Commands for Demo of Ansible

Ansible Class

###### Ansible Installation on EC2 machine

Launch 2 AWS Ubuntu Instances, allow all traffic

## Install Ansible on Master :
sudo apt-get update && sudo apt-get install -y software-properties-common
sudo apt-add-repository ppa:ansible/ansible -y
sudo apt-get update && sudo apt-get install -y ansible
sudo apt-get update && sudo apt-get install -y docker.io
sudo apt-get update && sudo apt-get install -y maven
sudo apt --fix-broken install -y

## Install Python on Slaves
sudo apt-get update && sudo apt-get install -y python

## SSH Access from Master to Slaves
ssh ubuntu@<IP of Slaves> won't work

## On Master
cd .ssh && ls -lrt
show known_hosts and authorized keys
ssh-keygen
ls -lrt 
id_rsa.pub 
copy this content to authorized keys of Slave 

## On Slave
cd .ssh
Add the key to authorized keys

## On Master
Try the 1st ssh ubuntu@<IP of Slaves> should work now

## Set up Ansible Host and Test Connection
/etc/ansible/hosts file
Add Ansible Slave details in the file 
[group name]
slave1 ansible_ssh_host=<IP of Slave>
Optional
[all:vars]
ansible_python_interpreter=/usr/bin/python3

$ansible -m ping all
$ansible -m ping slave1
$ansible -m ping [group name]

Install something on localhost using ansible
ansible localhost -m ansible.builtin.sudo -a "name=docker state=latest" -b



ubuntu@ip-172-31-19-63:/etc/ansible/roles$ tree apache2
apache2
├── README.md
├── defaults
│   └── main.yml
├── files
│   ├── apache2.conf
│   └── copy.html
├── handlers
│   └── main.yml
├── meta
│   └── main.yml
├── tasks
│   ├── configure.yml
│   ├── install.yml
│   ├── main.yml
│   └── service.yml
├── templates
├── tests
│   ├── inventory
│   └── test.yml
└── vars
    └── main.yml

8 directories, 13 files

ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/tasks$ ls -lrt
total 16
-rw-r--r-- 1 root root  82 Jun 26 11:46 install.yml
-rw-r--r-- 1 root root  79 Jun 26 11:47 service.yml
-rw-r--r-- 1 root root 243 Jun 26 11:58 configure.yml
-rw-r--r-- 1 root root 118 Jun 26 12:02 main.yml

ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/tasks$ cat main.yml
---
# tasks file for apache2
- include_tasks: install.yml
- include_tasks: configure.yml
- include_tasks: service.yml


ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/tasks$ cat install.yml
---
  - name: install apache2
    apt: name=apache2 update_cache=yes state=latest


ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/tasks$ cat configure.yml
---
#configure apache2.conf and send copy.html file
  - name: apache2.conf file
    copy: src=apache2.conf dest=/etc/apache2/
    notify:
     - restart apache2 service

  - name: send copy.html file
    copy: src=copy.html dest=/var/www/html/

ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/tasks$ cat service.yml
---
  - name: starting apache2 service
    service: name=apache2 state=started


ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/files$ ls -lrt
total 12
-rw-r--r-- 1 root root 7224 Jun 26 11:49 apache2.conf
-rw-r--r-- 1 root root   88 Jun 26 11:50 copy.html


ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/handlers$ ls -lrt
total 4
-rw-r--r-- 1 root root 108 Jun 26 11:52 main.yml
ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/handlers$ cat main.yml
---
# handlers file for apache2
  - name: restart apache2 service
    service: name=apache2 state=restarted



ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/meta$ ls -lrt
total 4
-rw-r--r-- 1 root root 1634 Jun 26 11:54 main.yml


ubuntu@ip-172-31-19-63:/etc/ansible$ cat site.yml
---
- hosts: prod_group
  become: true
  roles:
    - apache2


ansible-playbook site.yml --syntax-check

This playbook consists of two plays with following tasks:
Play 1: Execute a command in host1, Execute a script in host1
Play 2: Execute a script in host2, Install nginx in host2

sudo vi first_playbook.yml

• hosts: host1
  sudo: yes
  name: Play 1
  tasks:
  • name: Execute command ‘Date’
    command: date
  • name: Execute script on server
    script: test_script.sh
• hosts: host2
  name: Play 2
  sudo: yes
  tasks:
  • name: Execute script on server
    script: test_script.sh
  • name: Install nginx
    apt: name=nginx state=latest

Above will throw errors : sudo is deprecated, become=true
host1 and host2 are actually slave1 and slave2

