==========================
Configuration Management 
==========================

=> Installing required softwares in the machines

=> Copy required files from one machine to another machine

=> OS Patching/Updates


=> We can perform configuration management in 2 ways

		1) Manual Configuration Management

		2) Automated Configuration Management

============================================
Problems with Manual Configuration Mgmt
============================================

1) Time Taking process

2) Repeated Work

3) Human Mistakes


Note: To overcome these problem we are going to automate configuration management in the project.

=> To automate configuration management we have several tools

				1) puppet
				2) chef
				3) Ansible (Trending)


================
What is Ansible
================

-> It is an open source software developed by Michael DeHaan and its ownership is under RedHat.

=> Ansible was written in Python language.

-> Ansible is an automation tool that provides a way to define configuration as code.


=======================
What Ansible can do ?
=======================

1) Automate Configuration Management

2) App Deployments


=======================
Ansible Architecture
=======================

1) Control Node

2) Managed Nodes

3) Host Inventory File

4) Playbooks


=> The machine which contains ansible software is called as Controlling Node.

=> The machines which are managing by Controlling Node are called as Managed Nodes.

=> Host inventory file contains managed nodes information.

=> Playbook is a YML/YAML which contains set of taks.


===============
Ansible Setup
===============

URL : https://github.com/ashokitschool/DevOps-Documents/blob/main/11-Ansible-Setup.md

===========================
Ansible Ad-Hoc Commands
===========================

=> To run ad-hoc commands we will follow below syntax


Syntax :  

$ ansible [all/group-name/private-ip] -m <module> -a <args>

Ex:   $ ansible all -m ping

	  $ ansible webservers -m ping

	  $ ansible dbservers -m ping

=> We have several modules in ansible to perform configuration management
		
		1) ping

		2) shell

		3) yum / apt

		4) service

		5) copy


$ ansible all -m ping

$ ansible all -m shell -a date

$ ansible all -m yum -a "name=git"

$ ansible webservers -m yum -a "name=httpd"

===========
Assignment
===========

=> Ansible Modules and purpose

=> What is YML 


===================
Ansible Playbooks
===================

=> Playbook is a YAML file

=> Playbook contains one or more tasks

=> Using playbook we can define what tasks to performed and where to be performed.

=> We will give playbook as input for ansible control node to perform tasks in managed nodes.

Note: To write Ansible playbooks, we should learn YAML first.

================
YML or YAML
================

=> YML/YAML stands for Yet another markup language.

=> It is used to store the data in human & machine readable format.

=> YML/YAML files will have extension as .yml or .yaml

-> Official Website :  https://yaml.org/


============================
01 - Sample YML file data
============================

Note: indent spacing is very important

---
id: 101
name: Ashok
gender: Male
hobbies:
 - music
 - chess
 - cricket
... 

===========================
02 - Sample YML file data
===========================	 

---
person:
 id: 101
 name: Ashok
 address:
  city: hyd
  state: TG
  country: India
 hobbies:
  - cricket
  - chess
  - music
...  
=============================  

Write YML file to represent employee data with company and job details.

emp -> id, name, company and job

company -> name

job -> exp, type (permanent | contract)


---
emp:
 id: 101
 name: Ashok
 company:
  name: Microsoft
 job:
  exp: 11 Years
  type: permanent
...


#### Website To validate YML syntax : https://www.yamllint.com/

################### Use VS Code IDE to write YML Files ######################

==================
Writing Playbooks
==================

=> Playbook contains 3 sections

    1) Host Section

    2) Variable Section

    3) Task Section

=> Host Section Represents target machines to execute tasks.

=> Variables Section is used to declare variables required for playbook execution.

=> Task section is used to define what operations we want to perform using Ansible.

Note: In single playbook we can specify multiple tasks also.

=> To execute playbook we will use below syntax

	$ ansible-playbook <playbook-yml-file>


=================================
Playbook to ping managed nodes
=================================

---
- hosts: all
  tasks:
  - name: ping all managed nodes
    ping:
...

# It will check the syntax of a playbook
$ ansible-playbook <playbook-yml-file> --syntax-check

# It will display which hosts would be effected by a playbook before run
$ ansible-playbook <playbook-yml-file> --list-hosts

# Run the playbook Using below command
$ ansible-playbook <playbook-yml-file>

# It execute one-step-at-a-time, confirm each task before running with (N)o/(y)es/(c)ontinue
$ ansible-playbook <playbook-yml-file> --step

# Run the playbook in verbose mode
$ ansible-playbook <playbook-yml-file> -vvv

====================
---
- hosts: all
  tasks:
  - name: create a file
    file: 
     path: /home/ansible/ashokit.txt
     state: touch
...
========================
---
- hosts: all
  tasks: 
  - name: copy content to file
    copy: content="welcome to ashokit\n" dest="/home/ansible/ashokit.txt"
...
===========================

---
- hosts: webservers
  become: true #use it if you need sudo priviliges
  tasks:
  - name: install httpd package
    yum:
     name: httpd
     state: latest
  - name: copy index.html file
    copy:
     src: index.html
     dest: /var/www/html/index.html
  - name: start httpd service
    service: 
     name: httpd
     state: started
...

=================
Handlers & Tags
=================

-> In playbook all tasks will be executed by default in sequential order.

=> Using Handlers we can execute tasks based on other tasks status.

Note: If 2nd task status is changed then only execute 3rd task.

-> Handlers are used to notify the tasks to execute.

