Add prerequisites sections to Azure App Service docs

Add Prerequisites sections to all three Azure App Service deployment
variants (Windows Code, Linux Code, Linux Container) to help users
understand requirements and platform-specific differences before setup.

Key additions:
- Prerequisites sections explaining deployment model differences
- Cross-references between the three App Service variants
- Enhanced .NET sections with links to APM and configuration docs
- Configuration sections with platform-specific notes
- Additional Resources sections with troubleshooting links

Windows Code:
- Warning about not installing MSI on App Service
- Links to Azure Functions and Linux variants

Linux Code:
- Enhanced .NET section with environment variable guidance
- Additional Resources section with APM cross-references

Linux Container:
- Prerequisites explaining sidecar vs other approaches
- Configuration section with container-specific notes
- Additional Resources with custom instrumentation links

This improves navigation and helps users understand how each Azure
App Service deployment model differs from standard APM setup.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: lucaspimentel

content/en/serverless/azure_app_service/linux_code.md

@@ -15,6 +15,18 @@ If you would prefer to not use the sidecar approach (Not Recommended), you can i
 
 **Supported runtimes**: Java, Node.js, .NET, PHP, Python
 
+## Prerequisites
+
+1. **Install the Azure integration:** Install the [Datadog-Azure integration](/integrations/azure/) to collect Azure metrics and logs.
+2. **Understand the sidecar approach:** This setup uses a sidecar container pattern, which differs from:
+   - [Windows Code deployment](/serverless/azure_app_service/windows_code) (uses extension)
+   - [Standard .NET APM setup](/tracing/trace_collection/automatic_instrumentation/dd_libraries/dotnet-core) (uses Agent or NuGet)
+3. **Review .NET compatibility:** See [.NET Core Compatibility](/tracing/trace_collection/compatibility/dotnet-core) for supported runtimes and integrations.
+
+<div class="alert alert-info">
+Using Windows instead? See <a href="/serverless/azure_app_service/windows_code">Windows Code setup</a>. Using containers? See <a href="/serverless/azure_app_service/linux_container">Linux Container setup</a>.
+</div>
+
 ## Setup
 
 ### Azure integration
@@ -54,14 +66,18 @@ Instrumentation starts when the application is launched.
 {{% /tab %}}
 {{% tab ".NET" %}}
 
-Add the `Datadog.Trace.Bundle` Nuget package to your project. See [the Nuget package page for more details][102].
+Add the `Datadog.Trace.Bundle` Nuget package to your project. See [the Nuget package page for more details][102] or [Tracing .NET Core Applications](/tracing/trace_collection/automatic_instrumentation/dd_libraries/dotnet-core) for background.
 
 For example:
 
 ```shell
 dotnet add package Datadog.Trace.Bundle --version 3.21.0
 ```
 
+**Important:** The environment variables shown in the [.NET: Additional required environment variables](#dotnet-additional-settings) section are critical for .NET to work with the sidecar pattern.
+
+For more on these environment variables, see [Library Configuration](/tracing/trace_collection/library_config/dotnet-core/).
+
 [102]: https://www.nuget.org/packages/Datadog.Trace.Bundle#readme-body-tab
 
 {{% /tab %}}
@@ -340,6 +356,13 @@ Be sure to enable **App Service logs** to receive debugging logs.
 
 Share the content of the **Log stream** with [Datadog Support][9].
 
+## Additional Resources
+
+- [Tracing .NET Core Applications](/tracing/trace_collection/automatic_instrumentation/dd_libraries/dotnet-core) - Core APM concepts
+- [.NET Core Library Configuration](/tracing/trace_collection/library_config/dotnet-core/) - Full configuration reference
+- [.NET Custom Instrumentation](/tracing/trace_collection/custom_instrumentation/dotnet/) - Adding custom spans
+- [Connecting .NET Logs and Traces](/tracing/other_telemetry/connect_logs_and_traces/dotnet) - Log correlation
+
 ## Further reading
 
 {{< partial name="whats-next/whats-next.html" >}}

content/en/serverless/azure_app_service/linux_container.md

@@ -21,6 +21,15 @@ This document assumes that your application is set up for sidecars according to
 
 If you would prefer to not use the sidecar approach (Not Recommended), you can instead follow the instructions to [Instrument Azure App Service - Linux Container with `serverless-init`][2].
 
