Ansible

ANSIBLE:

It is a Configuration Management Tool.
Configuration: Ram, Storage, OS, Software and IP address of device.
Management: Update, Delete, Add.
Ansible is simple open-source IT engine which automates application deployment.
Orchestration, Security and compliance.
Uses YAML Scripting language which works on KEY-VALUE PAIR
Ansible GUI is called as Ansible Tower. It was just Drag and Drop.
Used PYTHON for Back end.

HISTORY:

Michael Dehhan developed Ansible and the Ansible project began in Feb 2012.
Ansible was taken over by Red-hat.
Ansible is Available for RHEL, Debian, CentOS, Oracle Linux.
Can use this tool whether your servers are in On-prem or in the Cloud.
It turns your code into Infrastructure i.e. Your computing environment has some of the same attributes as your application.

WHY ANSIBLE?:

While managing the multiple servers its hard to keep their configuration identical. If you have multiple servers which needs to configure the same setup in all. while doing the one to one server their might be a chances to miss some configuration steps in some servers.

Thats why automation tools come into play! The automation tools like Ansible, Chef,

Puppet and SaltStack all are based on a same principle.

DESCRIBE THE DESIRED STATE OF THE SYSTEM

Ansible uses plain SSH. so nothing needs to install on client machines. but other automation tools

like Chef/Puppet needs to install agent on client machine when we need to perform a task.

Ansible’s is light weight, relative easy to use and speed of deployment compared to other tools. Ansible handle either via standard SSH commands, or the Paramiko module which provides a Python interface to SSH2.

ANSIBLE WORKFLOW:

CHEF WORKFLOW:

SETUP:

ANSIBLE SERVER:

sudo -i

sudo amazon-linux-extras install ansible2 -y

yum install git python python-pip python-level openssl -y

vi /etc/ansible/hosts

vi /etc/ansible/ansible.cfg

useradd ansible

passwd ansible

visudo

vim /etc/ssh/sshd_config

ALL NODES

useradd ansible

passwd ansible

visudo

vim /etc/ssh/sshd_config

ALL SERVERS

sudo systemctl restart sshd

sudo systemctl status sshd

su - ansible

ANSIBLE SERVER:

ssh-copy-id ansible@localhost

yes & password

exit

ssh-copy-id ansible@privateip

yes & password

exit

HOST PATTREN:

‘all’ patterns refer to all the machines in an inventory.

ansible all–list-hosts ansible <groupname[remo]> --list-hosts

ansible <groupname> [remo][0] --list-hosts

groupname [0] – picks first machine of group

groupname [1] – picks second machine of group

groupname [-1] – picks last machine of group

groupname [1:4] – picks 2,3,4,5 machines in group

groupname [2:5] – picks 3 to 6 machines in the group

ansible all -m ping -v

If we want to push the code from Ansible server to nodes it can be done in 3 ways.

Ad-hoc Commands (Simple Linux) Ad-hoc means temporary & it will over-ride commands.

Modules – A Single Command.

Playbooks – More than one module is called Playbook.

Both module and Playbook is in YAML.

ADHOC COMMANDS:

These commands can be run individually to perform Quick functions.

Not used for configuration management and deployment, bcz the cmds are one time usage.

The ansible ad-hoc cmds uses /usr/bin/ansible/ command line tool to automate single task.

Go to ansible server and switch to ansible server

ansible remo -a “ls” [remo: Group name, -a: argument, ls: command]

ansible remo [0] -a “touch file1”

ansible all -a “touch file2”

ansible remo -a “sudo yum install httpd -y”

ansible remo -ba “yum install httpd -y” (b: become you will become sudo user)

ansible remo -ba “yum remove httpd -y”

MODULES:

Ansible ships with number of modules (called library modules) that can be executed directly to remote hosts or playbooks.

Your library of modules can reside on any machine, and there are no servers, daemons or database required.

The default location for the inventory file is /etc/ansible/hosts

Go to ansible server and switch to ansible server

ansible remo -b -m yum -a “pkg=httpd state=present” (install: present)

ansible remo -b -m yum -a “pkg=httpd state=latest” (update: latest)

ansible remo -b -m yum -a “pkg=httpd state=absent” (uninstall: absent)

ansible remo -b -m service -a “name=httpd state=started” (started: start)

ansible remo -b -m user -a “name=raj” (to check go to that servers and sudo cat /etc/passwd).

ansible remo -b -m copy -a “src=filename dest=/tmp” (to check go to that server and give ls /tmp).

PLAYBOOKS:

Playbooks in ansible are written in YAML language.

It is human readable & serialization language commonly used for configuration files.

You can write codes consists of vars, tasks, handlers, files, templates and roles.

Each playbook is composed of one or more modules in a list.

Module is a collection of configuration files.

Playbooks are mainly divided into sections like

TARGET SECTION: Defines host against which playbooks task has to be executed.

VARIABLE SECTION: Defines variables.

TASK SECTION: List of all modules that we need to run in an order.

YAML:

For ansible, nearly every YAML file starts with a list

Each item in the list is a list ok key-value pairs commonly called Dictionary.

