Configuration in isolated mode

[phatcher]

I'm trying to change my .NET 6 Azure Functions V4 project to isolated mode but seem to be missing some stuff

1. How to get the ApplicationRootPath or Environment values in either ConfigureHostConfiguration/ConfigureAppConfiguration
2. How to get the IConfiguration in ConfigureServices

Previously I could use the IFunctionConfigurationBuilder/IFunctionsHostBuiler GetContext() method but I can't find an equivalent

[davidpetric]

Hi @phatcher,

1. ConfigureAppConfiguration has an overload which takes an Action of type: Action<HostBuilderContext, IConfigurationBuilder> configureDelegate)
   • I think ApplicationRootPath now is accessible from the HostBuilderContext type and now has the name ContentRootPath,
   • You can access the Environment values by using the static class Environment or if you need something which was not declared there you can use string myCustomEnvVariable = Environment.GetEnvironmentVariable("my_custom_env_variable ")

Example for ConfigureAppConfiguration

    .ConfigureAppConfiguration((hostBuilderContext, builder) =>
    {
        IHostEnvironment hostingEnvironment = hostBuilderContext.HostingEnvironment;
        string contentRootPath = hostingEnvironment.ContentRootPath;

        IConfiguration configuration = hostBuilderContext.Configuration;

        string myCustomEnvVariable = Environment.GetEnvironmentVariable("my_custom_env_variable");

        // Example of configuring
        // local.settings.json, environment variables, visual studio user secrets.
        builder.SetBasePath(Directory.GetCurrentDirectory())
                .AddJsonFile("local.settings.json", optional: true, reloadOnChange: true)
                .AddEnvironmentVariables()
                .AddUserSecrets(Assembly.GetExecutingAssembly(), optional: true);
    })

2. To get IConfiguration in ConfigureServices you need to use ConfigureServices(Action<HostBuilderContext, IServiceCollection> configureDelegate); overload.

Example:

    .ConfigureServices((hostBuilderContext, services) =>
    {
        IConfiguration configuration = hostBuilderContext.Configuration;
        string sqlConnectionString = configuration.GetValue<string>("SqlConnectionString");

        services.AddScoped<IUserService, UserService>();
    })

[phatcher]

@davidpetric Thanks for that, it's unblocked me from proceeding - I think something along these lines needs to go into the migration guide as finding the overloads is a bit non-obvious.

Just need to see if it works now and whether I can easily get over the lack of INameResolver ;-)

[satvu]

Flagging this as an opportunity to improve samples/docs.

[pregress]

The answer in this issue is indeed the correct one, using Directory.GetCurrentDirectroy() to set the configurationbuilder base path.

The documentation here is out of date, not relevant for isolated workers: https://learn.microsoft.com/en-us/azure/azure-functions/functions-dotnet-dependency-injection#customizing-configuration-sources

Best to also add the sample there:

https://learn.microsoft.com/en-us/azure/azure-functions/dotnet-isolated-process-guide

var host = new HostBuilder()
    .ConfigureFunctionsWebApplication()
    .ConfigureAppConfiguration((context, configBuilder) =>
    {
        configBuilder
            .SetBasePath(Directory.GetCurrentDirectory())
            .AddJsonFile($"appsettings.{context.HostingEnvironment.EnvironmentName}.json", optional: false);
    })

If you use the docs, this results in:

Unhandled exception. System.IO.FileNotFoundException: The configuration file 'appsettings.Staging.json' was not found and is not optional. The expected physical path was '/azure-functions-host/appsettings.Staging.json'.

[ac931274]

Re getting over the lack of INameResolver, take a look at my post on Stack Overflow about how I resolved my issue. https://stackoverflow.com/questions/78897966/azure-functions-trigger-variables-isolated-functions/78897967