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Ansible playbooks layout and examples

Once you have ansible installed and ssh connectivity between the control server and other hosts established you can set up following directly layout with playbooks and execute the examples listed here.

These playbook examples are also available from my Github repository - https://github.com/shahkamran/ansibleplaybooks.

~/.
---+ansible.cfg
---+dev
---+hosts
---+playbooks/
-------------+webserver.yml


-------------+database.yml
-------------+loadbalancer.yml


So where do you start?
You set up your hosts file similar to /etc/hosts but a local one with IP address translation to your systems.

#hosts
192.168.0.1     control
192.168.0.2     app01
192.168.0.3     app02
192.168.0.4     db01
192.168.0.5     lb01

Next you set up your environment in dev file by creating groups of hosts.

#dev
[cc]
control ansible_connection=local
[apps]
app01
app02
[dbs]
db01
[lbs]
lb01

This brings us to the playbooks that you can use as test to execute and build environment.

#loadbalancer.yml
---
  - hosts: lbs
    become: true
    tasks:
        - name: install nginx
          apt: name=nginx state=present update_cache=yes

        - name: ensure nginx started
          service: name=nginx state=started enabled=yes

You can run above using command below;
ansible-playbook loadbalancer.yml

Lets get the web servers set up as well on app servers.

#webserver.yml
---
  - hosts: apps
    become: true
    tasks:
        - name: install web server components
          apt: name={{item}} state=present update_cache=yes
          with_items:
                - apache2
                - libapache2-mod-wsgi
                - python-pip
                - python-virtualenv

        - name: ensure apache2 started
          service: name=apache2 state=started enabled=yes

        - name: ensure mod_wsgi enabled
          apache2_module: state=present name=wsgi
          notify: Restart Apache2
    handlers:
        - name: Restart Apache2
          service: name=apache2 state=restarted

Run following;
ansible-playbook webserver.yml

And the database goes here.

#database.yml
---
  - hosts: dbs
    become: true
    tasks:
        - name: install mysql-server
          apt: name=mysql-server state=present update_cache=yes

        - name: ensure mysql-server started
          service: name=mysql state=started enabled=yes

Get it up and running by;
ansible-playbook database.yml

That is all your environment set up now. If you want you can play with the examples above and enhance your usage, for example you can create a playbook to restart the whole application stack using below playbook.

#stack_restart.yml
---
# Bring stack down
- hosts: lbs
  become: true
  tasks:
  - service: name=nginx state=stopped

- hosts: apps
  become: true
  tasks:
  - service: name=apache2 state=stopped

# Restart mysql
- hosts: dbs
  become: true
  tasks:
  - service: name=mysql state=restarted

# Bring stack up
- hosts: apps
  become: true
  tasks:
  - service: name=apache2 state=started

- hosts: lbs
  become: true
  tasks:
  - service: name=nginx state=started

You restart your stack using command below;
ansible-playbook stack_restart.yml

Hope you find these useful.

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