NamedValue not getting replaced in Connection String for APIM Bicep

[sajid08]

Bicep version
v0.31.92

Describe the bug
I have a namedValue defined for APIM that in turn refers it's value from a key vault secret, but when I try to use that namedValue in the connection string for Application Insights logger, it fails with this error.

"Validation failed for logger-id 'appi_logger_smi'. Exception Received 'Invalid instrumentation key for Application Insights Logger"

To Reproduce
Define a NamedValue like this

resource apim_name_appi_instrumentation_key 'Microsoft.ApiManagement/service/namedValues@2023-05-01-preview' = {
  parent: apim_name_resource
  name: 'appi-instrumentation-key'
  properties: {
    displayName: 'appi-instrumentation-key'
    keyVault: {
      secretIdentifier: 'https://${kv_name}.vault.azure.net/secrets/appi-instrumentation-key'
    }
    tags: []
    secret: true
  }
}

then try to access it in the logger.

resource aiLoggerWithSystemAssignedIdentity 'Microsoft.ApiManagement/service/loggers@2022-08-01' = {
  name: 'appi_logger_smi'
  parent: apim_name_resource
  properties: {
    loggerType: 'applicationInsights'
    description: 'Application Insights logger with system-assigned managed identity'
    credentials: {
      connectionString: 'InstrumentationKey=@{{appi-instrumentation-key}};IngestionEndpoint=https://uksouth-1.in.applicationinsights.azure.com/'
      identityClientId: 'systemAssigned'
    }
    isBuffered: true
    resourceId: appi_externalid
  }
  dependsOn: [
    apim_name_appi_instrumentation_key
  ]
}

Additional context
Add any other context about the problem here.

[levimatheri]

I think it might be due to how the named-value is referenced. Try removing the @, i.e. connectionString: 'InstrumentationKey={{appi-instrumentation-key}};IngestionEndpoint=https://uksouth-1.in.applicationinsights.azure.com/'

[sajid08]

I think it might be due to how the named-value is referenced. Try removing the @, i.e. connectionString: 'InstrumentationKey={{appi-instrumentation-key}};IngestionEndpoint=https://uksouth-1.in.applicationinsights.azure.com/'

Yes, I tried that first, it fails with validation error

[miqm]

I think you can't use connection string with api-management. I think it only supports instrumentationKey like this:

resource applicationInsightsLogger 'Microsoft.ApiManagement/service/loggers@2020-12-01' = {
  parent: apiManagement
  name: applicationInsightsName
  properties: {
    loggerType: 'applicationInsights'
    credentials: {
      instrumentationKey: '{{${applicationInsightsNamedValue.properties.displayName}}}'
    }
  }
}

I'm using this widely and it works like a charm the named value can be a KV reference, it doesn't really matter as the API-M fetches the value into it's store and then it's used in policies or in above.