All YAML files have to begin with ”---” and end with “…”

A dictionary is required in a simple key: value form (note: space before value is must)

For example:

--- # Customer details

Customer:

Name: abc

Age : 26 y

Salary: 100,000

Exp : 4 year

Extension for playbook file is .yml

BASIC POINTS:

Go to ansible server and login as ansible and create one playbook

Vi target.yml

---# Target Playbook

hosts: remo -- > remo: Groupname

user: ansible -- > ansible: You are ansible user now

become: yes -- > become: become sudo user -- > yes

connection: ssh

gather_facts: yes -- > Gives private IP of the nodes -- > yes

now save that file and execute the playbook by giving the command: ansible-playbook target.yml

Now create one more playbook in ansible server with cmd Vi task.yml

NORMAL PLAYBOOK:

TO EXECUTE: ansible-playbook playbook.yml

DRY RUN: Check whether the playbook is formatted correctly or not.

ansible-playbook playbook.yml --check

VARIABLES:

Ansible also provides various ways of setting variables. They are used to store values that can be later used in the playbook.

Variable names in Ansible should start with a letter. The variable can have letter, numbers and underscore. Invalid variable declaration comes when we use dot (.), a hyphen (-), a number or variable separated by multiple words.

other way of passing arguments is by passing them to the command line while running using the –extra-vars parameter.

Passing a Varaible file - A Varaible can be defined in a variable file and can be passed to a playbook using the include

HANDLERS:

Handler is same as task but it will run when called by another task. (OR)

It will run if the task contains a notify directive and also indicates that it changed something.

LOOPS:

Ansible loop includes changing ownership on several files & directories with file module, creating multiple users with user modules and repeating a polling step until result reached.

CONDITIONS:

If we have different scenarios, then we apply conditions according to the scenarios.

WHEN STATEMENT

Sometimes we want to skip a particular command on a particular node.

VAULT:

In ansible we can keep sensitive data like our passwords and keys in encrypted format.

ENCRYPTION TECHNIQUE: AES256 Used by Facebook.

ansible-vault create vault.yml : creating a new encrypted playbook.

ansible-vault edit vault.yml : Edit the encrypted playbook.

ansible-vault rekey vault.yml : To edit the password.

ansible-vault encrypt vault.yml : To encrypt the existing playbook.

ansible-vault decrypt vault.yml : To decrypt the encrypted playbook.

ROLES:

We can use two techniques for resulting a set of tasks they are Includes and Roles.

Roles are good for organizing tasks & encapsulating data needed to accomplish the task.

ANSIBLE ROLES: Default, Files, Handlers, Meta, Templates, Tasks, Vars.

We can organize playbooks into directory structure called Roles.

Adding more functionality to the playbooks will make it difficult to maintain in a single file.

mkdir -p playbook/roles/webserver/tasks --- > To see o/p use tree command.

Cd playbook & touch master.yml & touch roles/webserver/tasks/main.yml

vi roles/webserver/tasks/main.yml

TAGS:

If you have a large playbook, it may be useful to run only specific parts of it instead of running the entire playbook. You can do this with Ansible tags. Using tags to execute or skip selected tasks

TO EXECUTE A SINGLE TASK: ansible-playbook abc.yml --tags tagname

TO EXECUTE A MULTIPLE TASK: ansible-playbook abc.yml --tags tagname1,tagname2

TO SKIP A TASK: ansible-playbook abc.yml --skip-tags “uninstall”

GALAXY:

Ansible Galaxy is a galaxy website where users can share roles and to a command-line tool for installing, creating, and managing roles.

Ansible Galaxy gives greater visibility to one of Ansible's most exciting features, such as application installation or reusable roles for server configuration. Lots of people share roles in the Ansible Galaxy.

Ansible roles consist of many playbooks, which is a way to group multiple tasks into one container to do the automation in a very effective manner with clean, directory structures.

ansible-galaxy init raham

ansible-galaxy search elasticsearch

ansible-galaxy search elasticsearch --author alikins

ansible-galaxy install alikns.elasticsearch

cd /home/ansible/.ansible/roles/

USER INFO:

Go to the ansible galaxy website and select a username

ansible-galaxy info bonddim.linux

ansible-galaxy collection install bonddim.linux

ADVANTAGES:

Very simple to set up and use.

No special coding skills are necessary to use Ansible's playbooks.

Ansible lets you model even highly complex IT workflows.

You can orchestrate the entire application environment no matter where it's deployed.

DIS ADVANTAGES:

Ansible does not have any notion of state like other automation tools such as Puppet

Ansible does not track dependencies and simply executes sequential tasks and stops when tasks

finish, fail, or any error comes.

Ansible has external dependencies to Python modules

Windows interaction requires some scheming

Jenkins setup Uing playbook:

Playbook to create a file/folder:

TO ENTER A DATA IN A FILE:

Playbook to change permissions to a file:

playbook to deploy a webapp:

PIP MODULE:

Ansible pip module is used when you need to manage python libraries on the remote servers.

There are two prerequisites if you need to use all the features in the pip module.

The pip package should already be installed on the remote server.

Virtualenv package should be installed on the remote server already if you need to manage the packages in the python virtual environment.

RAW MODULE:

RAW module is used when there is more need than Command module or if the command module does not support the operation. This module makes a SSH to the remote machine and run the command. For the Ansible to work we need to have Python available but for this module we don’t need a Python to be available