Anisible Rolling udpates using include_tasks

This repo is a playbook for installing webserver using rolling updates and include_tasks.

1. Rolling updates Deifintion - Why do I need a rolling udpate Scenario: Lets say You are updating a cluster of webservers. The way ansible executes is that it runs each task on all the managed hosts, at the same time. Therefore it affects all the hosts which might cause a downtime. However we can avoid this issue if we update the servers in groups of 2 or 3 or whatever is convenient. This can be achieved using Rolling Updates

---
- name: rolling updates
  hosts: all
  serial: 2
  tasks:
    - name:
      yum: 
      .....

2. Include_tasks

Include tasks is a way to distribute each task in seperate playbook files. One important aspect of include_tasks is that it is very memory friendly. The main playbook calls the children playbooks one by one therefore all playbooks are not loaded at the same time. It dynamically allocates the memory on the control nodes as and when they are called (as opposed to import_tasks)

Main file

include_web.yml is the main playbook to call other playbooks