New Lesson - Using Jinja for Config Templates

[ShrutiVPawaskar]

Introduction to Jinja2 and Junos PyEz

Part 1 – Intro to Jinja2

Discusses Jijna2 syntax

• Template rendering
• {% if %}
• {% for %}
• {% set %}

Part 2 – Into to PyEz

• Connecting to a remote Junos device.
• Getting configuration from the Junos device.
• Loading configuration to the Junos device.

Part 3 –Configuring Junos Device using PyEz and Jinja2 Template

• Creating Jinja2 template for Junos configuration.
• Rendering Jinja2 template.
• Pushing config to the Junos device using PyEz config module

Part 4 - Optimizing Configuration Push

• Use Junos PyEz inbuilt function to render Jinja2 template and configure a single device
  with Config(dev, mode='private') as cu:
  cu.load(template=template, template_vars=template_vars, format='text')

Part 5 –Configuring multiple Junos devices using Jinja2 template

• Use a single Jinja2 template
• Use YAML file or Python dictionary as variables
• Pushing basic config like hostname to multiple devices.

Closes nre-learning/antidote#72

[shahbhoomi]

@Mierdin Can you please review our lesson.

[Mierdin]

This is a great start! I have a few comments, most of which are suggestions you can simply accept if you wish. Most of my other comments are structural or syntactic - for instance you're using italics instead of a code snippet. Generally my concerns are about consistency - if you're using a certain style in the beginning, such as the way you're referring to code snippets or examples, do that consistently across the lesson. I didn't get all the way through the PR - I stopped at lesson 3 because I didn't want to drown you with a billion comments on the same thing. Could you go back and try to apply those comments across the lesson as a whole? I think it will end up looking a lot better on the front-end.

Also - have you tested this out locally? The reason I ask is that the utility container doesn't currently have jinja installed. I am hoping you've instead tested this with your own image. In any case, the users will want to have access to jinja, so please add this to images/utility/requirements.txt in this PR.

Thanks to you both for your hard work on this - ping me here or on Slack for any questions.

[shahbhoomi]

@Mierdin we have made the proposed changes in stage 1 and 2 and we also reviewed the stage 3 and stage 4. Could you please check it now?

[ShrutiVPawaskar]

@Mierdin I have changed the syntax snippet to three-backticks (```) to and have renumbered the snippet accordingly.

Issue:

 Okay. Please use the three-backticks (```) here anyways so that it renders correctly - you don't have to put a button here. Note that the javascript for the run this snippet button still counts this so you'll have to update your indices for the other places you have this button appropriately.

[ShrutiVPawaskar]

@Mierdin We have added a new stage in the lesson based on Jeremy's recommendation. Hence, moved parts around in other lessons.

[Mierdin]

This is really good. Thanks for working on this - I imagine this will rapidly become one of the most popular lessons - I often blow network engineers' minds with what can be done with Jinja.