Working with ios_config module, use lines and parents parameters

The ios_config module – allows you to configure devices running IOS, as well as generate configuration templates or send commands based on a template.

Module parameters:

• after – what to do after commands
• before – what actions to perform before commands
• backup – a parameter that specifies whether to make a backup copy of the current configuration of the device before making changes. The file will be copied to the backup directory, relative to the directory in which the playbook is located
• config – parameter that allows you to specify the base configuration file against which changes will be compared. If it is specified, the module will not download the configuration from the device.
• defaults – parameter specifies whether to collect all information from the device, including default values. If you enable this option, the module will collect the current configuration using the sh run all command. By default, this option is disabled and the configuration is checked with the sh run command
• lines (commands) – list of commands to be configured. Commands must be specified without abbreviations and exactly in the form in which they will be in the configuration.
• match – parameter specifies how exactly commands should be compared
• parents – the name of the section where the commands should be applied. If the command is inside a nested section, the entire path must be specified. If this parameter is not specified, then the command is considered to be in global configuration mode
• replace – parameter specifies how to configure the device
• save – whether to save the current configuration to the start one. By default, the configuration is not saved.
• src – parameter specifies the path to the file containing the configuration or configuration template. Mutually exclusive with lines (that is, either lines or src can be specified). Replaces the ios_template module, which will be removed soon.

Use case lines (commands) in ios_config module of ansible

The easiest way to use the ios_config module is to send global configuration mode commands with the lines parameter.

For the lines parameter, there is an alias commands, that is, you can write commands instead of lines.

Example playbook ios_config_lines.yml:

---
- name: Run cfg commands on routers
  hosts: cisco-routers
  gather_facts: false
  
  tasks:
    - name: Config password encryption
      ios_config:
        lines:
          - service password-encryption

and file group_vars/all.yml with connection variables:

ansible_connection: network_cli
ansible_network_os: ios
ansible_user: cisco
ansible_password: cisco
ansible_become: yes
ansible_become_method: enable
ansible_become_pass: cisco1

Playbook execution result:

$ ansible-playbook 1_ios_config_lines.yml

Ansible executes these commands:

• terminal length 0
• enable
• show running-config – to check if this command exists on the device. If the command is present, the task will not be executed. If there is no command, the task will be executed
• if the command specified in the task is not in the configuration: – configure terminal – service password-encryption – end

Be sure to write the commands in full, not abbreviated. And note that, for some commands, IOS itself adds parameters. If the command is not written in the form in which it is actually visible in the configuration file, the module will not be idempotent. It will always assume that there is no command and make changes every time.

The lines parameter allows you to send several commands (playbook ios_config_mult_lines.yml):

---
- name: Run cfg commands on routers
  hosts: cisco-routers
  gather_facts: false
  
  tasks:

    - name: Send config commands
      ios_config:
        lines:
          - service password-encryption
          - no ip http server
          - no ip http secure-server
          - no ip domain lookup

Execution result:

$ ansible-playbook ios_config_mult_lines.yml

Use case parents (commands) in ios_config module of ansible

The parents parameter is used to specify in which submode to apply the commands.

For example, you need to use the following commands:

line vty 0 4
  login local
  transport input ssh

In this case, playbook ios_config_parents_basic.yml would look like this:

---
- name: Run cfg commands on routers
  hosts: cisco-routers
  gather_facts: false
  
  tasks:
    - name: Config line vty
      ios_config:
        parents:
          - line vty 0 4
        lines:
          - login local
          - transport input ssh

The launch will be similar to the previous playbooks:

$ ansible-playbook ios_config_parents_basic.yml

If the command is in multiple nested modes, the submodes are listed in the parents list.

For example, you need to run the following commands:

policy-map OUT_QOS
 class class-default
  shape average 100000000 1000000

Then playbook ios_config_parents_mult.yml will look like this:

---
- name: Run cfg commands on routers
  hosts: cisco-routers
  gather_facts: false
  
  tasks:

    - name: Config QoS policy
      ios_config:
        parents:
          - policy-map OUT_QOS
          - class class-default
        lines:
          - shape average 100000000 1000000