How to see request body in Application Insights

Question

I have an HTTP function that is periodically failing with status of 0 with the following error:

Exception while executing function: {function-name} Exception binding parameter 'req' Unexpected end of request content.

I'm trying to debug using Application Insights. Specifically, I want to inspect the request body to understand why it might be failing. I found an older answer that seems to answer it here, suggesting the following query:

requests
| where success == true>
| where httpMethod == "POST">
| project timestamp, url, requestBody

When I try to run this query, I can see that httpMethod and requestBody are not columns of request. Appreciate any help, thanks.

Answer 1

@Brandon DeMatteis - Welcome to Microsoft Q&A and thanks for reaching out to us. UPDATE: Apologies for the delay in responding to you.

Azure Monitor Application Insights provides powerful tools for monitoring and troubleshooting applications, but it does not log request bodies by default due to privacy and performance considerations.

1. You can try to enable logging of Request Bodies. Ensure that your application is configured to log request bodies, which might involve custom logging that captures the request body and logs it.
2. For Azure Functions: - Use the context.log method to log the request body. - Be mindful of privacy and data regulations (like GDPR) when logging sensitive information.
3. Integrate with Application Insights: If not already set up, ensure that your Azure Function is integrated with Application Insights. This is usually straightforward: - In the Azure Portal, navigate to your Function App settings. - Find the Application Insights section and link it to an AI resource.
4. Log Custom Telemetry: After ensuring that request bodies can be captured in your function code, you can send this data as custom telemetry to Application Insights. This involves using the Application Insights SDK to create custom events or traces.

public static async Task<IActionResult> Run(HttpRequest req, ILogger log, ExecutionContext context)
{
    string requestBody = await new StreamReader(req.Body).ReadToEndAsync();
    // Log the request body or parts of it as custom telemetry
    var telemetry = new TelemetryClient();
    telemetry.TrackTrace($"Request body: {requestBody}");
 
    // Your function logic here
 
    return new OkResult();
}

   5. Once you've started logging the request bodies or relevant parts as custom telemetry, you can query this data in Application Insights: - Navigate to your Application Insights resource in the Azure Portal. - Go to the "Logs" section. - Use the Kusto Query Language (KQL) to query custom logs. 

6. Analyze the Data: With the logged request bodies available in Application Insights, you can start analyzing the patterns or specific request contents that might be leading to the failures. 

 

Hope this helps. and please feel free to reach out if you have any further questions.  
 

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