Guide · Agent skill
How to use the Containerize ASP.NET .NET Framework agent skill
Updated · written with AI from the project's own documentation and checked against our catalogue data
This guide explains how to use the containerize-aspnet-framework skill, a set of instructions that lets an AI agent package an older ASP.NET (.NET Framework, not .NET Core) web project into a Windows Docker container. It is written for readers who have never used agent skills before. By the end you will know what the skill does, how to install it, how to ask for it in plain language, and what you need in place before you run it.
Containerize ASP.NET .NET Frameworkgithub/awesome-copilot · MIT Download the skill Quick start
- 1Check your project. Confirm the project is an ASP.NET .NET Framework app with a .csproj file, not a .NET Core project.
- 2Install the NuGet package. Add Microsoft.Configuration.ConfigurationBuilders.Environment to the project yourself using the Visual Studio NuGet Package Manager or package manager console.
- 3Download and unzip the skill. Download the skill ZIP from this page and unzip it into ~/.claude/skills/ or the project's .claude/skills/ folder.
- 4Ask for containerization. Make a plain-language request that names the .csproj path and any choices for SKU, version, ports and user account.
- 5Answer any pause. If the agent stops to ask for the NuGet package, install it yourself and then tell the agent to continue.
- 6Review the output. Check the Dockerfile, .dockerignore, LogMonitorConfig.json, web.config and progress.md before you build the image.
- 7Build with Docker. Build the image with Docker on a machine that has Windows container support, then test the container locally.
What does this skill make the agent do?
A skill is a folder containing a SKILL.md file. That file holds a detailed checklist that an agent follows when you ask it to do a particular job. This skill's job is to containerize an ASP.NET .NET Framework project, focusing only on the changes needed for the app to run in a Windows Docker container.
Following the checklist, the agent reads the .csproj file to find the .NET Framework version (from the TargetFrameworkVersion element), chooses a matching Microsoft Windows Server base image, and writes a Dockerfile and .dockerignore file. It edits web.config so app settings and connection strings are read from environment variables, and it creates a progress.md file to track its work with check marks. It also creates a LogMonitorConfig.json file next to the Dockerfile, copied from a reference file in the skill.
- Reads your project's .csproj file and checks the TargetFrameworkVersion element
- Selects a Windows Server base image based on the SKU (Core or Full) and version you choose
- Writes a multi-stage Dockerfile and .dockerignore
- Updates web.config to use the EnvironmentConfigBuilder for appSettings and connectionStrings
- Tracks progress in progress.md
- Covers GAC assemblies, MSIs, COM components and IIS settings when you specify them
What you need before you start
The skill only works on a .NET Framework ASP.NET project that has a .csproj file. Modern .NET (Core, 5+) projects are out of scope, because the skill states that the containerization process differs for them. The skill also assumes Windows containers, so it is not suitable for Linux containers.
You need Docker with Windows container support and access to Microsoft's dotnet-framework-docker base images in the public registry. You must also install the NuGet package Microsoft.Configuration.ConfigurationBuilders.Environment in the project yourself. The agent will not install NuGet packages for you. If the package is missing, the agent is told to pause and ask you to add it with the Visual Studio NuGet Package Manager or the package manager console.
- A .NET Framework ASP.NET project with a .csproj file
- Docker with Windows container support
- NuGet package Microsoft.Configuration.ConfigurationBuilders.Environment, installed manually
- Access to Microsoft's dotnet-framework-docker base images (public registry)
How to install the skill
Download the skill ZIP from this page and unzip it. You can install it for yourself or for one project. For all of your projects, unzip it into ~/.claude/skills/. For a single project, unzip it into that project's .claude/skills/ folder.
If you use the Claude apps instead, upload the ZIP under Settings, then Capabilities, then Skills.
- Personal install: unzip into ~/.claude/skills/
- Project install: unzip into the project's .claude/skills/ folder
- Claude apps: upload the ZIP under Settings → Capabilities → Skills
How to trigger the skill with a natural request
You do not need a special command. Describe the job in plain language and name the project's .csproj file, because the skill needs that file to read the .NET Framework version. You can also state your choices for the Windows Server SKU and version, the user account the container should run as, the ports to expose, and any IIS settings.
The skill's settings list says that many fields can be left at their defaults. Core is the default SKU, and the defaults are shown in square brackets in the settings. Anything you do not specify falls back to those defaults.
