Zabbix services should restart if pkg changes

[xenadmin]

I started playing around with forced version updates, and noticed that even if the packages install successfully, the service doesn't notice it. This PR could fix that.

Example:
/srv/pillar/zabbix/init.sls

# Overrides map.jinja
zabbix:
  lookup:
    version_repo: 4.0
    agent:
      version: 1:4.0.13-1+stretch
    proxy:
      version: 1:4.0.13-1+stretch

[xenadmin]

@hatifnatt: @myii pinged me, if I'm available for lifting the formula to 5.0. That reminded me of this open PR and I wanted to ask you for your opinion? That would help me catch up with my fork, so I could come back for improving.

[myii]

@hatifnatt I've been discussing some stuff about the formula with @xenadmin and we realised that this PR was still outstanding. Would you mind having a look and merging if all is OK? It's a relatively small change, so should be easy enough to review.

[myii]

Whoops, both at the same time!

[hatifnatt]

It's a good change for sure, but module run used for restart of Zabbix agent for a reason see #77

I can suggest to use it to preform restart after package changes too, like this:

zabbix-agent:
  pkg.installed:
    - pkgs:
      {%- for name in zabbix.agent.pkgs %}
      - {{ name }}{% if zabbix.agent.version is defined and 'zabbix' in name %}: '{{ zabbix.agent.version }}'{% endif %}
      {%- endfor %}
{% if salt['grains.get']('os') != 'Windows' %}
    - require_in:
      - user: zabbix-formula_zabbix_user
      - group: zabbix-formula_zabbix_group
{% endif %}
    - watch_in:
      - module: zabbix-agent-restart
  service.running:
    - name: {{ zabbix.agent.service }}
    - enable: True
    - require:
      - pkg: zabbix-agent
      - file: zabbix-agent-logdir
{% if salt['grains.get']('os') != 'Windows' %}
      - file: zabbix-agent-piddir
{% endif %}

zabbix-agent-restart:
  module.wait:
    - name: service.restart
    - m_name: {{ zabbix.agent.service }}

Things to notice:

zabbix-agent:
  pkg.installed:
    ...
    - watch_in:
      - module: zabbix-agent-restart

instead of

zabbix-agent:
  service.running:
    ...
    - watch:
      - pkg: zabbix-agent