Azure Functions : How to write a custom logs in Application Insights

Introduction

In this blog, we will see how to write a custom trace logs and exception in Application Insights using Azure Function/Console App(Web Job).

If you are looking for a way to configure Application Insights for Azure Function then please refer below link.

https://docs.microsoft.com/en-us/azure/azure-functions/functions-monitoring

Problem Statement

We have a requirement, In which Azure function will connect to the third-party application after a specific time interval and retrieved the failed jobs. We want to logs those exceptions in Application Insights.

Prerequisites

Access to Azure account – Admin or Co-Admin role.
Visual Studio 2017 or above.

Note: Application Insights will capture the logs for the Apps(Any Custom C# Code) running in Azure Environment. It will not capture the logs from the application running on your local machine.
The Same code is applicable for console app running in Azure Environment as a Web Job.

Modules

Provision Application Insights
Create a Azure Function in Visual Studio
Provision a Azure Function in Azure Portal
Publish the App from Visual Studio
Execute the Azure Function from Postman.
Verify the Logs using Logs(Analytics)

Let’s focus on the first part and provision the Azure service.

1. Provision Application Insights

Steps :

2. Open the resource group and click on + Add.

Search for Application Insights and Select the resource.

Kindly wait for the deployment process.

Copy the Instrument Key. We will require this key within our code.

2. Create a Azure Function

Steps :

Create a new Azure Function

2. Add NuGet Packages Microsoft.ApplicationInsights

Please download the Code from GitHub

using Microsoft.ApplicationInsights;
using Microsoft.ApplicationInsights.DataContracts;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.Azure.WebJobs.Host;
using System;
using System.Collections.Generic;
using System.Net;
using System.Net.Http;
using System.Threading.Tasks;

namespace WriteCustomLogsToApplicationInsights
{
    public static class CustomLogs
    {
        [FunctionName("CustomLogs")]
        public static async Task<HttpResponseMessage> Run([HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)]HttpRequestMessage req, TraceWriter log)
        {
            log.Info("C# HTTP trigger function processed a request.");

            TelemetryClient telemetry = new TelemetryClient();
            telemetry.InstrumentationKey = "384a6401-3bed-400c-8e36-e248f397c3bb";


            ///--------------------------------------***Trace Log Simple Information***----------------------------------------------//
           log.Info("Writing TrackTrace with SeverityLevel - Information.");
            telemetry.TrackTrace("This is a Custom Trace Log.", SeverityLevel.Information);
            ///---------------------------------------******-------------------------------------------------------------------------//


            ///--------------------------------------***Trace Log Simple Warning***----------------------------------------------//
           log.Info("Writing TrackTrace with SeverityLevel - Warning.");
            telemetry.TrackTrace("This is a Custom Trace Log.", SeverityLevel.Warning);
            ///---------------------------------------******-------------------------------------------------------------------------//


            ///--------------------------------------***Trace Log With Extra Properties***----------------------------------------------//
           log.Info("Writing TrackTrace with custom properties.");
            telemetry.TrackTrace("This is a Custom Trace Log.", SeverityLevel.Information, new Dictionary<string, string> { { "databaseid", new Guid().ToString()} });
            ///---------------------------------------******-------------------------------------------------------------------------//


            ///--------------------------------------***Exception Log***-------------------------------------------------------------//
           log.Info("Writing TrackException.");
            Exception exception = new Exception("This is a custom Exception.");
            telemetry.TrackException(exception);
            ///---------------------------------------******-------------------------------------------------------------------------//


            ///---------------------------------------***Flushing***-------------------------------------------//
           log.Info("Flushing..");
            telemetry.Flush();
            // Allow some time for flushing before shutdown.
            System.Threading.Thread.Sleep(5000);
            ///---------------------------------------******-------------------------------------------//
            log.Info("Completed.");

            return req.CreateResponse(HttpStatusCode.OK, "Success ");
        }
    }
}