This document discusses using Azure Functions and Container Instances to interact with a website without using virtual machines. It presents the Page Object Model pattern for maintaining a representation of web pages. Selenium is used to drive a browser within a Docker container to interact with the website. Azure Container Instances host the Docker container in Azure. Polly provides reliability by implementing retry and circuit breaker policies. The solution achieves the goals of interacting with a website daily without additional cost by using serverless Azure Functions and container-based hosting with on-demand billing.

1. Azure Functions and Container Instances
By John Staveley
02/03/2019
https://uk.linkedin.com/in/johnstaveley/
@johnstaveley

2. Overview
The Problem
Selenium and Page Object Model
Azure Functions – developer experience
Docker
SideCar pattern
Azure Container Instances
Polly for reliability

3. Who am I?
John Staveley
Mvc C# Azure Angular developer
Organiser at Leeds Sharp, Leeds Data Science meetups
Second migration into Azure from OnPrem

4. The Problem

5. Problem Requirements
No Api
Interact with the website
– Navigate to the website
– Logon
– Navigate to target web page
– Interact with the page
Do this every day at 8pm without fail
Try and avoid additional cost (No more Vms!)
Framework for solving similar problems

6. Architectural Diagram of MajorDomo

7. Azure Functions
Used to drive the actions
WebJobs bad, Azure functions good
Service plan vs Consumption charging
Azure SDK in visual studio, uses .Net core 2.2
Precompiled function
Triggers: Blob/Table/MongoDb storage, Queue, Timer
Local Function and Storage Emulators for debug
Deploy as web service

8. Why Selenium?

9. Selenium
Used to drive a browser to interact with the website
Supports Chrome, Firefox, IE, Edge etc
Selenium Grid

10. Page Object Model Example 1
Pattern used to ensure a maintainable representation of the
web pages

11. Page Object Model Example 2

12. Page Object Model Example 3

13. MajorDomo Demo
See selenium interacting with the web pages
Code explanation
– Pages using Page Object Model
– How Page object model was used

14. Docker and SideCar pattern
Used to contain the browser
Why? So I can test selenium grid will work locally
Docker – like small Vms
SideCar pattern
Demo: MajorDomo running locally using docker

15. Azure Container Instances
Used to contain the browser in Azure cloud
ACI billing similar to VMs
Docker image: selenium/standalone-chrome
Startup/Shutdown using Azure libraries:

16. Azure Container Instances
Demo: MajorDomo running container in Azure

17. Job done - Celebration!

18. Beer stabilisation

19. Polly Overview
A reliability/resilience framework
.Net/.Net Core
Resilience Policies:
• Retry - ‘Maybe it’s just a blip’
• Circuit Breaker - ‘That system is down / struggling’
• Timeout - ‘Don’t wait forever!’
• Bulkhead Isolation - ‘One fault shouldn’t sink the whole
ship’
• Cache - ‘You’ve asked for that one before!’
• Fallback - ‘If all else fails … degrade gracefully’
Custom Policies - All policies can be combined, for multiple
protection!

20. Polly Implementation
Applying a reliability policy to MajorDomo:

21. Summary
 Page Object Model for a
maintainable model of web pages
 Azure Precompiled Function in the
cloud, same power as a container
without the charging model
 Azure Container Instances SideCar
on demand
 Polly for reliability and resilience
 No VM, Pay as you go for azure
function = No Cost
 Slides on slideshare

22. Further Resources
Selenium:
https://app.pluralsight.com/library/courses/selenium/table-of-
contents
SideCar: https://www.oreilly.com/library/view/designing-
distributed-systems/9781491983638/ch02.html
Control Azure: https://github.com/Azure/azure-libraries-for-
net
Resilience: http://www.thepollyproject.org/
Docker images: https://hub.docker.com/

23. Any Questions?
@johnstavele