- Name the .csproj path, for example: Containerize the ASP.NET project at src/MyLegacyApp/MyLegacyApp.csproj
- Set choices: Use Windows Server Full instead of Core, expose port 80, and run as ContainerUser
- List extra items: Register the GAC assembly I list below and install this MSI
- Ask for checks: Show me your progress.md when you finish
Containerize the ASP.NET .NET Framework project at src/MyLegacyApp/MyLegacyApp.csproj using the containerize-aspnet-framework skill. Use Windows Server Core and expose port 80.Review what the agent creates
The Dockerfile is designed as a multi-stage build. The build stage uses a Windows Server Core image to build the application, and the final stage copies the output into the runtime image. The skill also says to pick a base image tag that matches your .NET Framework version and your chosen SKU and Windows Server version. Tag listings are on the dotnet-framework-docker project's ASP.NET README, which the skill links to.
Read web.config after the change. The skill adds a configSections entry, a configBuilders section and the EnvironmentConfigBuilder, so that values can come from environment variables when the container runs. The full SKILL.md is longer than this summary, so read it for every step the agent follows.
- Dockerfile and .dockerignore in the project root
- LogMonitorConfig.json in the folder where the Dockerfile is created
- progress.md with check marks for each completed step
- Updated web.config using configBuilders for appSettings and connectionStrings
Safety notes: scripts and network
According to the skill's listing, this skill does not run scripts and does not use the network. The agent itself still edits files in your project, so review the changes before you build or commit them.
The skill tells the agent to stop and ask you before it installs NuGet packages. It also limits changes to what containerization requires and does not set up cloud infrastructure or change application code beyond that.
- No scripts are run by the skill
- No network use is listed for the skill
- Missing NuGet packages must be installed by you
- Cloud infrastructure is out of scope
Tips for better results
Fill in the optional settings whenever you know them. Custom build steps, GAC assemblies, MSIs, COM components, registry keys and IIS settings are all covered by the checklist, but the agent can only handle what you tell it. Listing them up front avoids a second round of edits.
Keep the LogMonitorConfig.json file as it is. The skill says its contents must match the reference exactly, because raising the logging level to Information for EventLog sources creates unnecessary noise.
- List GAC assemblies with their names and versions
- List MSIs and COM components that must be installed or registered
- Give the health check endpoint path if your app has one
- Confirm the NuGet package is installed before you start
What people use it for
- Moving a legacy ASP.NET Framework web app to Docker so it can run on a Windows Server based platform
- Producing a starting Dockerfile and web.config changes for a team that needs a repeatable Windows container setup
- Packaging an app that depends on GAC assemblies, MSIs or COM components, with those listed in the request
- Preparing an older IIS-hosted app to read its app settings and connection strings from environment variables
Frequently asked questions
Is the containerize ASP.NET .NET Framework skill free?
The skill is published under the MIT licence in the github/awesome-copilot repository. The source does not mention pricing, so check the repository for the licence terms that apply to your use.
How do I install the containerize-aspnet-framework skill?
Download the ZIP from this page and unzip it into ~/.claude/skills/ for all projects, or into the project's .claude/skills/ folder for one project. In the Claude apps, you can upload the ZIP under Settings → Capabilities → Skills.
What are the requirements for this skill?
You need a .NET Framework ASP.NET project with a .csproj file, Docker with Windows container support, the NuGet package Microsoft.Configuration.ConfigurationBuilders.Environment installed manually, and access to Microsoft's dotnet-framework-docker base images in the public registry.
Can this skill containerize a .NET Core or .NET 5+ project?
No. The skill targets .NET Framework only and states that the containerization process is different for .NET Core projects. Modern .NET projects need a different approach.
Does the agent install the NuGet package for me?
No. The skill tells the agent not to install missing NuGet packages. It pauses and asks you to install Microsoft.Configuration.ConfigurationBuilders.Environment yourself using Visual Studio.
Can I use this skill to create Linux containers?
No. The instructions assume Windows Server base images, so the skill is for Windows containers only.
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Our verdict
Use this skill if you maintain an older ASP.NET .NET Framework web app and want a Windows container setup with a repeatable checklist and a starting Dockerfile. Pick something else if your app is on modern .NET, if you need Linux containers, or if you expect the agent to handle cloud infrastructure or package installs for you.
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