EX407-Ansible-Automation

Red Hat Certified Specialist in Ansible Automation (EX407) Preparation Course

• Understanding Core Components of Ansible
  • Understanding Core Components of Ansible Part 1
  • Understanding Core Components of Ansible Part 2
  • A Brief Tour of the Ansible Configuration File
  • LAB Getting Started with Ansible

Understanding Core Components of Ansible

Understanding Core Components of Ansible Part 1

This series of lessons lays the foundation for the remainder of the course content. Through a combination of lecture and command line demonstration, Students will gain a broad overview of Ansible. This particular lesson, focuses on Ansible inventories.

• Overview
  • Invetories
  • Modules
  • Variables
  • Facts
  • Plays
  • Playbooks
  • Configuration files

Inventories

• Inventory files may simply consist of a list of hostnames but can be much more robust

• It is also possible to define groups of hosts, host or group level variables, and groups of groups withing the inventory

• There are a number of variables that may be used within the inventory to control how ansible connects to and interacts with target hosts

• Commands to call ansible with ping module:

  • ansible innaghiyev1c.mylabserver.com -m ping -k - call ping module on innaghiyev1c.mylabserver.com host. Where -m ping is ping module and -k is key for asking password
  • ansible all -m ping -k - call all defined hosts in your inventory list /etc/ansible/hosts/
  • ansible -i inv.ini httpd -m ping -k - where -i - inventory file place, httpd hosts group name inside of inv.ini file

Output:

innaghiyev1c.mylabserver.com | SUCCESS => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python"
    },
    "changed": false,
    "ping": "pong"
}

Understanding Core Components of Ansible Part 2

This series of lessons lays the foundation for the remainder of the course content. Through a combination of lecture and command line demonstration, Students will gain a broad overview of Ansible. This particular lesson covers the following topics at a very high level: modules, variables, facts, plays, playbooks, and configuration files.

• Modules

  • Modules are essentially tools for particular tasks
  • Modules can take (and usually do) take parameters
  • They return JSON
  • Can run from the command line or within a playbook
  • There are a significant number of modules for many kinds of work
  • Custom modules can be written

• Variables

  • Variable names should be letters, numbers and underscores
  • Variables should always start with a letter
  • Can be scoped by a group, host, or even ini a playbook
  • Typically used for configuration values and various parameters
  • Variables can also be used to store the return value of executed commands
  • Ansible variables may also be dictionaries
  • There are a number of predefined variables used by Ansible

• Facts

  • Facts provide certain information about given target host
  • Facts are discovered by Ansible automatically when it reaches out to a host
  • Fact gathering may be disabled
  • Facts may be cached between playbook executions, but this is not default behavior

innaghiyev1c.mylabserver.com | SUCCESS => {
    "ansible_facts": {
        "ansible_all_ipv4_addresses": [
            "172.31.37.72"
        ],
        "ansible_all_ipv6_addresses": [
            "2a05:d01c:2c7:d802:4db1:18cc:f13f:a1cf",
            "fe80::9e:19ff:fe1e:7376"
        ],
        "ansible_apparmor": {
            "status": "enabled"
        },
        "ansible_architecture": "x86_64",
        "ansible_bios_date": "10/16/2017",
        "ansible_bios_version": "1.0",

• Plays and playbooks

  • The goal of a play is to map a group of hosts to some well-defined roles
  • A play may use one or more modules to achieve a desired end state on a group of hosts
  • A playbook is a series of plays
  • A playbook may deploy new web servers, install a new application to existing application servers, and run SQL against some database servers to support the new application

• Configuration Files

  • Several possible locations (in order processed):
    • ANSIBLE_CONFIG (an environment variable)
    • ansible.cfg (in the current directory)
    • .ansible.cfg (in the home directory)
    • /etc/ansible/ansible.cfg (master configuration)
  • Configuration can also be set in environment variables
  • Some commonly used settings:
    • ansible_managed
    • forks
    • Inventory

A Brief Tour of the Ansible Configuration File

The Ansible master configuration file is reviewed on a live system in this demonstration. Key configuration values are discussed as well as how to modify those values.

• Let's see some default values of ansible.cfg file located by /etc/ansible/ansible.cfg directory

[defaults]

# some basic default values...

#inventory      = /etc/ansible/hosts
#library        = /usr/share/my_modules/
#module_utils   = /usr/share/my_module_utils/
#remote_tmp     = ~/.ansible/tmp
#local_tmp      = ~/.ansible/tmp
#plugin_filters_cfg = /etc/ansible/plugin_filters.yml
#forks          = 5
#poll_interval  = 15
#sudo_user      = root
#ask_sudo_pass = True
#ask_pass      = True
#transport      = smart
#remote_port    = 22
#module_lang    = C
#module_set_locale = False

• Another handy block is following

[privilege_escalation]
#become=True
#become_method=sudo
#become_user=root
#become_ask_pass=False

LAB Getting Started with Ansible

Install Ansible on the control node.

• To install Ansible on the control node, run ansible.

yum install ansible

• If package not found run

yum install https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm

Configure the ansible user on the control node for ssh shared key access to managed nodes. Do not use a passphrase for the key pair.

• To create a keypair for the ansible user on the control host, run the following:

  • sudo su - ansible
  • ssh-keygen (accept all defaults: press enter for each prompt)

• Copy the public key to both node1 and node2.

• As the ansible user on the control host:

  • ssh-copy-id node1 (accept the host key if prompted, authenticate as ansible user)
  • ssh-copy-id node2 (accept the host key if prompted, authenticate as ansible user)

Create a simple Ansible inventory on the control node in /home/ansible/inventory containing node1 and node2.

• On the control host:
  • sudo su - ansible (if not already ansible user)
  • touch /home/ansible/inventory
  • echo "node1" >> /home/ansible/inventory
  • echo "node2" >> /home/ansible/inventory

Configure sudo access for Ansible on node1 and node2 such that Ansible may use sudo for any command with no password prompt.

• Log in to node1 as cloud_user and edit the sudoers file to contain appropriate access for the ansible user:
  • ssh cloud_user@node1
  • sudo visudo
  • Add the following line to the file and save:

ansible    ALL=(ALL)       NOPASSWD: ALL

• Repeate these steps for node2.

Verify each managed node is able to be accessed by Ansible from the control node using the ping module. Redirect the output of a successful command to /home/ansible/output.

• To verify each node, run the following as the ansible user from the control host:
  • ansible -i /home/ansible/inventory node1 -m ping
  • ansible -i /home/ansible/inventory node2 -m ping
• To redirect output of a successful command to /home/ansible/output:
  • ansible -i /home/ansible/inventory node1 -m ping > /home/ansible/output