NLog: NLog in Azure Function - not working when resolved with DI

Hi,

I’ve been struggling for a while now, to use NLog in an Azure function. I got to the point where:

1. I have a Startup class in my function where I configure and register NLog to the ServiceCollection, through the loggingBuilder , using an ElasticSearch target

2. The ILogger instance that is passed to the RUN method of the function works (i.e. I see my logs in Elastic Search)

3. Further in my function I resolve a custom application service using the IServiceProvider , in the application service I have an ILogger<T> as a dependency. This is also resolved fine, and among the _loggers property I can see an instance of NLogger. But when calling the logger.LogError method, nothing happens, no exception, and I don’t see anything in ElasticSearch

My Startup.cs:

public class Startup : FunctionsStartup
    {
        public Startup()
        {
            // LogManager.Configuration = new XmlLoggingConfiguration("NLog.config");
            // NLogBuilder.ConfigureNLog(LogManager.Configuration);
            LoggingConfiguration config = new LoggingConfiguration();
            LogManager.ThrowExceptions = true;
            var elasticTarget = new ElasticSearchTarget()
            {
                Uri = "----the url -----",
                IncludeAllProperties = true,
                Fields = new List<Field>()
                {
                    new Field()
                    {
                        Name = "host",
                        Layout = "${aspnet-request-host}"
                    },
                    new Field()
                    {
                        Name = "machine",
                        Layout = "${machinename}"
                    },
                    new Field()
                    {
                        Name = "activityid",
                        Layout = "${aspnet-TraceIdentifier}"
                    }
                }
            };

            var bufferedElasticTarget = new BufferingTargetWrapper("ElasticSearch", elasticTarget)
            {
                FlushTimeout = 10000
            };

            config.AddTarget(bufferedElasticTarget);

            var nlogElasitcSearchRule = new LoggingRule("*", NLog.LogLevel.Debug, elasticTarget);
            config.LoggingRules.Add(nlogElasitcSearchRule);

            NLogBuilder.ConfigureNLog(config);
            LogManager.Configuration = config;
        }

        public override void Configure(IFunctionsHostBuilder builder)
        {
            try
            {
                var config = builder.Services.BuildServiceProvider().GetRequiredService(typeof(IConfiguration)) as IConfiguration;
                var originationConfiguration = new OriginationConfiguration();
                config.GetSection("OriginationConfigs").Bind(originationConfiguration);
                builder.Services.AddOriginationServices(originationConfiguration);

                builder.Services.AddLogging((loggingBuilder) => { loggingBuilder.AddNLog(); });
            }
            catch (Exception ex)
            {
                var abc = ex;
            }
        }
    }

My function:

 [FunctionName(nameof(PingHttpTrigger))]
        public IActionResult PingHttpTrigger(
            [HttpTrigger(AuthorizationLevel.Anonymous, "get", Route = "ping")] HttpRequest req, ILogger log)
        {
            try
            {
                throw new Exception("cocomarla_exceptie");
            }
            catch (Exception ex)
            {
                // this logging works, no problem
                log.LogError(ex, "error test");
            }

            CustomerRegisteredEvent customerRegistered = new CustomerRegisteredEvent()
            {
                AggregateId = Guid.NewGuid(),
                EventId = Guid.NewGuid(),
                Customer = new Context.Entities.Customer()
            };

            var customerEventHandler = _serviceProvider.GetRequiredService<IEventHandler<CustomerRegisteredEvent>>() as IEventHandler<CustomerRegisteredEvent>;

            customerEventHandler.Handle(customerRegistered);

            return new OkObjectResult(new { timestamp = DateTime.UtcNow });
        }

And the CustomerEventHandler class:

 public class CustomerEventHandler : IEventHandler<CustomerRegisteredEvent>,
                                        IEventHandler<CustomerUpdatedEvent>
    {
        private ICustomerService customerService;
        private ILogger<CustomerEventHandler> logger;

        public CustomerEventHandler(ICustomerService customerService, ILogger<CustomerEventHandler> logger)
        {
            this.customerService = customerService;
            this.logger = logger;
        }

        public void Handle(CustomerRegisteredEvent @event)
        {
            try
            {
                throw new Exception("cocomarla_exceptie");
            }
            catch (Exception ex)
            {
                // this doesn't work, no log anywhere
                logger.LogError(ex, "error test");
            }

            // customerService.CreateCustomerProjection(@event.Customer);
        }

        public void Handle(CustomerUpdatedEvent @event)
        {
            customerService.UpdateCustomerProjection(@event.Customer);
        }
    }

I think there must be a conflict somewhere, because the Azure Function’s pipeline must be slightly different than the ASP.NET pipeline, so probably something doesn’t add up in the ServiceCollection… not sure.

Thoughts ? Any help would be greatly appreciated.

Thanks, Vlad