Viewing real-time application logs

Perform the following steps:

1. Navigate to Platform features of the function app and click on the Log Streaming button, where you can view the Application logs , as shown in the following screenshot:

At the time of writing, web server logs provide no information relating to Azure Functions. 

2. Let's open any of the Azure Functions that you added earlier in a new browser tab and add a line of code that causes an exception. To make it simple (and to just illustrate how application logs in log streaming work), I have added the following line to the simple HTTP trigger that I created earlier:

3. Subsequently, click on the Save button and then on the Run button. As expected, you will receive an exception, along with the message in the Application logs section shown in the following screenshot:

The log window shows errors only for that particular function, and not for the other functions associated with the function app. That is where log streaming application logs come in handy, which can be used across the functions of any given function app.