Yaml for network engineers

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Is there any difference if i use one space, two or four spaces per indent level in YAML? For example 4 spaces for nesting maps1 space per list item etc?? I am writing a yaml configuration file for elastic beanstalk. Although i have valid yaml in YAML Validator elastic beanstalk seems to understand a different structure. There is no requirement in YAML to indent any concrete number of spaces. There is also no requirement to be consistent.

So for example, this is valid YAML:. The YAML spec for v 1. In YAML block styles, structure is determined by indentation. In general, indentation is defined as a zero or more space characters at the start of a line.

To maintain portability, tab characters must not be used in indentation, since different systems treat tabs differently. Note that most modern editors may be configured so that pressing the tab key results in the insertion of an appropriate number of spaces. The amount of indentation is a presentation detail and must not be used to convey content information. So you can set the indent depth to your preference, as long as you use spaces and not tabs.

Interestingly, IntelliJ uses 2 spaces by default. Learn more. YAML How many spaces per indent? Ask Question. Asked 3 years, 2 months ago.

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Are there any specific rules for space numbers per Structure type??While the solution did work, creating scripts from scratch using a programming language can be a daunting task for network engineers. Luckily for us, there are already tools in place that we can leverage to do the heavy lifting for us.

Today we will look at Ansible to generate network device configurations from templates. Ansible is an automation framework that was first developed as a way for server administrators to automate tasks such as deploying software and making configuration changes.

It uses the SSH protocol to do this. The aspect of Ansible that has allowed network engineers to embrace it is the fact that it is agent-less. That means it does not require us to install software on our devices in order to utilize it.

Ansible also happens to be written in Python, so we can leverage Jinja2 for templating. The way that Ansible normally works is by connecting to the devices within an inventory file, and then copying Python code onto that device and running it.

Network Automation: Template Configurations with Jinja2 and YAML

Instead, Ansible will run locally, and the Python code will be executed by the host running Ansible. These pieces of Python code are known as Ansible modules. Think of Ansible Modules as plugins that assist you in your automation tasks. Ansible uses a YAML file known as a playbook. A playbook can easily be described as a list of tasks that need to be accomplished for that particular automation routine.

YAML allows playbooks to be complex in what is accomplished, but simple to read and understand. The only other file required to run an Ansible playbook is the inventory file. The inventory file contains a list of devices that the playbook will be run on. Although Ansible will be executing the Python code locally when interacting with network devices, the inventory will still list the devices that will be interacted with remotely.

When you run a playbook you can explicitly name the inventory file. You can also break up your inventory file into different parts. This allows you to use a single inventory file, but break up the devices within it into different groups.

Ansible is available for Linux, macOS, and Windows beta. For Windows you can use the Linux Subsystem for Windows, but it is only in beta and not officially supported by Ansible or Microsoft Instructions Here. For Linux, you can easily install Ansible via your package manager. The first thing we are going to do is create our Jinja2 templates. We will be using two templates in this example to show how multiple templates can be linked together to create a single configuration.

This can allow you to make your configurations modular so that you can update only a particular module and version control that rather than the configuration as a whole. This comes in handy when certain parts of the configuration such as local emergency account credentials change more frequently than others disabling unused services for security purposes. We will be using the following templates: baseline.

Below is the configuration each:. When I previously used a python script with the Jinja2 template, I had a separate. Ansible playbooks are also able to use variables, so we can combine both variables into a single location. Ansible will look for this folder when executing a playbook and variables are used. Now we are ready to create variable files. The most basic variable file is named all. We can also create.In a previous postI went over the basics of using Jinja to create templates for network configurations.

This time I will be showing some examples of using YAML to store information about our network devices and using it to feed information to jinja.

YAML is a data serialization language that is also very easy for humans to read. Often used to store data or information, such as settings for a program. Of course, it also happens to be quite good for storing network information, specifically configuration items for a device. You can think of it like a folder structure in an OS like windows or macOS. You may have a folder for documents, which contains another folder for photos which may contain another folder for vacation photos specifically.

Not only is it easy for us to read, but its also really easy for python to parse. Having data structured in such a way that we can understand and use programmatically is quite useful. Its difficult to coherently describe nested objects with multiple layers, hence giving multiple examples in hopes one of them will stick.

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Formatting is pretty important here, as the indentation level indicates a sort of parent child relationship. Now, theres one more way I want to present YAML, and thats how it looks after python has consumed it. Once thats done import the module, open the file containing your YAML, and use the yaml. I used prettyprint to get a better formatted output to display here, but its not required of course.

