Lab 7 - Solution
""""""""""""""""

Mandatory
=========

Host Groups
-----------
* Edit your existing inventory file ``hosts``
* Create the host_group ``web`` and add your webservers
* Create the host_group ``db`` and add your dbserver
* Run the ping module to test the new host groups ``web`` and ``db``

.. code-block:: yaml

    # file: hosts
    [web]
    web1.pascal.lab
    web2.pascal.lab

    [db]
    db.pascal.lab

.. code-block:: bash

    # should only run on web1 and web2
    ansible -m ping web

    web1.pascal.lab | SUCCESS => {
        "changed": false,
        "ping": "pong"
    }
    web2.pascal.lab | SUCCESS => {
        "changed": false,
        "ping": "pong"
    }

    # should only run on db
    ansible -m ping db

    db.pascal.lab | SUCCESS => {
        "changed": false,
        "ping": "pong"
    }

group_vars
----------
* Create the ``group_vars`` directory in ``/home/ansible/training``
* Create ``group_vars/all.yml``
* add the variable ``myvar`` with the value ``variable for all servers``
* Run a task (ad-hoc or in playbook) on **all** servers to print out the variable ``myvar`` with the `Debug Module <http://docs.ansible.com/ansible/latest/modules/debug_module.html>`_

.. code-block:: bash

    mkdir /home/ansible/training/group_vars
    vi /home/ansible/training/group_vars/all.yml

.. code-block:: yaml

    # file: group_vars/all.yml
    ---
    myvar: variable for all servers

.. code-block:: bash

    ansible -m debug -a "msg='{{ myvar }}'" all
	
	# result
	web1.pascal.lab | SUCCESS => {
	    "msg": "variable for all servers"
	}
	web2.pascal.lab | SUCCESS => {
	    "msg": "variable for all servers"
	}
	db.pascal.lab | SUCCESS => {
	    "msg": "variable for all servers"
	}

* Add the variable ``myvar`` with the value ``variable for web servers`` only for the ``web`` group
* Run a task (ad-hoc or in playbook) on **all** servers to print out the variable ``myvar`` with the `Debug Module <http://docs.ansible.com/ansible/latest/modules/debug_module.html>`_

.. code-block:: yaml

    # file: group_vars/web.yml
    ---
    myvar: variable for web servers

.. code-block:: bash

    # web1 and web2 should have the new defined value
    ansible -m debug -a "msg='{{ myvar }}'" all

    web1.pascal.lab | SUCCESS => {
	    "msg": "variable for web servers"
    }
    db.pascal.lab | SUCCESS => {
        "msg": "variable for all servers"
    }
    web2.pascal.lab | SUCCESS => {
	    "msg": "variable for web servers"
    }

host_vars
---------
* Create the ``host_vars`` directory in ``/home/ansible/training``
* Create a host variable file for the server ``web1.<firstname>.lab``
* Add the variable ``myvar`` with the value ``host variable for web1``
* Run a task (ad-hoc or in playbook) on **all** servers to print out the variable ``myvar`` with the `Debug Module <http://docs.ansible.com/ansible/latest/modules/debug_module.html>`_

.. code-block:: bash

    mkdir /home/ansible/training/host_vars
    vi /home/ansible/training/host_vars/web1.<firstname>.lab

.. code-block:: yaml

    # file: host_vars/web1.pascal.lab
    ---
    myvar: host variable for web1

.. code-block:: bash

    # web1 should have the host_vars value
    ansible -m debug -a "msg='{{ myvar }}'" all

    web1.pascal.lab | SUCCESS => {
        "msg": "host variable for web1"
    }
    db.pascal.lab | SUCCESS => {
        "msg": "variable for all servers"
    }
    web2.pascal.lab | SUCCESS => {
        "msg": "variable for web servers"
    }

Role Variables & Loops
----------------------
* Extend your ``ntp`` role
* Create a ``vars/main.yml`` file
* Add list variable ``ntp_packages`` with the items ``ntp`` & ``ntpdate``
* Rewrite your ``tasks/main.yml``
* use the new defined variable ``ntp_packages`` in combination with ``with_items`` to install both packages (see Chapter Variables)
* Run the playbook

.. code-block:: yaml

    # file: roles/ntp/vars/main.yml
    ---
    ntp_packages:
      - ntp
      - ntpdate

    # file: roles/ntp/tasks/main.yml
    - name: install ntp packages
      apt:
        name: '{{ item }}'
        state: latest
      with_items:
        - '{{ ntp_packages }}'
      tags:
        - installation

    # run the playbook, ntpdate should be installed
    ansible-playbook ntp-role.yml


Role Default Variables
----------------------
* Extend your ``ntp`` role
* Create a ``defaults/main.yml`` file
* Add a list of servers to a new variable ``ntp_servers`` (you can use your example from your **lab4.yml**)

.. code-block:: yaml

    # file: roles/ntp/defaults/main.yml
    ---
    ntp_servers:
      - 0.ch.pool.ntp.org
      - 1.ch.pool.ntp.org
      - 2.ch.pool.ntp.org
      - 3.ch.pool.ntp.org

* Extend the ``tasks/main.yml`` with a debug task to print out the defined list variable ``ntp_servers``

.. code-block:: yaml

    # file: roles/ntp/tasks/main.yml
    - name: debug ntp_servers
      debug:
        msg: '{{ ntp_servers }}'


* Run the playbook and verify the debug output

.. code-block:: bash

    # run the playbook
    ansible-playbook ntp-role.yml

    TASK [ntp : debug ntp_servers] *************************************************
    ok: [web1.test.lab] => {
        "msg": [
            "0.ch.pool.ntp.org",
            "1.ch.pool.ntp.org",
            "2.ch.pool.ntp.org",
            "3.ch.pool.ntp.org"
        ]
    }


Commit your changes
-------------------
* add all files to your git repo and commit it

.. code-block:: bash

    git status
    git add roles/*
    git commit -m 'lab 7'