---

• hosts: slave1
  become: true
  name: Play 1
  tasks:
  • name: Execute command ‘Date’
    command: date
  • name: Execute script on server
    script: test_script.sh
• hosts: slave2
  name: Play 2
  become: true
  tasks:
  • name: Execute script on server
    script: test_script.sh
  • name: Install nginx
    apt: name=nginx state=latest

Now create test_script1.sh in master

#!/bin/bash
echo Hello World from Apache > /var/www/html/1.html

Now create test_script2.sh in master

#!/bin/bash
echo Hello World from Nginx > /var/www/html/1.html

Rather for Demo, use this playbook

---

• hosts: slave1
  become: true
  name: Play 1
  tasks:
  • name: Install apache2
    apt: name=apache2 state=latest
  • name: Execute script on server
    script: test_script1.sh
• hosts: slave2
  name: Play 2
  become: true
  tasks:
  • name: Install nginx
    apt: name=nginx state=latest
  • name: Execute script on server
    script: test_script2.sh

Ansible Architecture

https://www.javatpoint.com/ansible-architecture#:~:text=Ansible%20is%20used%20to%20automate,the%20different%20hardware%20quite%20easily.

Push vs Pull based Configuration management systems

Push Based Configuration Management Tool
In this type of configuration management tool, the main server (where the configuration data is stored) pushes the configuration to the node (hence, the name). So, it is the main server that initiates communication, not the nodes. Which means that an agent/client may or may not be installed on each node.
Ansible is an example of a push based configuration management tool that doesn’t need an agent to be installed on the nodes. SaltStack is an example of a push based configuration management tool that needs an agent (minion) to be installed on the nodes. In both cases, its the main server that starts the communication and sends the configuration data to the nodes without the nodes asking for it.

Pull Based Configuration Management Tool
In this type of configuration management tool, the nodes pull the configuration information from the server (hence, the name).
A small software (called agent or client) is installed on every node. This agent/client will:
at regular intervals, get the configuration from the server
compare the configuration received from the server with the current configuration of the node
if there is any mis-match, take the steps required to match the configuration of the node with the configuration received from the server.
This means that, its always the agent/client that initiates communication, not the main server.
Chef & Puppet are good examples of such configuration management tools.

Ansible Roles

cd /etc/ansible/roles
sudo ansible-galaxy init apache2
cd apache2 && sudo tree apache2

Directory Structure

https://docs.ansible.com/ansible/latest/user_guide/playbooks_reuse_roles.html

ubuntu@ip-172-31-19-63:/etc/ansible/roles$ tree apache2
apache2
├── README.md
├── defaults
│   └── main.yml
├── files
│   ├── apache2.conf
│   └── copy.html
├── handlers
│   └── main.yml
├── meta
│   └── main.yml
├── tasks
│   ├── configure.yml
│   ├── install.yml
│   ├── main.yml
│   └── service.yml
├── templates
├── tests
│   ├── inventory
│   └── test.yml
└── vars
└── main.yml

8 directories, 13 files

ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/tasks$ ls -lrt
total 16
-rw-r--r-- 1 root root 82 Jun 26 11:46 install.yml
-rw-r--r-- 1 root root 79 Jun 26 11:47 service.yml
-rw-r--r-- 1 root root 243 Jun 26 11:58 configure.yml
-rw-r--r-- 1 root root 118 Jun 26 12:02 main.yml

ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/tasks$ cat main.yml

tasks file for apache2

• include_tasks: install.yml
• include_tasks: configure.yml
• include_tasks: service.yml

ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/tasks$ cat install.yml

• name: install apache2
  apt: name=apache2 update_cache=yes state=latest

ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/tasks$ cat configure.yml

#configure apache2.conf and send copy.html file

• name: apache2.conf file
  copy: src=apache2.conf dest=/etc/apache2/
  notify:

  • restart apache2 service

• name: send copy.html file
  copy: src=copy.html dest=/var/www/html/

ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/tasks$ cat service.yml

• name: starting apache2 service
  service: name=apache2 state=started

ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/files$ ls -lrt
total 12
-rw-r--r-- 1 root root 7224 Jun 26 11:49 apache2.conf
-rw-r--r-- 1 root root 88 Jun 26 11:50 copy.html

ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/handlers$ ls -lrt
total 4
-rw-r--r-- 1 root root 108 Jun 26 11:52 main.yml
ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/handlers$ cat main.yml

handlers file for apache2

• name: restart apache2 service
  service: name=apache2 state=restarted

ubuntu@ip-172-31-19-63:/etc/ansible/roles/apache2/meta$ ls -lrt
total 4
-rw-r--r-- 1 root root 1634 Jun 26 11:54 main.yml

ubuntu@ip-172-31-19-63:/etc/ansible$ cat site.yml

• hosts: prod_group
  become: true
  roles:
  • apache2

ansible-playbook site.yml --syntax-check