Training Course for Ansible Automation Platform

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Exercise 4 - Network Configuration with Jinja Templates

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Table of Contents


Demonstration templating a network configuration and pushing it a device


Step 1

This step will cover creating Ansible variables for use in an Ansible Playbook. This exercise will use the following IP address schema for loopbacks addresses on rtr1 and rtr2:

Device Loopback100 IP

Variable information can be stored in host_vars and group_vars. For this exercise create a folder named group_vars:

[student1@ansible networking-workshop]$ mkdir ~/networking-workshop/group_vars

Now create a file in this directory name all.yml using your text editor of choice. Both vim and nano are installed on the control node.

[student1@ansible networking-workshop]$ nano group_vars/all.yml

The interface and IP address information above must be stored as variables so that the Ansible playbook can use it. Start by making a simple YAML dictionary that stores the table listed above. Use a top level variable (e.g. nodes) so that a lookup can be performed based on the inventory_hostname:

    Loopback100: ""
    Loopback100: ""

Copy the YAML dictionary we created above into the group_vars/all.yml file and save the file.

All devices are part of the group all by default. If we create a group named cisco only network devices belonging to that group would be able to access those variables.

Step 2

Create a new template file named template.j2:

[student1@ansible networking-workshop]$ nano template.j2

Copy the following into the template.j2 file:

{% for interface,ip in nodes[inventory_hostname].items() %}
interface {{interface}}
  ip address {{ip}}
{% endfor %}

Save the file.

Step 3

This step will explain and elaborate on each part of the newly created template.j2 file.

{% for interface,ip in nodes[inventory_hostname].items() %}

The inventory_hostname variable is considered a magic variable which is automatically provided.

interface {{interface}}
  ip address {{ip}}


{% endfor %}

Step 4

Create the Ansible Playbook config.yml:

[student1@ansible networking-workshop]$ nano config.yml

Copy the following Ansible Playbook to the config.yml file:

- name: configure network devices
  hosts: rtr1,rtr2
  gather_facts: false
    - name: configure device with config
        config: "{{ lookup('template', 'template.j2') }}"

Step 5

Execute the Ansible Playbook:

[student1@ansible networking-workshop]$ ansible-playbook config.yml

The output should look as follows.

[student1@ansible ~]$ ansible-playbook config.yml

PLAY [rtr1,rtr2] ********************************************************************************

TASK [configure device with config] ********************************************************************************
changed: [rtr1]
changed: [rtr2]

PLAY RECAP ********************************************************************************
rtr1                       : ok=1    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
rtr2                       : ok=1    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Step 6

Use the command show ip int br to verify the IP addresses have been confirmed on the network devices.

[student1@ansible networking-workshop]$ ssh rtr1

rtr1#show ip int br | include Loopback100
Loopback100     YES manual up                    up



The finished Ansible Playbook is provided here for an answer key: config.yml.

The provided Ansible Jinja2 template is provided here: template.j2.


You have completed lab exercise 4

Click here to return to the Ansible Network Automation Workshop