Red Hat Ansible for Network Automation

After completing this section, you should be able to use Ansible to apply configuration directives that have been generated from a Jinja2 template to a network device.

As a general rule, an *os_config module is the best choice for applying changes to devices. But there are exceptions; sometimes a special purpose module exists.

The ios_banner module gracefully handles multiline banners.

---
- name: play for setting banner motd on ios devices
  hosts: leaf1
  gather_facts: False

  tasks:
    - name: set banner motd
      ios_banner:
        banner: motd
        test: |
            Unuauthorized access to this device is prohibited
        state: present

Configuration statements can be embedded directly within playbooks:

---
- hosts: ios
  tasks:
    - ios_config:
        lines: hostname "{{ inventory_hostname }}"

Configuration statements can also be sourced from a local file:

---
- name: A playbook that uses a static file to configure Cisco network devices
  hosts: ios

  tasks:
    - set_fact:
        config_filepath: "{{ playbook_dir }}/configs"

    - name: configure using static config file
        ios_config:
        src "{{ config_filepath }}/{{ inventory_hostname }}.cfg

Jinja2 templates can be used to generate the files sourced to configure devices.

---
- name: A play that uses a Jinja2 template to generate a set of config files
  hosts: ios
  connection: local

  tasks:
  - template:
      src: ios-leaf-common.j2
      dest: "{{ config_filepath }}/{{ inventory_hostname }}.cfg"

- name: A play that applies configs generated above to network devices
  hosts: ios

  tasks:
  - name: configure using static config file
    ios_config:
      src: "{{ config_filepath}}/{{ inventory_hostname }}.cfg

  - name: save running to startup when modified
    ios_config:
      save_when: modified

Ansible *os_config modules are designed to support Jinja2 templates directly, so you can generate configurations and apply them in with a single task.

---
- name: A play that generates configs and applies them in one step
  hosts: ios

  tasks:
  - name: configure using static config file
    ios_config:
        src: ios-leaf.j2

  - name: save running to startup when modified
    ios_config:
      save_when: modified