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

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

[db]
db.pascal.lab

# 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

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

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

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

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

# 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

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

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

# 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

# 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)

# 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

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

Run the playbook and verify the debug output

# 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

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