=> 'notify' keyword we will use to inform handler to execute.

-> Using Tag we can map task to a tag-name

-> Using tag name we can execute particular task and we can skip particular task available in our playbook.


# to display all tags available in playbook
$ ansible-playbook handlers_tags.yml --list-tags

# Execute a task whose tag name is install
$ ansible-playbook handlers_tags.yml --tags "install"

# Execute the tasks whose tags names are install and copy
$ ansible-playbook handlers_tags.yml --tags "install,copy"

# Execute all the tasks in playbook by skipping install task
$ ansible-playbook handlers_tags.yml --skip-tags "install,copy"

============
Variables
============

=> Variables are used to store the data in key-value format

  Ex: id=100
      name=ashok
      age=20
      gender=male

=> In Ansible, we can use variables in 4 ways  

    1) Runtime Variables

    2) Playbook variables

    3) Group Variables

    4) Host Variables


==================
Runtime Variables 
==================

=> We can pass variable value in runtime like below

---
- hosts: webservers
  become: true
  tasks:
  - name: install package
    yum:
     name: "{{package_name}}"
     state: latest
...

$ ansible-playbook <yml> --extra-vars package_name=httpd



===================
Playbook Variables 
===================

=> We can declare variable value with in the playbook


---
- hosts: webservers
  become: true
  vars:
   package_name: httpd
  tasks:
  - name: install package
    yum:
     name: "{{package_name}}"
     state: latest
...

=========================================================================

Requirement : Write ansible playbook to install below softwares

In webservers group : install java

In dbservers group : install mysql

---
- hosts: all
  become: true
  tasks:
  - name: install soft
    yum:
     name: "{{package_name}}"
     state: latest
...

=> To achieve above requirement we need to use group vars concept

============
Group Vars
============

=> group vars concept is used to specify variable value for group of managed nodes as per inventory file.

=> Managed nodes we are configuring host inventory file like below

[webservers]
webserver1 ansible_host=172.31.0.95
webserver2 ansible_host=172.31.0.96

[dbservers]
172.31.5.185
172.31.5.186


=> While executing above playbook for webservers group i want to pass one package name and for dbservers group i want to pass another package name.

Note: We need to create variables based on group name

    Ex : 

        webservers.yml
        dbservers.yml

Note: group_vars related yml files we should create in host inventory file location

    Host Inventory file location : /etc/ansible/hosts

    webservers variable file : /etc/ansible/group_vars/webservers.yml        

    dbservers variable file : /etc/ansible/group_vars/dbservers.yml

===============
Host Variables 
===============   

=> host variables are used to specify variable value at host level (or) machine level

=> host vars we will create in below location


    Location : /etc/ansible/host_vars

    webserver1.yml

       package_name: java

    webserver2.yml

        package_name: python


Note-1: host variables will take precendence over group variables

Note-2: Variables defined in playbook override both host_vars and group_vars.

===============
Ansible Vault
===============

=> It is used to secure our playbooks

=> Using Ansible vault concept, we can encrypt & decrypt our playbooks

  Encryption : Convert data from readable format to un-readable format

  DeCryption : Convert data from un-readable format to readable format


# Encrypt our playbook
ansible-vault encrypt <yml-file-name>

Note: To encrypt a playbook we need to set one vault password

# see encrypted playbook
cat <yml-file-name>

# see orignal content of playbook
ansible-vault view <yml-file-name>

# to edit encrypted playbook
ansible-vault edit <<yml-file-name>>

# how to run encrypted playbook
ansible-playbook <yml-file-name> --ask-vault-pass

# decrypt playbook
ansible-vault decrypt <yml-file-name>



===============
Ansible Roles
===============

=> If we add more functionalities in a playbook then it will become very lengthy and it will be difficult to manage and maintain that playbook.

=> Using Roles concept we can break down large playbooks into smaller chunks.

=> Roles will provide abstraction for ansible configuration in a modular and re-usable format.


=> Below playbook we will divide into small chunks using Role concept

---
- hosts: webservers
  become: true #use it if you need sudo priviliges
  tasks:
  - name: install httpd package
    yum:
     name: httpd
     state: latest
  - name: copy index.html file
    copy:
     src: index.html
     dest: /var/www/html/index.html
  - name: start httpd service
    service: 
     name: httpd
     state: started
...

# To create a role we can use below command

Syntax : $ ansible-galaxy init <role-name>

==========================
Working with Ansible Role
==========================

### Step-1: Connect with control node and switch to ansible user

$ sudo su ansible
$ cd ~

### Step-2 : Create a role using 'ansible-galaxy'

$ mkdir roles
$ cd roles
$ ansible-galaxy init apache
$ sudo yum install tree
$ tree apache


### Step-3 : Create tasks inside "tasks/main.yml" like below

---
# tasks file for apache
- name: install httpd
  yum:
    name: httpd
    state: latest
- name: copy index.html
  copy:
    src=index.html
    dest=/var/www/html/
  notify:
    - restart apache
...

### Step-4 : Copy required files into "files" directory

Note: keep index.html file in files directory

### Step-5 : configure handlers in "handler/main.yml"

---
# handlers file for apache
- name: restart apache
  service:
    name: httpd
    state: restarted
...

Note: With above 5 steps our "apache"  role is ready now we can execute that role like below

### Step-6 : Create main playbook to invoke role using role name

$ cd ~
$ vi invoke-roles.yml

---
- hosts: all
  become: true
  roles:
    - apache
...