name: feature-creator description: Guide for creating DevContainer features. Use when creating a new feature for devcontainer, implementing install.sh scripts (npm package, binary download, source build, dotnet tool, or directory setup patterns), or configuring devcontainer-feature.json metadata. Triggers on phrases like "create a feature", "add devcontainer feature", "install.sh template", or "devcontainer-feature.json".

DevContainer Feature Creator

Create DevContainer features efficiently using proven patterns from this repository.

Feature Structure

Every feature consists of exactly two files:

features/<feature-name>/
├── devcontainer-feature.json  # Metadata definition
└── install.sh                 # Installation script

devcontainer-feature.json Schema

Required Fields

{
  "id": "<feature-name>", // kebab-case, matches folder name
  "version": "1.0.0", // semver format
  "name": "Human Readable Name",
  "description": "Brief description of what this feature installs"
}

Optional Fields

{
  "options": {
    "version": {
      "type": "string",
      "default": "latest",
      "description": "Version to install"
    }
  },
  "installsAfter": [
    "ghcr.io/devcontainers/features/node" // Dependencies
  ],
  "postStartCommand": "command to run after container starts"
}

install.sh Patterns

Five proven patterns exist. See references/install-patterns.md for complete templates.

Creation Workflow

Step 1: Initialize Feature

Run the initialization script:

python3 scripts/init_feature.py <feature-name> <pattern>

Patterns: npm, binary, source, dotnet, setup

Step 2: Edit devcontainer-feature.json

1. Update name and description
2. Add options if configurable (e.g., version)
3. Add installsAfter if dependencies exist

Step 3: Edit install.sh

1. Replace placeholder values
2. Add error handling
3. Test installation

Step 4: Test Feature

# Build and test locally
devcontainer features test -f <feature-name> .

Best Practices

install.sh Guidelines

1. Always start with: #!/bin/bash and set -e
2. Version handling: VERSION="${VERSION:-default}"
3. Architecture detection (for binaries):

   ARCH=$(dpkg --print-architecture)
   case "$ARCH" in
       amd64) TARGET_ARCH="x86_64" ;;
       arm64) TARGET_ARCH="arm64" ;;
       *) echo "Unsupported: $ARCH"; exit 1 ;;
   esac
   

4. Dependency checks: Verify required tools before use
5. Cleanup: Remove temp files and apt cache
6. Verification: Confirm installation succeeded

Error Handling

• Check command availability before use
• Provide clear error messages
• Exit with non-zero code on failure
• Validate downloaded files (check gzip magic bytes)

User Context

For user-specific installations:

INSTALL_USER="${_REMOTE_USER:-${USERNAME:-vscode}}"
USER_HOME=$(getent passwd "${INSTALL_USER}" | cut -d: -f6)

Resources

• Initialization script: scripts/init_feature.py - Generate feature scaffolding
• Pattern templates: references/install-patterns.md - Detailed templates for each pattern