"Migrating to the Isolated worker process in Azure Functions" provides an overview of serverless computing and different hosting models, with a focus on migrating to the isolated worker process in Azure Functions. The presentation covers the benefits of the isolated worker process, including fewer conflicts, full control of the process, and dependency injection. It also includes demos and practical steps for migrating existing .NET applications to the isolated worker process. The presentation aims to help developers modernize their applications and prepare for future versions of .NET.

1. Migrating to the Isolated worker
process in Azure Functions
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
Azure Functions
service
Code or container
App Service plan
Windows or Linux
Azure Functions
service
Code
Consumption plan
Windows or Linux
Non-Azure hosts /
on-premises
Code
App Service on Azure
Stack
Windows
Additional Azure
hosts
Container
AKS, Service Fabric, …
●●●
Linux
Non-Azure hosts /
on-premises
Container
Linux
●●●
K8s, raw VMs, & more
Development Hosting
IoT devices
Container
Azure IoT Edge
Linux
Local dev machine
Code or container
Core Tools + favorite
editor
Windows, macOS, or Linux
●●●
+
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
●●●
Azure Functions
service
Premium plan
Windows or Linux
Code or container
Functions everywhere Azure Functions
AzureContainer Apps
Azure Functions
Flex Consumption
(preview)

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. In-process Model
Trigger/Input Binding Payloads
Output Binding Payload
Functions Host
In-process
Worker

8. Isolated Worker Model
Trigger/Input Binding Payloads
Output Binding Payload
Functions Host Isolated Worker
Request Payload
Response Payload

9. 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.

10. 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
 End of support
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, .NET 8, and .NET 9
(preview)
 The future
Which one do I use?
Details:
https://learn.microsoft.com/en-us/azure/azure-functions/dotnet-isolated-in-process-differences

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

12. Azure Functions .NET Roadmap
GA: Aug
2024

13. 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.

14. Demo
Creating Azure Function app using Isolated worker process

15. Migrating to the Isolated worker process
.NET 6 In-process .NET 8 Isolated
Project file changes

16. Migrating to the Isolated worker process
.NET 6 In-process .NET 8 Isolated
• 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.Sd
k

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

18. 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.

19. 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.

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

21. What we covered
 Comparison of in-process and isolated worker processes.
 Benefits of the isolated worker process and migration path.
 Migration to .NET 8 with isolated worker.

22. Closing
 The isolated worker is in position to tackle things that can’t be
done with the in-process model.
 Support ends for the in-process model on November 10, 2026.
 Begin planning your migration to the isolated worker model in
advance of this date.

23. References
 Azure functions runtime versions overview
 Develop C# class library functions using Azure Functions | Micro
soft Learn
 .NET on Azure Functions – September 2024 roadmap update
 .NET Upgrade Assistant
 Support ends for the in-process model on November 10, 2026
 Azure Functions Flex Consumption high scale vnet
networking (microsoft.com)

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

25. Thanks for joining
Time for Q&A