Ansible: Parse Cisco commando ouputs with TEXTFSM

Table of Contents

To parse outputs of commands in Ansible you can use TEXTFSM. You need to install textfsm with pip.

TEXTFSM is a template based parser for commandline outputs.

Install of the required packages
#

python -m virtualenv venv
source venv/bin/activate
pip install ansible ansible-pylibssh textfsm

Example: TEXTFSM parser file inventory_cisco_ios.textfsm
#

There are already ready-made templates for many network manufacturers such as Cisco, I have the example here from networktocode/ntc-templates (Github), as a fork directly from me lanbugs/ntc-templates: TextFSM templates for parsing show commands of network devices (github .com) on Github.

Value NAME (.*)
Value DESCR (.*)
Value PID (([\S+]+|.*))
Value VID (.*)
Value SN ([\w+\d+]+)

Start
  ^NAME:\s+"${NAME}",\s+DESCR:\s+"${DESCR}"
  ^PID:\s+${PID}.*,.*VID:\s+${VID},.*SN:\s+${SN} -> Record
  ^PID:\s+,.*VID:\s+${VID},.*SN: -> Record
  ^PID:\s+${PID}.*,.*VID:\s+${VID},.*SN: -> Record
  ^PID:\s+,.*VID:\s+${VID},.*SN:\s+${SN} -> Record
  ^PID:\s+${PID}.*,.*VID:\s+${VID}.*
  ^PID:\s+,.*VID:\s+${VID}.*
  ^.*SN:\s+${SN} -> Record
  ^.*SN: -> Record
  # Capture time-stamp if vty line has command time-stamping turned on
  ^Load\s+for\s+
  ^Time\s+source\s+is

Example: Ansible playbook collect_inventory.yml
#

The module ansible.utils.cli_parse is used and as a parser ansible.utils.textfsm. The textfsm file that can parse the output is specified as template_path.

---
- name: Collect invenory of device
  hosts: testswitch
  gather_facts: False

  vars:
    ansible_connection: network_cli
    ansible_network_os: ios

  connection: network_cli
  
  tasks:
    - name: Collect inventory
      ansible.utils.cli_parse:
        command: show inventory
        parser:
          name: ansible.utils.textfsm
          template_path: inventory_cisco_ios.textfsm
      register: inv

    - name: Debug
      debug:
        msg: "{{ inv }}"
```

##### Example: inventory.ini
```ìni
[devices]
testswitch ansible_host=10.1.1.1 ansible_user=cisco ansible_ssh_pass=cisco
```
##### Output
```
(venv) lab@labhost:~$ ansible-playbook -i inventory.ini collect_inventory.yml                                                 

PLAY [Collect invenory of device] ********************************************************************************************************************************************

TASK [Gather invenory] ***************************************************************************************************************************************************
ok: [testswitch]

TASK [Debug] *************************************************************************************************************************************************************
ok: [testswitch] => {
    "msg": {
        "changed": false,
        "failed": false,
        "parsed": [
            {
                "DESCR": "WS-C3560CG-8PC-S",
                "NAME": "1",
                "PID": "WS-C3560CG-8PC-S",
                "SN": "FOC1234A0ZZ",
                "VID": "V03  "
            }
        ],
        "stdout": "NAME: \"1\", DESCR: \"WS-C3560CG-8PC-S\"\nPID: WS-C3560CG-8PC-S  , VID: V03  , SN: FOC1234A0ZZ",
        "stdout_lines": [
            "NAME: \"1\", DESCR: \"WS-C3560CG-8PC-S\"",
            "PID: WS-C3560CG-8PC-S  , VID: V03  , SN: FOC1234A0ZZ"
        ]
    }
}

PLAY RECAP ***************************************************************************************************************************************************************
testswitch             : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   
```

In inv.parsed is now a list of dictionaries with the parsed data. In inv.stdout_lines are the originals of the return.

Now you could e.g. write that in a CSV file, here is an addition for the playbook:

```bash
    - name: Add to report
      lineinfile:
        insertafter: EOF
        dest: inv_report.txt
        line: "'{{ inventory_hostname }}','{{ item.NAME|default('no name') }}','{{ item.DESCR|default('no descr') }}','{{ item.PID|default('no pid') }}','{{ item.SN|default('no sn') }}','{{ item.VID|default('no vid') }}'"
      with_list: "{{ inv.parsed }}"
      when: inv.failed is false
      delegate_to: localhost
```