Heres the output:. If you are pretty familiar with python, you will probably now realize how using YAML provides python with good data to parse. Its your basic python data structure: lists and dictionaries. You can easily loop through any lists and use specific values from the dictionary key value pairs to plug in variables into a config.

Also remember that some data types in python are unordered, so its not necessarily going to come out in the same way it went in. You can use it to describe a single device or many devices. Lets quickly go through an example of using YAML to feed a jinja template.

yaml for network engineers

Check out this jinja template below:. In Jinja, you can actually use some common python procedures such as for loops and if statements.

This is to prevent that line from showing a blank line in your output and messing up the formatting. Jinja does require you indicate the end of your for loops and if statements, which python its self does not require. The other thing thats a little different here is our variables. It will become a little more clear when I show the python code below, but this is because we are passing lists and dictionaries into jinja instead of plain string variables.

We can then extract the values we need to complete our configuration by access the data stored in each key of the dictionary.Network automation and programmability is one of the hot topics in networking today.

It is one area that I want to focus on this year and become very familiar with. Although it is only available in a pre-release incomplete version, if you have a Safari Books subscription I highly recommend checking it out. This book not only is extremely easy to ready, but it gives the high level ideas and theory that I feel is desperately needed for us network engineers. This whole programming idea is foreign to a lot of us, and just jumping right into coding can be a very daunting and intimidating task.

This book is what gave me the clarity to feel confident enough to dive into automation. In this blog post I will utilize a code example from the book that will allow you to automate network configuration templates. It is easy, low hanging fruit that will allow you to get your feet wet, and at the same time actually put this whole progamming and automation to practical use that every engineer can relate to. Today, most baseline templates used for device configuration is stored one of two ways: a text file or excel spreadsheet.

I highly recommend this podcast to get some insight into how we are pretty inefficient into how we run things today. By switching over to a more programatic and automated way to do configuration templates, a lot of the error prone mistakes can be removed, and it also helps you think of managing your network in a different way. It also allows you to try out automation and programming without the fear of actually breaking the network.

Here we will just be creating configurations. Once we start diving in and using Jinja2, it will become very clear what it is and how we can leverage it. To install Jinja2, you will first need to have Python installed. If you are running Linux or macOS, Python should already be installed. I would recommend version 2.

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Jinja2 works with 2. The easiest way to install Jinja2 is using pip. In order to really harness the power of using templates, we need a way to feed data into the template so that it knows how to populate the template.

YAML allows us to provide data in a structured way. To understand the importance of this, lets think about how we get data from Cisco devices running IOS.

yaml for network engineers

It is simply a wall of text. The table has all the information needed, right? I can see which interfaces have an IP address, and which ones have a status of up and protocol up, correct? Unfortunately, none of the data itself is related. It is just printed out. Other than a human reading it, that text serves no purpose and cannot be easily manipulated. If you wanted to create a script, you would have to come up with a way to search the wall of text and manipulate it to your needs.

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The first three dashes signify this file as a YAML file. The rest is the same exact information as the first line of the CLI output, but in this format a programming language can actually understand the information. It will know that the IP-Address is set to If we were able to get this kind of data from the router, then we could easily make a script that parses the information and looks for criteria matches. This is the power that YAML and other structured data sets bring to the table for network automation.

If you have ever created a script that had to parse text, known as screen scraping, you will understand how powerful structured data can be for the networking world.Do you want to program networks using Ansible, but not sure where to start? Well, this course will show you how you can start programming Cisco networks within 30 minutes. This course was created for network engineers.

There are too many other Ansible courses out there that try to make network engineers server administrators. They concentrate on server administration, installation of software packages and other server admin tasks.

This course is practical. I won't talk about programming in abstract terms and make you wait before you can start automating networks. You will see demonstrations of the configuration of both Cisco routers and switches in GNS3.

Learn how you can use Ansible to troubleshoot networks! Use a single Ansible command to retrieve mac address table information from multiple switches in seconds. Then pipe the output to a regular expression to filter down to a single MAC address. You will never troubleshoot networks the same way again! This course shows you practical examples of using Ansible to programmatically configure Cisco network devices rather then just talking about it.

