Ansible overview

 Ansible is an open sourace automation tool or platform that can be used for configuration management, automation related to sysadmin tasks, application deployment and even for IAC at some extent.

 Ansible uses stateless protocol i.e it does not need to maintain server information and current session

Ansible directory structure:

more specifically

Ansible Architecture	Agentless
To communicate with nodes Ansible uses	ssh protocol
Ansible playbook uses	YAML syntax

What is Roles?

Each role is designed to achieve some desired result, So if you want to group multiple task at one place and you want to make them reusable, role is a way to do that.

it is a collection of tasks, templates, files, modules, etc

what is playbook?

Playbooks are written in YAML file, basically it is a way to excute roles and command in scripted way to all the servers or server group that is defined in invenotry file

Idempotency:

it is very good feature that ansible supports, basically it will not changed anything if server is already in desired state

Ansible galaxy:

It is like community or hub you can say where you can find the contents related to ansible like to install and configure httpd, nginx, etc

Modules:

When ansible connects to nodes over ssh there is a program called modules that get pushed along with it, basically it helps ansible to install, deleted, modifiy, etc and get removed when everything is done

what is ansible Ad-Hoc command?

Ad-Hoc commands are way to execute some commands on servers without writting any playbooks

Some Important ansible Ad-Hoc commands

To check whether you are able to ping servers or not

ansible all -m ping

Whenever you want to implement some play conditionally, this setup modules can help you, it gives information about servers or server group.

ansible all -m setup

Some more commands following:

ansible all -m shell -a 'fdisk -l' -u ec2-user --become -K

ansible all -m shell -a 'df -h' --become

ansible all -a "uptime"

ansible all -m copy -a 'src=/home/ec2-user/nginx/nginx.yml dest=/home/remote-user/nginx/ owner=root mode=0644' -u root --become -K

ansible node1 -m fetch -a 'src=/etc/sudoers.d/nginx.yml dest=/home/ec2-user/nginx/ flat=yes'

ansible all -m apt -a 'name=httpd state=latest' --become

ansible all -m apt -a 'name=httpd state=absent purge=yes' --become

ansible all -m service -a 'name=httpd state=started enabled=yes' --become

ansible all -m service -a 'name=httpd state=stopped' --become

Creating new directory

ansible abc -m file -a "dest = /home/ec2-user/new mode = 777 owner = ec2-user group = ec2-user state = directory"

Deleting whole directory and files

ansible abc -m file -a "dest = /home/ec2-user/new state = absent"

Frequently used tasks in Ansible

---
#Install and configure httpd
- name: Install and configure httpd
  hosts: worker
  gather_facts: true
  remote_user: root
  role:
    - ../roles/install-and-configure-httpd
    - ../roles/restart-httpd-service

#update hostsfile
- name: update hosts file
  hosts: master
  gather_facts: true
  remote_user: root
  role:
    - ../roles/update-hosts-file



- name: Run shell script
  shell: |
    chmod -R 755 /home/ec2-user/shell-script
  register: user
  ignore_errors: true
- debug: var=user.stdout   

- name: Run shell script
  shell: |
    chmod -R 755 /home/ec2-user/shell-script
  register: user
  ignore_errors: true
- debug: var=user.stdout   

when: user.stdout|int == 1

- name: check if user exist
  set_fact:
    message: "{% if user.stdout|int == 1 %} 'ansible User was created OK' {% else %} 'ansible user was not created' {% endif %}"
- debug: var=message  

- name: download rpm file
  get_url:
    url: "{{ansible_rpm_url}}"
    force: yes
    dest: /tmp/ansible-2.7.2.noarch.rpm
    timeout: 60
  retries: 5
  delay: 10

- name: configure httpd
  template:
    src: httpd.conf.j2
    dest: /etc/httpd/httpd.conf
  become: true

- name: Make sure following items directory exists
  file: path={{item}} state=directory
  with_items:
    - /opt/httpd
    - /etc/httpd
    - /home/.httpd

- name: Create dir
  file: path={{item}} state=directory owner=ec2-user group=ec2-user mode=0755
  with_items:
    - /home/abc
    - /home/cde
   

- name: include roles
  include_tasks: ../../../../test-roles/roles/fix-bug.yaml

- name: include roles
  include_tasks: ../../../../test-roles/roles/fix-bug.yaml
  when: fix_bug

- name: replace regex value in scripts
  replace:
    path: /tmp/install-httpd.sh
    regexp: '@directory_path@'
    replace: "'{{document_directory}}'"

- name: create users
  user:
    name: pankaj
    shell: /bin/bash
    groups: dev,sysadmin
    append: yes

- name: relaod and restart httpd
  systemd:
    state: restarted
    name: httpd
    enabled: yes

root@DESKTOP-3J3M43J:~# cat component-name/roles/init-httpd/handlers/main.yaml
- name: restart httpd
  service:
    name: httpd
    enabled: yes
    daemon_reload: yes
    state: restarted

- pause
    minutes: 1

- debug
    msg: welcome
  run_once: true

- name: add line in file
  lineinfile:
    path: "/etc/httpd/conf/httpd.conf"
    inserafter: ^\[Documentroot\]$
    line: "Documentroot: /var/lib/httpd"
  notify: httpd restart

- name: pip install ansible
  command: "/usr/bin/pip install ansible"
  become_user: "{{some_user}}"

#!/usr/bin


How to use Jinja2 Template in Ansible Playbook

• jinja2 is python based templating language.
• we use it mostly when we want to keep some configuration files or any file dynamic.
• When configuration changes are mostly dynamic you don't know the value before running the playbook then we use this template.
• We just keep the variable of Ansible-playbook in this jinja template which can get replaced while running the playbook.
• We can use loops and conditional statement to transform the data according to our requirement..
• It comes with .j2 extension.
• It is very easy to use.

Tags:

{#  #}  When you want to comment something to describe the tasks.

{%  %}  In control statement such as if-else, for loops we use this Tag.

{{  }}  This tag will replace the variable name with the actual value.

[pankaj@host]$ ansible-playbook ansible-playbook-example.yaml

References:

https://ansible-tips-and-tricks.readthedocs.io/en/latest/ansible/commands/

Thank you for reading!!