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# Ansible Certification: Red Hat EX407
- Notes from O'Reilly Course by Sander van Vugt
- tasks :
- name: Ansible Fundamentals # Space after - is mandatory !
- name: Lession 1 Taking an Ansible Test-drive
- ansible.cfg
- inventory
- anisble modules location (in macOS) : /usr/local/lib/python3.7/site-packages/ansible/modules/
- ansible localhost -m ping
- ansible localhost -a "whoami"
- anisble all -a "id" # label all is implicit meaning all hosts in the inventory
- ansible localhost -m command -a "id"
- ansible localhost -m command -a "date"
- ansible localhost -m shell -a "date"
- privilege escalation : become become_user become_method become_ask_pass
- pradeep ALL=(ALL) NOPASSWD: ALL (for sudo permissions) # /etc/sudoers.d/pradeep
- ssh-keygen
- ssh-copy-id user@remotehost
- yum search epel
- yum install epel-release
- yum search ansible
# ansible-lint package for syntax check
- name: Lession 2 Understanding Ansible Architecture
notes:
- ansible-doc -l
- ansible-doc -s ping
- ansible-doc -s slack
- ansible-doc -s copy
- ansible-doc -s template
- ansible-doc -s command
- ansible-doc -s yum
- ansible-doc -s file
- ansible-doc -s junos_facts
- name: Lession 3 Working with Playbooks
- ansible-playbook --syntax-check pb_collect_facts.yml
- ansible-playbook pb_collect_facts.yml --list-hosts
- ansible-playbook -C pb_collect_facts.yml # for Dry-Run
- ansible-playbook --step pb_collect_facts.yml
- lineinfile module # to modify an existing line in a file
- firewalld module
- name: Lession 4 Working wiht Variables,Inclusions and Task Control, Facts
- Highest level scope wins Global, Play, Host
- Global: command line or ansible.cfg file
- Host: individula hosts or groups via inventory file
- Playbook:
- hosts: all
vars: # keyword to define variables
user: pradeep
home: /home/pradeep
- Variable files:
- hosts: all
vars_files: # keyword to specify exterbal variable files
- vars/users.yml
# cat var/users.yml
# user: pradeep
# home: /home/pradeep
# user: suma
# home: /home/suma
- Using variables
- tasks:
- name : Creates the user
user:
name: "" # if the variable is used as the first element , double quotes mandatory !
- Importance of Project Directory wiht various files
- Host variables and Group variables
# These may be defined in the inventory file, but that is deprecated
# Recommended method to use group_vars and host_vars directories ...
# [webservers]
# server1.example.com
# [webservers:vars] ## To define variables inside inventory file
# user=pradeep
# Within the Project Directory , which contains the inventoru file create directories group_vars and host_vars
# If we have a host group "webservers" defined in the inventory,
# create file with the same name "group_vars/webservers" and in this file, define the variable
# Similarly for individul hosts, create a file wiht the name of the host and put it in "host_vars"
# for example, "host_vars/server1"
# Variables can be overwritten from command line with -e "key=value" option to the ansible-playbook command
# (base) pradeep-mbp:Desktop pradeep$ tree vardemo/ #Project Directory
# vardemo/
# |-- group_vars
# | |-- ftpservers
# | `-- webservers
# `-- inventory
# 1 directory, 3 files
# (base) pradeep-mbp:Desktop pradeep$ cat vardemo/inventory
# [webservers]
# server1.exmaple.com
# server2.example.com
# [ftpservers]
# server3.example.com
# server4.example.com
# A variable named "package" is defined which could be used in the respective playbooks as
# (base) pradeep-mbp:Desktop pradeep$ cat vardemo/group_vars/ftpservers
# package: vsftp
# (base) pradeep-mbp:Desktop pradeep$ cat vardemo/group_vars/webservers
# package: http
# (base) pradeep-mbp:Desktop pradeep$
# Arrays : Variables that define multiple values
- example array
users:
pradeep:
first_name: pradeep
last_name: gadde
home_dir: /home/pradeep
suma:
first_name: suma
last_name: gadde
home_dir: /home/suma
# we may refer to these using the following syntax - users.pradeep.first_name , users.suma.home_dir etc ..
- Using Facts # discovered information about a host, can be used as conditions to run specific tasks only when necessary
# The "setup" module is used to gather facts
- ansible server1.example.com -m setup
# We can filter facts with -a 'filter=..' Level 1 info
- ansible server1.example.com -m setup -a 'filter=ansible_kernel'
- ansible localhost -m setup -a 'filter=ansible_kernel'
# [WARNING]: No inventory was parsed, only implicit localhost is available
# localhost | SUCCESS => {
# "ansible_facts": {
# "ansible_kernel": "19.4.0"
# },
# "changed": false
# }
- Custom Facts : manually created by Admins
# INI or JSON format wiht .fact extension stored in /etc/ansible/facts.d
# will be shown as "ansible_local"
# Inclusions both for tasks and variables
- include_vars
- include
# Variable Precedence include_vars > Global Scope (command line -e option or ansible.cfg) > Playbook > Host Level
tasks:
- name: Read the tasks.yml to find what to do
include: tasks.yml # Main task definition included here
vars: # vaiables will be defined in the main file
package: samba
service: smb
state: started
register: output
# cat tasks.yml
# - name: install the
# yum:
# name: ""
# state: latest
# - name: start the
# service:
# name: ""
# state: ""
# Include_vars Example
- name: Install some packages
hosts: all
tasks:
- name: include packages
include_vars: packages.yml ## variables are defined here in this file
- name: installs
yum:
name:""
state: latest
# cat packages.yml
# ---
# packages:
# my_pkg: httpd
- name: Lession 5 Using Flow Control, Conditionals, Jinja Templates
# A loop is used to process a series of values in an array
# simple loop "with_items" statement
- yum:
name: "" # the item variable follows from the with_items loop type
state: latest
with_items:
- nmap
- net-tools
# - name: create users
# hosts: all
# tasks:
# - user:
# name: ""
# state: present
# groups: "
# with_items:
# - { name: 'pradeep',groups: 'wheel'}
# - { name: 'suma',groups: 'root'}
# Nested Loops - a loop inside a loop
# Ansible iterates over the first array and applies the values in the second array to each item in the first array
# with_nested is the keyword for this type of loop
- name: give users access to multiple databases
mysql_user:
name: ""
priv: ".*:ALL"
append_privs: yes
password: 'foo'
with_nested:
- [ 'pradeep','suma']
- [ 'clientdb','employeedb','providerdb']
# Other loop types are with_file, with_fileglob,with_sequence, with_random_choice ..
# Working with Conditionals
# To run tasks only on hosts that meet specific conditions
# == < > <= != isdefined is not defined etc
# When statement is used to implement a condition
# when statement must be indented outside a module, at the top level of the task
- name: Install the mariadb package
package:
name: mariadb
when: inventory_hostname in groups["databases"]
# multiple conditions can be combined with and or
# we can use "register" to save the information about the result of a task into a variable
# result.rc could be used in when conditions
# Jinja2 templates
# cat motd.j2
# This is the system .
# Today it is .
# Only use this system if has granted you permission !
# cat motd.yml
# - hosts: all
user: user
become: true
vars:
system_owner: pradeep@example.com
tasks:
- template:
src: motd.j2
dest: /etc/motd
owner: root
group: root
mode: 0644
