Ansible Tutorial - Working with Variable and Facts

Working with Ansible Variable and Facts

Objectives

• Working with facts and variables in ansible

Pre-requisite

• Three working VMs; server, tester1 and tester2 with key based authentication

Sequence 1. Setting up the Environment

1. Login as

   ansible

   user, create a project directory, base. Under this directory create an inventory file and add current host “

   server

   ” to the file.

[ansible@server ~]$ mkdir base [ansible@server ~]$ cd base [ansible@server base]$ vi inventory server tester1 tester2

2. Create and Configure ansible.cfg, under the base project to identify how to connect remote hosts.

[ansible@server base]$ vi ansible.cfg [defaults] remote_user = ansible          ; use ansible user host_key_checking = false inventory = inventory          ; Inventory file exists in the current directory log_path = base.log            ; base.log file will be created/used as log file [privilege_escalation] become = True                  ; Become someone else to perform tasks become_method = sudo           ; use sudo become_user = root             ; Become root user become_ask_pass = False        , Don't ask for password with sudo

Sequence 2. Working with Ansible Variables

1. Create a playbook hello-world.yml, under the base project to work with variables.

$ vi hello-world.yml - hosts: server vars: demo_var1: Welcome to The SkillPedia! tasks: - name: Variable Example in Ansible debug: msg: "{{ demo_var1 }}"

Here 

demo_var1

variable is substituted by the value 

Welcome to The SkillPedia!

when the playbook is run. It simply prints the message 

Welcome to The SkillPedia!

.

2. Create another playbook

   yml

   to holds 6 country names in a variable

   Countries

   . Each of these can be accessed using index 0 as the first element. The example playbook below retrieve the value 

   Singapore

   (Index 4).

$ vi

list_var.yml

- hosts: server vars: Countries: - India - Nepal - United States - China - Singapore - France tasks: - name: List variable in Ansible debug: msg: "{{ Countries [4] }}" The variable list can also be represented as:

vars: Countries: [India,Nepal,United States,China,Singapore,France]

3. To list all items of the list, use the 

   with_items

   module as given below.

- hosts: server vars: Countries: [India,Nepal,United States,China,Singapore,France] tasks: - name: Array variable in Ansible debug: msg: "{{ item }}" with_items: - "{{ Countries }}"

4. Dictionary variables are supported in the playbook. To define the dictionary variable, ident the key-value pair below dictionary variable name. In this example, 

   vlans

   is the dictionary variable while 

   id

    and 

   port

    are the key-value pairs.

hosts: server vars: http_port: 8080 default_gateway: vlans: id: 10 port: 20 tasks: name: Configure default gateway system_configs: default_gateway_ip: "{{ default_gateway  }}" name: Label port on vlan 10 vlan_config: vlan_id: "{{ vlans['id']  }}" port_id: 1/1/ {{ vlans['port']  }}

Sequence 3. Working with Ansible Facts

Ansible provides a list of

predefined variables

referred to as 

Ansible facts

 and gathered when a playbook is executed. Ansible

facts

can be referenced in Jinja2 templates and playbooks but cannot be altered or defined by the user.

1. Here is the list of facts would be returned when you run the

$ ansible server -m setup

2. Try the same command for tester1 and tester2 and compare the output.

$ ansible tester1 -m setup $ ansible tester2 -m setup

3. If you want to access the 

   n’th

   element of the list, use listvariable[n]. Create a playbook with following contents. If you are doing copy/paste, copy the content in a notepad file, remove the commented line (line starting with #) and them paste them in the vi editor.

--- - name: Ansible Variable Example Playbook hosts: server tasks:    # display the variable data type    - debug:        msg:          - " Data type of 'ansible_architecture'  is {{ ansible_architecture | type_debug }} "          - " Data type of 'ansible_apparmor' is {{ ansible_apparmor | type_debug }} "          - " Data type of 'ansible_all_ipv4_addresses' is {{ ansible_all_ipv4_addresses | type_debug }} "    # Simply printing the value of fact which is Ansible UnSafe Text type    - debug:        msg: "{{ ansible_architecture }}"    # Accessing an element of dictionary    - debug:        msg: "{{ansible_apparmor.status}}"    # Accessing the list    - debug:        msg: "{{ansible_all_ipv4_addresses}}"    # Accessing the Second Element of the list    - debug:        msg: "{{ansible_all_ipv4_addresses[1]}}"

4. Screenshot of the File.

4. The Execution Output

4. To execute the playbook on all VMs change the host parameter as follows

4. Output will be as given in the following screen shot.

4. Login to “

   server

   ” as root user and create a custom fact file called factthat retrieves date and time.

# mkdir -p /etc/ansible/facts.d # vi /etc/ansible/facts.d/date_time.fact

9. Add the following lines in it.

#!/bin/bash DATE=`date` echo "{\"date\" : \"${DATE}\"}"

10. Change the permissions to make it executable:

# chmod +x /etc/ansible/facts.d/date_time.fact

11. Create a playbook on Ansible control node called check_date.yml.

$ vi check_date.yml --- - hosts: server tasks: - name: Get custom facts debug: msg: The custom fact is {{ansible_local.date_time}}

  It should appear as given in following screenshot

12. Append the fact file to the ansible_local variable. The ansible_local stores all the custom facts. Now run the playbook and observe Ansible retrieving information saved on the fact file:

$ ansible-playbook check_date.yml