The days of configuring Cisco networks only with the command line interface CLI are drawing to a close. You need to add network programmability using Ansible to your skill set. Don't reinvent the wheel. Use the tools available to you to quickly and easily automate your networks. Another plus about this course is that David keeps it really interesting throughout by constantly introducing new technologies and methods to improve your coding skills.

This course really is different from the rest of the python courses out there, and you really learn something new every lecture, and for that reason, this course is worth every penny! An invaluable resource for network engineers getting started in the field of Python network programming and automation.

The best money I have spent on training in a long time. The instructor is clear and precise in his delivery, a complete pro. I look forward to future additions to this course. Many thousands of engineers like you use his tools and training on a regular basis. David has developed over 20 courses for HP which are used worldwide. He has also personally developed Cisco engineer utilities such as the VPN Config Generator, software, training materials, EBooks, videos and other products which are used throughout the world.

LinkedIn: linkedin. The coupon code you entered is expired or invalid, but the course is still available! This course is different.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. If nothing happens, download GitHub Desktop and try again. If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again. A "Python for network enginners" course.

It is useful to network engineers with no python programming knowledge, who wants to use python to manage junos devices. This is a hands-on training, with step-by-step instructions and many basics examples.

Useful Python Libraries for Network Engineers

The course covers an introduction to Python programming, it includes also the PyEZ library to interact with JUNOS devices as well as an overview of some other Python modules to manipulate IP addresses, files, regular expressions, templates and rest calls.

The presentations are available into this repo - Python-for-network-engineers.

Ansible for Networking

All the scripts are available into this project. The examples and code in this document are for learning and educational purposes. The samples were created with the goals of clarity and ease of understanding. If you are writing code for a real application, you would write some code differently Skip to content.

Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Sign up. Python hands-on training for network engineers. How to automate Junos with Python. Python Branch: master. Find file.

yaml for network engineers

Sign in Sign up. Go back. Launching Xcode If nothing happens, download Xcode and try again. Latest commit. Latest commit 0df Oct 18, What to find in thos project A "Python for network enginners" course. Presentations The presentations are available into this repo - Python-for-network-engineers.

You signed in with another tab or window. Reload to refresh your session. You signed out in another tab or window. Jun 20, Jul 18, Update readme. May 28, Update logging. May 24, Oct 10, Thank you to Jeremy for those late tweaks before getting this posted! Thanks to Kirk Byers kirkbyers as well - he was also gracious enough to respond to clarify a few things and assisted with this post indirectly. There have been numerous articles written that describe the what and the why of Devops.

Imagine working in an environment where automation is embraced? We know most networks are not leveraging nearly any type of automation. While we usually talk about engineers of all types not embracing automation, is the harsh reality most organizations are from having the right culture to embrace automation?

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What if there was a way to start testing network automation without taking a risk in a production environment? There are four leading configuration management solutions being used by the Devops community — they include Puppet, Chef, Ansible, and Salt.

Are you the kind of person that has to build out configurations? Maybe load OSs on new devices or maybe perform an OS upgrade once or twice per year? Maybe you need to quickly deploy a new change across several devices? Too good to be true? Keep reading. As an aside…as you start thinking about network provisioning and automation, think about tools built for network provisioning.

Are there many out there today focused on bootstrap provisioning? Being agentless simplifies management by eliminating the need to deploy and manage the agents. This makes Ansible a solid choice to begin testing with. First, the device needs to support SSH. Ansible uses SSH to login to remote devices to execute changes.

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The second thing is the device needs to support Python. Ansible logs into the device, drops in an executable module typically Pythonexecutes it, and then removes the module. On a side note, Jeremy is already working on this for Juniper devices. More funky names, I know. Since Ansible leverages YAML and integrates with jinja2 templates, they are important to cover though. There needs to be a way to define configuration files as templates.

As defined on the official jinja site, Jinja2 is a templating language for Python. I know I know, What the heck does that mean? Imagine you have a bunch of. You need to update the NTP server in all of your files.

What do you do? The templating language is syntax that occurs in the curly brackets in the actual template files that will still resemble general config files. This will make more sense below. You need a place to store the variables that get merged into those Jinja2 templates. YAML is a great middle ground, and appears to be the defacto language used by most modern DevOps tools today. The great thing about YAML is that is natively imports into variables within the tools that you can access directly; so no writing code just to get at the data you want like you have to do with CSV files or XML.

Please note I am not really going to cover the process of installing or running Ansible. Click the link for the ansible-vsrx-demo.

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