Troubleshooting Performance Problems related to Application Domains reloading
Throughout my time working on the IIS team I've seen a lot of cases where frequent unloading of the Application Domains caused several performance issues. While there are a lot of blog post covering the mechanism ASP.NET uses to detect changes in the files, each of them only covers one aspect of the problem. Hopefully this article can provide a more unified perspective and help you understand how you can troubleshoot or prevent these issues.Fetching Windows Auth User ID Issue in Python Flask Application on IIS with HttpPlatformHandler
Problem : Deploying Python Flask applications on IIS can be a smooth process, but occasionally, issues arise that require careful troubleshooting. One such issue involves the failure of a Flask application to retrieve the Windows Authentication user ID when using the HttpPlatformHandler. Please note that retrieving the user details was successful using WFastCGI but not with HttpPlatformHandler. Let’s see how we can fetch the user details in such scenario. Few Pointers : Move to HttpPlateFormHandlers form WFastCGI: WFastCGI is no longer maintained. Refer to this. Configure Python web apps for IIS - Visual Studio (Windows) | Microsoft Learn Configuration Adjustment: A key step was enabling the ForwardWindowsAuthToken option in the HttpPlatformHandler configuration. This setting forwards the Windows Authentication token to the application, allowing it to be accessed and processed within the code. Code Implementation: After adjusting the configuration, you can update the Flask application code to fetch the Windows Authentication user ID. The following code snippet demonstrates how this was done: from flask import Flask, request, render_template import os import win32api import win32security def create_app(): app = Flask(__name__) @app.route("/") def hello_world(): s_vars = request.environ user = os.environ.get('USERNAME') handle_str = request.headers['x-iis-windowsauthtoken'] handle = int(handle_str,16) win32security.ImpersonateLoggedOnUser(handle) user1 = win32api.GetUserName() win32api.CloseHandle(handle) return f"Hello World!: {user1}" return app This code snippet demonstrates how to use the win32api and win32security modules to impersonate the logged-on user and retrieve their username. The important element here is the x-iis-windowsauthtoken header, which contains the Windows Authentication token passed on by the HttpPlatformHandler. Ensure Dependencies: Please ensure that the pywin32 package is installed, as it provides the necessary functionality to interact with Windows APIs within the Python environment. For further information, refer to the following resources: Configure Web Apps for IIS in Python HttpPlatformHandler Configuration ReferenceHigh CPU Consumption in IIS Worker Processes
Struggling with high CPU usage in your IIS worker processes? Discover how to identify and troubleshoot these issues effectively. From recognizing symptoms to collecting crucial data using tools like Perfview and Procdump, our comprehensive guide will help you optimize your web application’s performance. Dive in to learn more and keep your server running smoothly!Configuring CORS in IIS with the IIS CORS Module: A Step-by-Step Guide
The Cross-Origin Resource Sharing (CORS) is a security feature implemented by web browsers that enables control of which resources are accessible based on the origin of requests. This way, web servers are given the authority to define which domains are allowed to access resources, ensuring only trusted sources will interact with your server. In this modern era of applications, where most web apps fetch data from multiple origins, CORS is very important to manage and secure these interactions.HTTP 500 Internal Server Errors: Understanding and Log Collection for Effective Analysis
The HTTP 500 Internal Server Error is one of the most common errors faced by developers and administrators when hosting web applications in IIS. This error indicates that the server encountered an issue preventing it completing the request, but it doesn’t provide much detail on what went wrong. To effectively troubleshoot the problem understanding of 500 status code and detailed log collection are essential. In this article, we’ll explore the 500 Internal Server Error, why it happens, and the various methods for collecting useful diagnostic logs.How to fix Failed to Load API Definition error in SwaggerUI when hosting an ASP.NET Core API in IIS
When hosting an ASP.NET Core API, it’s not uncommon to encounter the "Failed to load API definition" error in SwaggerUI. This article will explore the reasons behind this error and provide steps to resolve it.Application Pool Does Not Recycle at Defined Conditions
Have you ever wondered why the Application Pool sometimes fails to recycle according to the specified conditions, such as regular time intervals or specific schedules? There can be various reasons behind this unexpected behavior. In this article, we will explore the most common causes of this issue.CPU Management in IIS Application Pools: A Deep Dive into Advanced Settings for Optimal Performance
Application pools provide an isolation between different web application in Internet Information Services (IIS) by allowing you to manage the resources, recycling, and performance per application. Control of CPU usage is going to be one of the most critical factors in the performance and management of an application pool. IIS includes a dedicated section under ApplicationPool -> Advance Settings for the management of CPU. it provides varied settings that enable you to optimize the utilization of the CPU so that a particular server resource does not become dominated by one application. This article will dive into the CPU settings for an ApplicationPool, explaining each option and its configuration.How to Configure and Collect Schannel and CAPI2 Logs
CAPI2 log is a diagnostic log in Windows that tracks cryptographic operations. It track events related to certificate validation, key exchange. It also record how Windows and applications use cryptographic algorithms for securing data. This is crucial for diagnosing issues with SSL/TLS, digital signatures, and other encryption-related processes. CAPI2 logs are particularly useful for diagnose security-related problems in Windows systems. When troubleshooting issues related to cryptographic operations in Windows, it may be necessary to enable and collect logs for both Schannel and CAPI2. This article will help you to configure and collect these logs for diagnostic purposes.
