Value cannot be null. (Parameter 'connectionString') in DiagnosticEventTableStorageRepository using system assigned managed identity

[DavidVollmers]

Investigative information

Please provide the following:

• Timestamp: 2024-12-04T15:27:38.8719369Z
• Function App version: 4.1036.2.2 (Host version)
• Function App name: role-functions-staging-ca
• Function name(s) (as appropriate): -
• Invocation ID: -
• Region: West Europe

Repro steps

1. Setup new function app on container app using system assigned managed identity
2. Set AzureWebJobsStorage__accountName as described in here
3. Deploy container image

Expected behavior

The class DiagnosticEventTableStorageRepository should work in combination with system assigned managed identities.

Actual behavior

The container app fails to start with the following error:

The Azure Storage connection string is either empty or invalid. Unable to record diagnostic events, so the diagnostic logging service is being stopped.

Value cannot be null. (Parameter 'connectionString') at Azure.Data.Tables.TableServiceClient..ctor(String connectionString,TableClientOptions options) at Microsoft.Azure.WebJobs.Script.WebHost.Diagnostics.DiagnosticEventTableStorageRepository.get_TableClient() at /src/azure-functions-host/src/WebJobs.Script.WebHost/Diagnostics/DiagnosticEventTableStorageRepository.cs : 69

Related information

Using mcr.microsoft.com/azure-functions/dotnet-isolated:4-dotnet-isolated8.0 as a base image.

Package and Framework references:

<FrameworkReference Include="Microsoft.AspNetCore.App"/>
<PackageReference Include="Microsoft.Azure.Functions.Worker" Version="1.23.0"/>
<PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Http" Version="3.2.0"/>
<PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore" Version="1.3.2"/>
<PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Storage.Queues" Version="5.5.0"/>
<PackageReference Include="Microsoft.Azure.Functions.Worker.Sdk" Version="1.18.1"/>
<PackageReference Include="Microsoft.ApplicationInsights.WorkerService" Version="2.22.0"/>
<PackageReference Include="Microsoft.Azure.Functions.Worker.ApplicationInsights" Version="1.4.0"/>

[Red1971]

I am having a similar issue with my Azure Function App. I am using a 'user-assigned-identity' (UAI) to access the 'working storage account' (WSA).

The UAI has been granted RBAC perms on the WSA...

"Storage Blob Data Contributor", "Storage Queue Data Contributor", "Storage Account Contributor", "Storage Blob Data Owner", "Storage Table Data Contributor"

[cjaliaga]

Hey @DavidVollmers , thank you for providing the detailed information.

Support for identity-based connections will be included in the next release (PR: #10438). That said, this issue shouldn't cause the function app to fail to start. Are you observing a start failure, or is this just being logged during initialization?

[DavidVollmers]

The function app fails to start, but I found out that this actually happens because of some custom startup logic.