pip
-  register: package_python_pip
-  when:
-    - not is_atomic
-
-- name: Install epel-release for bootstrap
-  yum:
-    name: epel-release
-    state: present
-  become: true
-  when:
-    - epel_enabled
-    - not is_atomic
-    - package_python_pip.results | length != 0
-
-- name: check python-httplib2 package
-  yum:
-    list: "python-httplib2"
-  register: package_python_httplib2
-  when:
-    - not is_atomic
-
-- name: Configure extras repository if python-httplib2 not avaiable in current repos
-  yum_repository:
-    name: extras
-    description: "CentOS-7 - Extras"
-    state: present
-    baseurl: "{{ extras_rh_repo_base_url }}"
-    file: "extras"
-    gpgcheck: yes
-    gpgkey: "{{extras_rh_repo_gpgkey}}"
-    keepcache: "{{ extras_rh_rpm_keepcache | default('1') }}"
-    proxy: " {{ http_proxy | default('_none_') }}"
-  when:
-    - not is_atomic
-    - package_python_httplib2.results | length == 0
-
-- name: Install pip for bootstrap
-  yum:
-    name: python-pip
-    state: present
-  become: true
-  when:
-    - not is_atomic
-    - package_python_pip.results | length != 0