| author | mattchenderson |
|---|---|
| ms.service | azure-functions |
| ms.topic | include |
| ms.date | 03/28/2024 |
| ms.author | mahender |
The Program.cs file replaces any file that has the FunctionsStartup attribute, which is typically a Startup.cs file. In places where your FunctionsStartup code would reference IFunctionsHostBuilder.Services, you can instead add statements within the .ConfigureServices() method of the HostBuilder in your Program.cs. To learn more about working with Program.cs, see Start-up and configuration in the isolated worker model guide.
The default Program.cs examples previously described include setup of Application Insights. In your Program.cs, you must also configure any log filtering that should apply to logs coming from code in your project. In the isolated worker model, the host.json file only controls events emitted by the Functions host runtime. If you don't configure filtering rules in Program.cs, you might see differences in the log levels present for various categories in your telemetry.
Although you can register custom configuration sources as part of the HostBuilder, these similarly apply only to code in your project. The platform also needs trigger and binding configuration, and this should be provided through the application settings, Key Vault references, or App Configuration references features.
After you move everything from any existing FunctionsStartup to the Program.cs file, you can delete the FunctionsStartup attribute and the class it was applied to.