Packages

Asylum can install additional packages into a project-specific Docker image layer. When packages are configured, Asylum builds a project image on top of the base image.

Package Types

Packages are configured under each kit's config:

kits:
  apt:
    packages:
      - libpq-dev
      - redis-tools
  node:
    packages:
      - "@anthropic-ai/claude-mcp-server-filesystem"
      - tsx
  python:
    packages:
      - pandas
      - numpy
  shell:
    build:
      - "curl -fsSL https://deno.land/install.sh | sh"

Kit	Key	Installer	Runs as
apt	packages	apt-get install	root
node	packages	npm install -g	claude
python	packages	uv tool install	claude
shell	build	Executed as-is	claude

How It Works

When any packages are configured, Asylum:

1. Generates a project Dockerfile (FROM asylum:latest + install commands)
2. Builds a project image tagged asylum:proj-<hash>
3. Caches the image — rebuilds only when packages change

If no packages are configured, the base image (asylum:latest) is used directly.

Custom Build Commands

The shell kit's build key runs arbitrary commands during the project image build. Use this for tools that don't have a standard package manager:

kits:
  shell:
    build:
      - "curl -fsSL https://deno.land/install.sh | sh"
      - "go install golang.org/x/tools/gopls@latest"

Each command is executed as your host user. Commands must not contain newlines.