I’ve written about NTC-Ansible a couple of times already and thought now would be a good time to run you through the installation process. The github page provides some great information on the process, but I’d like to add a few extra details in this post.
Note that there are two ways in which you can install custom modules. They work as well as one another so it’s up to you which you choose.
Now that we’ve covered how TextFSM work and how it can be used to record useful information from device outputs, it’s time to move our focus on how we use TextFSM templates in Ansible.
ntc_show_command module, we’re able to “get structured data from devices that don’t have an API”. As I’ve touched on in previous posts, it does this through the use of TextFSM templates which can be found here. I’ll cover how to write your own templates in a future post but for now I’ll focus on how to use the existing templates.
In my previous post I covered how to to download, install and test TextFSM. In this post I’ll demonstrate how to write your own template files so that you can create (and hopefully contribute!) them if a suitable one does not already exist.
It is worth mention that the examples in this post are extremely basic. I’ve done it this way on purpose because I’m only trying to demonstrate how to use TextFSM, not how to write regex. I feel that trying to do both in a single post would cause unnecessary confusion for those who are not familiar with either.
As I mentioned in my previous post, NTC-Ansible uses TextFSM templates to allow you to convert your CLI outputs to JSON and then access the data in an API-like fashion.
In this post I’ll cover how to run TextFSM templates against CLI outputs.
To get started, download the latest version of TextFSM using the ‘git clone’ command:
will@ubuntu:/tmp$ git clone https://github.com/google/textfsm.git
Cloning into 'textfsm'...
remote: Counting objects: 105, done.
remote: Total 105 (delta 0), reused 0 (delta 0), pack-reused 105
Receiving objects: 100% (105/105), 65.15 KiB | 0 bytes/s, done.
Resolving deltas: 100% (45/45), done.
Checking connectivity... done.
In this series of posts I will cover how you can create your own API-like functionality for devices which do not have APIs built into them. Before I get started though, for those of you who don’t know what an API is, here’s Wikipedia’s description:
“Just as a graphical user interface makes it easier for people to use programs, application programming interfaces make it easier for developers to use certain technologies in building applications. By abstracting the underlying implementation and only exposing objects or actions the developer needs, an API reduces the cognitive load on a programmer.”