Replace TraceWriter With ILogger in azure function V2

Question

We are trying to migrate azure function to sdk.functions 1.0.21 and we upgraded everything to 3.0.0-rc1 . The console prompted us that the TraceWriter is obsolete and to use ILogger instead. However, we keep running into issues.

Here's the code that I'm using:

code.cs:

public static async Task Run(Message queueItem, ILogger log, ExecutionContext context){
  using (var scope = Resolver.CreateScope())
  {
    var timer = new Stopwatch();

    try
    {
      var resolver = scope.ServiceProvider;

      logger = resolver.GetService<IBestLogger>().WithInvocationId(context);
      client = resolver.GetService<IServiceBusFactory>().GetClient(logger, _queue, _failedQueue);
      auditRepository = resolver.GetService<ITplTransactionAuditRepository>();

      asnService = resolver.GetService<IAsnService>();
      var sfWmsService = resolver.GetService<ISnapfulfilWmsService>();

      logger.CreateContext($"{_queue} process is started for message id.").WithServiceBusMessage(queueItem).LogInformation();
    }
  }

  catch (Exception ex2)
  {
    errorMessage = $"Unable to set record to Error status for message id {queueItem.MessageId} in {_queue}.";
    if (logger == null)
      log.Error(errorMessage);
    else
      logger.CreateContext(errorMessage, ex2).LogError();
  }
}

function.json:

{
  "bindings": [
    {
      "queueName": "%InvoiceDetailCalculate_Queue%",
      "connection": "ServiceBus_Connection",
      "name": "queueItem",
      "type": "serviceBusTrigger",
      "direction": "in",
      "accessRights": "manage"
    }
  ],
  "disabled": false
}

Run.csx:

#r "../bin/Best.Billing.Functions.dll"
#r "../bin/Best.Libraries.Utility.dll"

public static async void Run(Message queueItem, ILogger log, ExecutionContext context)
{
    try
    {
        Code.Run(queueItem, log, context).Wait();
    }
    catch (Exception ex)
    {        
        ex.Rethrow();
    }
}

The error messages are:

Run.csx(4,26): warning AF008: This method has the async keyword but it returns void
Run.csx(4,30): error CS0246: The type or namespace name 'Message' could not be found (are you missing a using directive or an assembly reference?)
Run.csx(8,9): error CS0103: The name 'Code' does not exist in the current context
Run.csx(12,13): error CS1061: 'ILogger' does not contain a definition for 'Error' and no extension method 'Error' accepting a first argument of type 'ILogger' could be found (are you missing a using directive or an assembly reference?)
Run.csx(13,12): error CS1061: 'Exception' does not contain a definition for 'Rethrow' and no extension method 'Rethrow' accepting a first argument of type 'Exception' could be found (are you missing a using directive or an assembly reference?)
Run.csx(4,26): warning CS1998: This async method lacks 'await' operators and will run synchronously. Consider using the 'await' operator to await non-blocking API calls, or 'await Task.Run(...)' to do CPU-bound work on a background thread.
Function compilation error

Answer 1

You need to do two things:

1. First, add a reference to the Ilogger.

   At the top of the function, add a using Microsoft.Extensions.Logging; statement.

2. Second, you'll need to use the Ilogger method names. Change log.Error(errorMessage) to log.LogError(errorMessage). You'll need to do this everywhere you were calling the TraceWriter methods.

Here's a full list of the newer ILogger methods.

As an example, below is a fully implemented Azure Function v2 .NET Standard using Ilogger instead of Tracewriter:

using System.IO;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.AspNetCore.Http;
using Microsoft.Azure.WebJobs.Host;
using Newtonsoft.Json;
using Microsoft.Extensions.Logging;

namespace FunctionApp1
{
    public static class Function1
    {
        [FunctionName("Function1")]
        public static IActionResult Run(
            [HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)]HttpRequest req,
            ILogger log)
        {
            log.LogInformation("C# HTTP trigger function processed a request.");


            string name = req.Query["name"];

            string requestBody = new StreamReader(req.Body).ReadToEnd();
            dynamic data = JsonConvert.DeserializeObject(requestBody);
            name = name ?? data?.name;

            return name != null
                ? (ActionResult)new OkObjectResult($"Hello, {name}")
                : new BadRequestObjectResult("Please pass a name on the query string or in the request body");
        }
    }
}