Deploying Device Configurations

Ansible playbooks used by netsim-tools deploy configurations through device-specific task lists and templates. When adding a new device type, you’ll have to create either a generic deploy configuration task list and a bunch of configuration templates, or a task list for every module supported by the device (plus the initial configuration).

You can also mix-and-match the two approaches. For example, you could have a generic deploy configuration task list, but use a separate list of tasks for initial configuration.

Search Paths

The Ansible playbooks try to find device-specific task lists or templates using netlab_device_type or ansible_network_os (when netlab_device_type is missing) Ansible variable. These variables are usually defined as device group variables in system settings.

The device type is set at the start of every Ansible playbook using set_fact module:

- tasks:
  - set_fact:
      netlab_device_type: "{{ netlab_device_type|default(ansible_network_os) }}"

Initial configuration deployment playbook looks for device/module specific Ansible task list in:

  • netsim/ansible/tasks/{{ netlab_device_type }}/{{ module }}.yml

  • netsim/ansible/tasks/deploy-config/{{ netlab_device_type }}.yml

The device configuration templates should be located in netsim/ansible/templates/{{ module }}/{{ netlab_device_type }}.j2

Finding Custom Configuration Templates

The following paths are searched when looking for custom configuration templates specified in config list or through a plugin:

  • Current directory (user plugins)

  • netsim/extra directory (system plugins)

When looking for a custom configuration template in the above search path, the following names are tried (custom_config is the name of custom configuration template or directory):

  • custom_config + '/' + netlab_device_type + '.j2' – device-specific templates within a subdirectory

  • custom_config + '.' + netlab_device_type + '.j2' – device-specific templates within the main directory

  • custom_config – verbatim custom configuration template name

  • custom_config + '.j2' – custom configuration template name specified without the .j2 filetype

The custom configuration could be deployed via a dedicated task list (netsim/extra/{{ custom_config }}/deploy.{{ netlab_device_type }}.yml) or via generic configuration deployment task list (see above)

Ansible Variables

The following Ansible variables are set before a device-specific task list is executed:

  • config_template – configuration template name (warning: the presence of configuration template might not be checked)

  • netsim_action – action currently being executed (initial, module name, or custom configuration name)

  • config_module – name of currently-deployed module (present only in the module configuration deployment phase of netlab initial)

  • custom_config – name of currently-deployed custom configuration (present only in the custom configuration deployment phase of netlab initial)

Sample Configuration Deployment Task Lists

Most network devices need a minimal configuration deployment task list, for example (Cisco IOS):

- cisco.ios.ios_config:
    src: "{{ config_template }}"

Some deployment task lists are a bit more complex. For example, Cumulus VX/FRR configuration deployment could use bash or vtysh:

- template:
    src: "{{ config_template }}"
    dest: /tmp/
- set_fact: deployed_config={{ lookup('template',config_template) }}
- command: bash /tmp/
  when: not ansible_check_mode and ("#!/bin/bash" in deployed_config)
- command: vtysh -f /tmp/
  when: not ansible_check_mode and not ("#!/bin/bash" in deployed_config)

Mikrotik RouterOS deployment copies a configuration file to the device with scp and executes an import command on the device:

- local_action:
    module: tempfile
    state: file
    suffix: temp
    prefix: ansible.{{ inventory_hostname }}.
  register: tempfile_1

- local_action:
    module: template
    src: "{{ config_template }}"
    dest: "{{ tempfile_1.path }}"

- local_action:
    module: command
    cmd: "scp -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -i {{ lookup('env', 'HOME') }}/.vagrant.d/insecure_private_key {{ tempfile_1.path }} vagrant@{{ ansible_host }}:config.rsc"

- routeros_command:
    commands: /import config.rsc

- local_action:
    module: file
    path: "{{ tempfile_1.path }}"
    state: absent
  when: tempfile_1.path is defined

You’ll find even more complex examples in deploy-config/srlinux.yml and deploy-config/sros.yml

Mixing Task Lists and Configuration Templates

Nexus OS configurations usually use configuration templates. deploy-config/nxos.yml task list is as trivial as Cisco IOS one:

- cisco.nxos.nxos_config:
    src: "{{ config_template }}"

Unfortunately, the Nexus 9300v linecards become active almost a minute after the device boot is completed. We could check whether the Ethernet interfaces are present every time a configuration template is deployed on Nexus 9300v; a more streamlined approach uses a separate task list for initial device configuration in nxos/initial.yml:

- name: Wait for Eth1/1 to appear
    - show interface brief
    - result[0] contains Eth1
    interval: 5
    retries: 20

- cisco.nxos.nxos_config:
    src: "{{ config_template }}"