CODEWITHSUNDEEP
azuredependency-injectionazure-functions
user10101
user10101

Reputation: 1764

Use a stub when running Azure Functions locally

I have an Azure Functions (.NET Core) project and I would like to select an implementation for some class depending on the environment. Something like the following:

public class Startup : FunctionsStartup
{
    public override void Configure(IFunctionsHostBuilder builder)
    {
        builder.Services.AddLogging();
        #if azure environment
        builder.Services.AddSingleton<IAzureApi, AzureApi>();
        #else
        builder.Services.AddSingleton<IAzureApi, AzureApiStub>();
        #endif
    }
}

What would be the best way to do this? Is it possible to configure such behavior local.settings.json?

Upvotes: 0

Views: 193

Answers (2)

Chris
Chris

Reputation: 3293

You could use the DEBUG preprocessor directive in your Startup.cs file:

public class Startup : FunctionsStartup
{
    public override void Configure(IFunctionsHostBuilder builder)
    {
#if DEBUG
        builder.Services.AddSingleton<IAzureApi, AzureApiStub>();
#else
        builder.Services.AddSingleton<IAzureApi, AzureApi>();
#endif
    }
}

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/preprocessor-directives/preprocessor-if

You have to be running your solution in Debug configuration which I assume you would be doing when running locally?

Upvotes: 1

Manish
Manish

Reputation: 1182

Easy way to achieve this by using custom property in the config file. 

 [FunctionName("CustomSettings")]
public static Task<HttpResponseMessage> Run([HttpTrigger(AuthorizationLevel.Anonymous, "GET")]HttpRequestMessage req, TraceWriter log)
{
    var customSetting =  Environment.GetEnvironmentVariable("AzureEnvironment", EnvironmentVariableTarget.Process);
    if(customSetting == "Development")
    {
        //dosomething
    }
}

Add this property in the azure portal manually (AppSettings).
for more info -> https://learn.microsoft.com/en-us/sandbox/functions-recipes/environment-variables?tabs=csharp
https://learn.microsoft.com/en-us/azure/azure-functions/functions-dotnet-class-library#environment-variables

Upvotes: 1

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