Azure Durable Function AppSettings - configuration

Question

I'm trying to create an azure durable function but it's very difficult to find some normal guides on this subject. I've setup the DI and I try to read the settings of the function but it crashes
I have setup an Azure Function project in VS 2019 and added a Durable Orchestrator Function Template. I removed all the "static" references from the class and all seem to work fine until I add the configurationbuilder in the startup file
Can anyone explain to me how this should work or give some guidance, where to find some explanation of the configuration of a durable functions ? What should I have in the host.json , local.settings.json and how this changes be when I publish it on the portal ?
My case is this. The startup file looks like this
using Microsoft.Azure.Functions.Extensions.DependencyInjection;
using Microsoft.Extensions.Configuration;
[assembly: FunctionsStartup(typeof(DurableFunctions.Startup))]
namespace DurableFunctions
{
public class Startup : FunctionsStartup
{
public override void Configure(IFunctionsHostBuilder builder)
{
var settings = new ConfigurationBuilder()
.AddEnvironmentVariables()
.Build();
}
}
}
The host.json is like this
{
"version": "2.0"
}
The local.settings.json
{
"IsEncrypted": false,
"Values": {
"AzureWebJobsStorage": "UseDevelopmentStorage=true",
"FUNCTIONS_WORKER_RUNTIME": "dotnet"
}
}
And the error I get when I start the debugger is this
This is output:
[11/8/2019 10:29:04 AM] A host error has occurred during startup operation '8b80bc94-2b98-408b-895f-c5697430acfd'.
[11/8/2019 10:29:04 AM] Microsoft.Azure.WebJobs.Extensions.DurableTask: Value cannot be null.
[11/8/2019 10:29:04 AM] Parameter name: hostConfiguration.
Value cannot be null.
Parameter name: provider

Answer 1

You want to instead override the ConfigureAppConfiguration method in your FunctionStartup class (https://learn.microsoft.com/en-us/azure/azure-functions/functions-dotnet-dependency-injection#customizing-configuration-sources).
The following example takes the one provided in the documentation a step further by adding user secrets.
public override void ConfigureAppConfiguration(IFunctionsConfigurationBuilder builder)
{
FunctionsHostBuilderContext context = builder.GetContext();
builder.ConfigurationBuilder
.SetBasePath(context.ApplicationRootPath)
.AddJsonFile("appsettings.json", optional: true, reloadOnChange: false)
.AddJsonFile($"appsettings.{context.EnvironmentName}.json", optional: true, reloadOnChange: false)
.AddUserSecrets(Assembly.GetExecutingAssembly(), true, true)
.AddEnvironmentVariables();
}
By default, configuration files such as appsettings.json are not automatically copied to the Azure Function output folder. Be sure to review the documentation (https://learn.microsoft.com/en-us/azure/azure-functions/functions-dotnet-dependency-injection#customizing-configuration-sources) for modifications to your .csproj file. Also note that due to the way the method appends the existing providers it is necessary to always end with .AddEnvironmentVariables().
A deeper discussion on configuration in an Azure Function can be found at Using ConfigurationBuilder in FunctionsStartup

Answer 2

Did you get a response to this?
Did you try adding the local settings from the json, before the Environment Variables?
var config = new ConfigurationBuilder()
.SetBasePath(context.FunctionAppDirectory)
// This gives you access to your application settings in your local development environment
.AddJsonFile("local.settings.json", optional: true, reloadOnChange: false)
.AddJsonFile("secret.settings.json", optional: true, reloadOnChange: false)
// This is what actually gets you the application settings in Azure
.AddEnvironmentVariables()
.Build();
I am having trouble when I deploy, I have set up a variable group yet they are not being picked up.