Validation, Error Handling and Testing

Have you completed the Ansible Deep Dive module of the Ansible for Networking Engineers online course? If haven't, please do it now, or you'll have problems understanding the material discussed in this module.

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In this section you’ll learn how to:

• Write fail-safe playbooks
• Recover from Ansible module failures and report them
• Use Ansible logging and debugging tools
• Debug individual components of your Ansible playbooks (tasks, plays or modules/plugins)
• Build and automate unit tests
• Validate input data and device state

The "Software Testing" part of this section has been significantly improved in 2022, the rest of the materials were delivered in one of the 2017 online courses.

Once you have a reliable test suite, you can start implementing continuous integration (automated merging of changes to the baseline code branch), delivery (having a deliverable environment at all times) and deployment (automated deployment of the deliverable environment).

GitLab CI is one of the commonly-used networking-focused continuous integration tools due to its agent-based architecture.

In this section Pete Lumbis explained how he uses GitLab CI to test his network automation scripts and device configurations.

Kristian Larsson described a testing methodology based on the approach his team is using to test the network automation system they're building for Deutsche Telekom Terastream project.

He started with unit and system tests, described various approaches to device mocking, explained how to do end-to-end system tests, and shown how you can use vrnetlab (an open source virtual network lab environment focused on testing use cases) in Continuous Integration pipeline.

In the second part of his presentation he described how you could test correctness of BGP configurations with docker-based BGP feeds, and concluded with a discussion of robustness and feature flags.

You’ll add data validation and error handling to the service deployment playbook you created during Week 4, and create unit tests to test your new code with a variety of invalid inputs.

When you automate, you want to make sure that you are not automating bugs and mistakes, thereby making them spread across your environment. That is why you want to have a proper testing pipeline in place!

In his presentation, Gabriele Gerbino gives some practical examples building a simple testing pipeline by using Travis-CI and VMs/containers to make sure that you can sleep better once you hit the DEPLOY red button.

David Barroso explained how to design and write an application focusing on three aspects; scalability, maintainability, and reliability.

He described design principles, tools, and patterns you can use to grow your applications without compromising long-term quality, and increase confidence and speed when developing new features or changing existing ones.

In the second half of the presentation, David illustrated these principles with a simple application that generates interface- and BGP configuration from a network data model.

Explore validation with NAPALM, test-driven development and distributed testing tools. You might also be interested in tools that make your Ansible development less error-prone.