Adding middleware or alike in Azure functions v2

Question

I need to add correlationId to my logging context and I did it on my MVC project by adding CorrelationId nuget to the project and setting up its middleware, but I could not do the same in Azure functions.

I have loaded the ICorrelationContextAccessor using Dependency injection and then set my correlationId like this:

    [FunctionName("func1")]
    public async Task Run([ServiceBusTrigger("mytopic", "MySubscription", Connection = "ServiceBusConnectionString")]Message message)
    {
        _correlationContextAccessor.CorrelationContext = _correlationContextFactory.Create(message.CorrelationId, "X-Correlation-ID");
        _logger.LogInformation($"C# ServiceBus topic trigger function processed message: {message.MessageId}, {Encoding.UTF8.GetString(message.Body)}");

It works fine and I see my correlationId in the log line below and in my services in the function. The only part that I am missing is that I have logs regarding the start and finish of the function that still has no correlationId, which kind of make sense becaue when the function wants to log that it has received the message the correlationId is not set.

Answer 1

The short version is that you can't effect the logging code that runs before your function using the built in bindings.

You won't be able to change that first "C# Timer trigger function processed message" as the message hasn't been read at that point-- it would be the same as trying to get the correlation ID set in your MVC project before reading the incoming HTTP request.

You could add logging as soon as the message is first received by creating a custom binding . I would encourage you to consider carefully whether or not it is worth building and maintaining a custom binding to get your logging setup a few lines sooner.