Bootstrap may fail if epel repo enabled with some priority

[TeddyAndrieux]

Component:

'salt'

What happened:

When running bootstrap with epel repo enable and has some yum priority https://wiki.centos.org/PackageManagement/Yum/Priorities set on it, salt from epel repository is installed (2015.x).

So bootstrap fail because some expected function not here (like fopen)

[CRITICAL] Rendering SLS 'base:metalk8s.salt.minion.local' failed: Jinja error: 'module' object has no attribute 'fopen'
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/salt/utils/templates.py", line 364, in render_jinja_tmpl
    output = template.render(**decoded_context)
  File "/usr/lib/python2.7/site-packages/jinja2/environment.py", line 969, in render
    return self.environment.handle_exception(exc_info, True)
  File "/usr/lib/python2.7/site-packages/jinja2/environment.py", line 742, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "<template>", line 2, in top-level template code
  File "/var/cache/salt/minion/extmods/modules/metalk8s.py", line 211, in get_archives
    info = archive_info_from_tree(archive)
  File "/var/cache/salt/minion/extmods/modules/metalk8s.py", line 158, in archive_info_from_tree
    with salt.utils.files.fopen(product_txt) as fd:
AttributeError: 'module' object has no attribute 'fopen'

; line 2

---
{%- from "metalk8s/map.jinja" import metalk8s with context %}
{%- set archives = salt.metalk8s.get_archives() %}    <======================

Configure salt minion for local mode:
  file.serialize:
    - name: /etc/salt/minion.d/99-metalk8s-local.conf
    - user: root
[...]
---
local:
    Data failed to compile:
----------
    Rendering SLS 'base:metalk8s.salt.minion.local' failed: Jinja error: 'module' object has no attribute 'fopen'
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/salt/utils/templates.py", line 364, in render_jinja_tmpl
    output = template.render(**decoded_context)
  File "/usr/lib/python2.7/site-packages/jinja2/environment.py", line 969, in render
    return self.environment.handle_exception(exc_info, True)
  File "/usr/lib/python2.7/site-packages/jinja2/environment.py", line 742, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "<template>", line 2, in top-level template code
  File "/var/cache/salt/minion/extmods/modules/metalk8s.py", line 211, in get_archives
    info = archive_info_from_tree(archive)
  File "/var/cache/salt/minion/extmods/modules/metalk8s.py", line 158, in archive_info_from_tree
    with salt.utils.files.fopen(product_txt) as fd:
AttributeError: 'module' object has no attribute 'fopen'

; line 2

---
{%- from "metalk8s/map.jinja" import metalk8s with context %}
{%- set archives = salt.metalk8s.get_archives() %}    <======================

Configure salt minion for local mode:
  file.serialize:
    - name: /etc/salt/minion.d/99-metalk8s-local.conf
    - user: root
[...]
---
<< END >>

This script will now exit

Workaround:

Disable epel repository (as this repository is not needed at all for MetalK8s) to perform bootstrap or just unset the priority on epel repository.

What was expected:

Working bootstrap and Salt minion from our repo installed either:

• If salt-minion already installed in another version (may be downgraded or upgraded in bootstrap script)
• If other salt-minion packages available in another repo (likely 2015.x in epel repo even if a priority is set on this epel repository)

Steps to reproduce

Install the yum priority plugin, enable epel repository and set priority on epel repository to something between 1 and 98 and then bootstrap

yum install epel-release
yum install yum-plugin-priorities
vim /etc/yum.repos.d/epel.repo # set `priority=10` for epel repo

Resolution proposal (optional):

Force the salt-minion version we install in bootstrap script