+## Prerequisites
+
+1. **Install the Azure integration:** Install the [Datadog-Azure integration](/integrations/azure/) to collect Azure metrics and logs.
+2. **Understand container instrumentation:** This guide instruments a containerized app with a sidecar. For other deployment models, see:
+   - [Windows Code](/serverless/azure_app_service/windows_code) - Extension-based
+   - [Linux Code](/serverless/azure_app_service/linux_code) - Sidecar for non-containerized apps
+3. **Review container setup basics:** If you're new to Datadog's .NET tracer in containers, see [Tracing .NET Core Applications](/tracing/trace_collection/automatic_instrumentation/dd_libraries/dotnet-core) for background.
+4. **Check compatibility:** See [.NET Core Compatibility](/tracing/trace_collection/compatibility/dotnet-core) for supported runtimes.
+
 ## Setup
 
 ### Azure integration
@@ -576,6 +585,21 @@ $statsd->increment('page.views', 1, array('environment'=>'dev'));
 {{% /tab %}}
 {{< /tabs >}}
 
+## Configuration
+
+The .NET tracer supports configuration via environment variables. See [.NET Core Library Configuration](/tracing/trace_collection/library_config/dotnet-core/) for all available options.
+
+**Container-specific notes:**
+- Environment variables are set in your Azure App Service Application Settings
+- The sidecar handles Agent connectivity automatically
+- Logs should be written to `/home/LogFiles/` for collection
+
+## Additional Resources
+
+- [.NET Custom Instrumentation](/tracing/trace_collection/custom_instrumentation/dotnet/) - Adding custom spans
+- [.NET Diagnostic Tool](/tracing/troubleshooting/dotnet_diagnostic_tool) - Troubleshooting
+- [Connecting .NET Logs and Traces](/tracing/other_telemetry/connect_logs_and_traces/dotnet) - Log correlation
+
 [1]: https://learn.microsoft.com/en-us/azure/app-service/tutorial-custom-container-sidecar
 [2]: /serverless/guide/azure_app_service_linux_containers_serverless_init
 [3]: https://app.datadoghq.com/integrations/azure

content/en/serverless/azure_app_service/windows_code.md

@@ -62,6 +62,23 @@ There are no billing implications for tracing Java Web Apps during this period.
 {{% /tab %}}
 {{< /tabs >}}
 
+## Prerequisites
+
+1. **Install the Azure integration:** Install the [Datadog-Azure integration](/integrations/azure/) first to correlate APM traces with Azure metrics.
+2. **Understand the extension approach:** The Azure App Service extension is a specialized version of the Datadog .NET tracer. It differs from standard APM setup:
+   - No MSI installer needed (extension handles installation)
+   - No manual environment variable configuration for basic setup
+   - Automatic integration with IIS
+3. **Review .NET compatibility:** See [.NET Core Compatibility](/tracing/trace_collection/compatibility/dotnet-core) or [.NET Framework Compatibility](/tracing/trace_collection/compatibility/dotnet-framework) for supported versions.
+
+<div class="alert alert-warning">
+<strong>Do not install the Datadog .NET tracer MSI</strong> on Azure App Service. The extension provides all necessary components. Installing the MSI may cause conflicts.
+</div>
+
+<div class="alert alert-info">
+Looking for Azure Functions instead? See <a href="/serverless/azure_functions/">Azure Functions Setup</a>. Using Linux? See <a href="/serverless/azure_app_service/linux_code">Linux Code</a> or <a href="/serverless/azure_app_service/linux_container">Linux Container</a> setup.
+</div>
+
 ## Installation
 Datadog recommends doing regular updates to the latest version of the extension to ensure optimal performance, stability, and availability of features. Note that both the initial install and subsequent updates require your web app to be fully stopped in order to install/update successfully.
 
@@ -553,6 +570,15 @@ It is likely that you do not have the Azure integration configured to monitor yo
 
 Still need help? Contact [Datadog support][5].
 
+## Additional Resources
+
+- [Tracing .NET Core Applications](/tracing/trace_collection/automatic_instrumentation/dd_libraries/dotnet-core) - Foundational APM concepts
+- [Tracing .NET Framework Applications](/tracing/trace_collection/automatic_instrumentation/dd_libraries/dotnet-framework) - Framework-specific guidance
+- [.NET Core Library Configuration](/tracing/trace_collection/library_config/dotnet-core/) - All configuration options
+- [.NET Framework Library Configuration](/tracing/trace_collection/library_config/dotnet-framework/) - Framework configuration
+- [.NET Custom Instrumentation](/tracing/trace_collection/custom_instrumentation/dotnet/) - Adding custom spans
+- [.NET Diagnostic Tool](/tracing/troubleshooting/dotnet_diagnostic_tool) - Troubleshooting traces
+
 ### Further Reading
 
 {{< partial name="whats-next/whats-next.html" >}}