Suppress the connection warning message when using Managed Identity

[shibayan]

When using Managed Identity in Binding / Trigger, you need to specify a nested value prefixed with the connection name. (Example: <CONNECTION_NAME_PREFIX>__serviceUri)

https://docs.microsoft.com/en-us/azure/azure-functions/functions-reference#connection-properties

Function Build SDK does not take nested values into account, so even if you add the correct settings to local.settings.json, it will warn you that the connection cannot be found, which is an unnecessary warning.

Build warning

C:\Users\shibayan\.nuget\packages\microsoft.net.sdk.functions\3.0.13\build\Microsoft.NET.Sdk.Functions.Build.targets(32,5): 
warning : Function [Function2]: cannot find value named 'CosmosConnection' in local.settings.json that matches 'connection' property set on 'cosmosDBTrigger'

Repro code

{
  "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "UseDevelopmentStorage=true",
    "FUNCTIONS_WORKER_RUNTIME": "dotnet",
    "CosmosConnection__accountEndpoint": "https://***.documents.azure.com:443/"
  }
}

public class Function2
{
    [FunctionName("Function2")]
    public void Run([CosmosDBTrigger(
                        databaseName: "SampleDB",
                        containerName: "TodoItem",
                        Connection = "CosmosConnection",
                        LeaseContainerName = "leases")]
                    IReadOnlyList<TodoItem> items, ILogger log)
    {
        if (items != null && items.Count > 0)
        {
            log.LogInformation("Documents modified " + items.Count);
            log.LogInformation($"First document Id = {items[0].Id}, Title = {items[0].Title}");
        }
    }
}

[mattchenderson]

This looks like it comes from:

azure-functions-vs-build-sdk/src/Microsoft.NET.Sdk.Functions.Generator/FunctionJsonConverter.cs

Line 261 in b0e54a8

_logger.LogWarning($"Function [{functionName}]: cannot find value named '{appSettingName}' in {settingsFileName} that matches '{token.Key}' property set on '{binding["type"]?.ToString()}'");

Related changes had to be made to the Core Tools, although those could force the process to exit, while this seems to just be warning level. This should still be fixed. Core Tools PRs for reference in case it's useful in resolution:

• Support secretless extensions  azure-functions-core-tools#2652
• Prevent warnings with identity-based connections azure-functions-core-tools#2768

[huytranbandlab]

Hello, this issue still happens on version 4.1.3

[akimotochan]

@mattchenderson still happening at 4.3.0 :(

Any guidance?