.devcontainer/README.md

Devcontainer Configuration

This directory contains the VS Code devcontainer configuration for Roslyn-Stone development.

Features

• Base Image: Official Microsoft .NET devcontainer with .NET SDK 10.0
• Docker-in-Docker: Docker feature enabled via devcontainer features
• VS Code Extensions: Pre-configured C# development tools
• Non-root User: Development as vscode user with Docker access
• .NET Configuration: Optimized environment variables for development

Docker-in-Docker Support

The devcontainer includes the docker-in-docker feature which provides full Docker support, allowing you to:

• Build Docker images from within the container
• Run Docker containers for testing
• Test containerized deployments of Roslyn-Stone
• Develop and test Docker-based workflows

Testing Docker-in-Docker

After opening the project in the devcontainer, verify Docker is working:

# Check Docker is available
docker --version

# Run a test container
docker run --rm hello-world

# Build and run a test image
echo 'FROM alpine:latest' > /tmp/Dockerfile.test
echo 'CMD ["echo", "Docker-in-Docker is working!"]' >> /tmp/Dockerfile.test
docker build -t dind-test -f /tmp/Dockerfile.test /tmp
docker run --rm dind-test
docker rmi dind-test

Quick Start

1. Open this repository in VS Code
2. Install the "Dev Containers" extension if not already installed
3. Press F1 and select "Dev Containers: Reopen in Container"
4. Wait for the container to build and the project to restore
5. Start developing!

Configuration Details

Dockerfile

The Dockerfile:

• Uses mcr.microsoft.com/devcontainers/dotnet:1-10.0 as the base image (includes .NET 10.0 SDK)
• Base image already includes the vscode user and common development tools
• Docker will be installed by the docker-in-docker feature from devcontainer.json
• Minimal and clean - relies on official Microsoft devcontainer images

devcontainer.json

The devcontainer configuration:

• Uses the docker-in-docker feature for full Docker support
• Runs the container as the vscode user
• Sets .NET environment variables to optimize development experience
• Configures VS Code extensions for C#, Docker, and GitHub integration
• Runs dotnet restore && dotnet build after container creation

Environment Variables

The following .NET environment variables are configured:

• DOTNET_CLI_TELEMETRY_OPTOUT=1 - Disables telemetry
• DOTNET_GENERATE_ASPNET_CERTIFICATE=0 - Skips HTTPS dev certificate
• DOTNET_NOLOGO=1 - Suppresses .NET logo output
• DOTNET_USE_POLLING_FILE_WATCHER=1 - Uses polling for file watching (better for containers)

Post-Create Command

The devcontainer automatically runs dotnet restore && dotnet build after creation to ensure the project is ready for development.

Customization

Adding VS Code Extensions

Edit the extensions array in devcontainer.json:

"customizations": {
  "vscode": {
    "extensions": [
      "your.extension.id"
    ]
  }
}

Adding System Packages

Edit the Dockerfile to install additional packages:

RUN apt-get update && apt-get install -y \
    your-package-name \
    && apt-get clean && rm -rf /var/lib/apt/lists/*

Adding .NET Tools

Install tools in the post-create command or manually after container starts:

dotnet tool install -g your-tool-name

Troubleshooting

Docker-in-Docker Not Working

If Docker commands fail inside the container:

1. Ensure Docker is running on your host machine
2. Check that the docker-in-docker feature is enabled in devcontainer.json
3. Try rebuilding the container: "Dev Containers: Rebuild Container"
4. Check Docker daemon status: sudo service docker status or docker info
5. Verify the vscode user has Docker access: groups (should include docker)

Build Failures

If the post-create command fails:

1. Check internet connectivity
2. Verify NuGet feeds are accessible
3. Manually run dotnet restore and check for errors
4. Review the devcontainer creation logs

Permission Issues

If you encounter permission issues with Docker:

1. Verify the vscode user is in the docker group: groups
2. Rebuild the container to ensure the docker-in-docker feature is properly configured
3. Try restarting the Docker daemon if needed

References

• VS Code Dev Containers
• Docker-in-Docker Feature
• .NET Dev Container Images
• Microsoft Devcontainers Documentation