Azure Functions support two different worker processes. With the introduction of .NET 5, Microsoft decided to make an isolated worker process, which is the only future model, and we s developer need to gradually move in that direction. In this session, I show you how to build Azure Functions with the Isolated worker process in .NET 7. He will also dive into the .NET 8 roadmap and how that affects Azure Functions.

1. Getting started with Azure Functions
using Isolated worker process
Callon Campbell
Microsoft MVP | Azure
@flying_maverick

2. About me
Callon Campbell
Azure Architect | Developer
Adastra
Microsoft MVP | Azure
 20 years enterprise development with Microsoft technologies – .NET (C#),
Azure, ASP.NET, Desktop, SQL, and Mobile
 Passionate about serverless and cloud-native application development,
with focus on app migration and modernization, app integration and data
analytics
 Blogging at https://TheFlyingMaverick.com
 Speaker at community events and meetups
 Organizer of “Canada’s Technology Triangle .NET User Group” in
Kitchener, Ontario

3. Agenda  Overview of serverless
 Different hosting models
 Preparing for .NET 8
 Demos
 Wrap-up
 Q&A

4. Azure Functions
Run code when events occur
Event-driven scaling
No infrastructure management
Consumption pricing with free grant

5. Platform
Application
delivery
Operating
system
●●● ●●●
●●●
+
https://github.com/azure/azure-functions-host
(+other repos)
Azure Functions
host runtime
Azure Functions
Core Tools
Azure Functions
base Docker image
Azure Functions
.NET Docker image
Azure Functions
Node Docker image
●●●
Functions everywhere

6. .NET functions hosting models
In-process
 Your function code runs in the same process as the Functions host
process. Only supports LTS versions of .NET
Isolated worker
 Your function code runs in a separate .NET worker process.
 This is what all non .NET languages use.

7. Why .NET Functions isolated worker process?
 When it was introduced, Azure Functions only supported a tightly
integrated mode for .NET functions called in-process.
 Your code runs in the same process as the host, resulting in a tight
coupling between the host process and the .NET function app.
 In-process function can only run on the LTS version of .NET.
 Non-LTS required you to use an isolated worker process that debut
in .NET 5.
 Isolated worker process aligns with the evolution of .NET.

8. Comparing Azure Functions hosting models
In-process
 Migrate from .NET Core 3.1 in-
process
 Need Durable Functions Entities or
“rich” SDK type bindings that are
 Support for .NET 6 and .NET
Framework 4.8
 Performance and cold-start
optimization
Isolated worker
 Migrate from .NET 5 or .NET 6
isolated process
 Added support for middleware
 Support for .NET 6, .NET 7, .NET
Framework 4.8, and .NET 8
(preview)
Which one do I use?
Details: https://learn.microsoft.com/en-us/azure/azure-functions/dotnet-isolated-in-process-differences

9. Comparing available Azure Function triggers
.NET 6 In-process .NET 7 Isolated worker

10. Azure Functions .NET Roadmap
In-process
Isolated process
.NET 5 .NET 6 LTS .NET 7 .NET 8 LTS
.NET Core 3.1 LTS .NET 6 LTS
with Durable Functions
Nov 2021
Nov 2022 Nov 2023

11. Strengths of Isolated worker process
 Fewer conflicts: Assemblies used in your app won't conflict with
different version of the same assemblies used by the host process.
 Full control of the process: You control the start-up of the app and
can control the configurations used and the middleware started.
 Dependency injection: Use current .NET behaviors for
dependency injection and incorporating middleware into your
function app.
 Target new versions: Easily target new versions of .NET as they
become available.

12. Demo
Creating Azure Function app using Isolated worker process

13. Migrating to the Isolated worker process
.NET 6 In-process .NET 7 Isolated worker
Project file changes

14. Migrating to the Isolated worker process
.NET 6 In-process .NET 7 Isolated worker
• The packages for these extensions will all be under the
Microsoft.Azure.Functions.Worker.Extensions prefix.
• Be sure to install the latest stable version of any packages you are targeting.
• Your application should not reference any packages in the Microsoft.Azure.WebJobs.*
namespaces. If you have any remaining references to these, they should be removed.
 Microsoft.NET.Sdk.Functions  Microsoft.Azure.Functions.Worker
 Microsoft.Azure.Functions.Worker.Sdk

15. Migrating to the Isolated worker process
Code changes: new Program.cs
file
In-process Isolated worker
[FunctionName("Function1")] [Function("Function1")]
Code changes: Function
attribute

16. Migrating to the Isolated worker process
In-process Isolated worker
Configuration changes
"FUNCTIONS_WORKER_RUNTIME":
"dotnet"
"FUNCTIONS_WORKER_RUNTIME":
"dotnet-isolated"
Tip
If you are moving to an LTS or STS version of .NET, the .NET Upgrade Assistant can be used to
automatically make many of the changes mentioned.

17. Update your function app in Azure
Upgrading your function app to the isolated model consists of two
steps:
1. Change the configuration of the function app to use the isolated model by
setting the FUNCTIONS_WORKER_RUNTIME application setting to "dotnet-
isolated". Make sure that any deployment automation is similarly updated.
2. Publish your upgraded project to the upgraded function app.
Use a staging slot to test and verify your upgraded code /
configuration. Then perform a swap operation when ready to deploy
to the production slot.

18. Demo
Migrating an Azure Function app to Isolated worker process

19. What’s coming?

20. Azure Functions .NET 8 roadmap
 Isolated worker process reaching feature parity.
 Isolated worker will be initially supported on .NET 8 release.
 In-process for .NET 8 will be the last LTS release and will be
released slightly after the .NET 8 release.

21. .NET 8 (preview) for Azure Functions
 Preview support for .NET 8 function apps is currently limited to Linux
applications.
 Requires .NET 8 Preview SDKs in Visual Studio (Visual Studio 2022
Preview).
 Performance optimizations is coming…
 Placeholder for cold-start
 Optimized executor
 ReadyToRun (form of AOT)
 .NET 8 AOT compilation

22. Demo
Sneak peak at Azure Functions in .NET 8

23. What we covered
 Comparison of in-process and isolated worker processes.
 Benefits of the isolated worker process and migration path.
 Sneak peak at .NET 8

24. Closing
 The isolated worker is in position to tackle things that can’t be done
with the in-process model.
 Try the isolated worker process and plan your migration.
 If performance and certain key features are critical, stick to the in-
process model for the time being since with .NET 8 it will still be
supported.

25. References
Azure functions runtime versions overview
C# Azure Functions in an isolated worker process
.NET on Azure Functions — August 2023 roadmap update
.NET Upgrade Assistant

26. Let’s Connect
https://LinkedIn.com/in/CallonCampbell
@flying_maverick
Callon@CloudMavericks.ca
https://GitHub.com/CallonCampbell

27. Thanks for joining
Time for Q&A