convert-to-apple-container

name	convert-to-apple-container
description	Switch from Docker to Apple Container for macOS-native container isolation. Use when the user wants Apple Container instead of Docker, or is setting up on macOS and prefers the native runtime. Triggers on "apple container", "convert to apple container", "switch to apple container", or "use apple container". Use when this capability is needed.
metadata	{"author":"DingyangLyu"}

Convert to Apple Container

This skill switches MatClaw's container runtime from Docker to Apple Container (macOS-only). It uses the skills engine for deterministic code changes, then walks through verification.

What this changes:

• Container runtime binary: docker → container
• Mount syntax: -v path:path:ro → --mount type=bind,source=...,target=...,readonly
• Startup check: docker info → container system status (with auto-start)
• Orphan detection: docker ps --filter → container ls --format json
• Build script default: docker → container
• Dockerfile entrypoint: .env shadowing via mount --bind inside the container (Apple Container only supports directory mounts, not file mounts like Docker's /dev/null overlay)
• Container runner: main-group containers start as root for mount --bind, then drop privileges via setpriv

What stays the same:

• Mount security/allowlist validation
• All exported interfaces and IPC protocol
• Non-main container behavior (still uses --user flag)
• All other functionality

Prerequisites

Verify Apple Container is installed:

container --version && echo "Apple Container ready" || echo "Install Apple Container first"

If not installed:

• Download from https://github.com/apple/container/releases
• Install the .pkg file
• Verify: container --version

Apple Container requires macOS. It does not work on Linux.

Phase 1: Pre-flight

Check if already applied

Read .matclaw/state.yaml. If convert-to-apple-container is in applied_skills, skip to Phase 3 (Verify). The code changes are already in place.

Check current runtime

grep "CONTAINER_RUNTIME_BIN" src/container-runtime.ts

If it already shows 'container', the runtime is already Apple Container. Skip to Phase 3.

Phase 2: Apply Code Changes

Run the skills engine to apply this skill's code package. The package files are in this directory alongside this SKILL.md.

Initialize skills system (if needed)

If .matclaw/ directory doesn't exist yet:

npx tsx scripts/apply-skill.ts --init

Or call initSkillsSystem() from skills-engine/migrate.ts.

Apply the skill

npx tsx scripts/apply-skill.ts .claude/skills/convert-to-apple-container

This deterministically:

• Replaces src/container-runtime.ts with the Apple Container implementation
• Replaces src/container-runtime.test.ts with Apple Container-specific tests
• Updates src/container-runner.ts with .env shadow mount fix and privilege dropping
• Updates container/Dockerfile with entrypoint that shadows .env via mount --bind
• Updates container/build.sh to default to container runtime
• Records the application in .matclaw/state.yaml

If the apply reports merge conflicts, read the intent files:

• modify/src/container-runtime.ts.intent.md — what changed and invariants
• modify/src/container-runner.ts.intent.md — .env shadow and privilege drop changes
• modify/container/Dockerfile.intent.md — entrypoint changes for .env shadowing
• modify/container/build.sh.intent.md — what changed for build script

Validate code changes

npm test
npm run build

All tests must pass and build must be clean before proceeding.

Phase 3: Verify

Ensure Apple Container runtime is running

container system status || container system start

Build the container image

./container/build.sh

Test basic execution

echo '{}' | container run -i --entrypoint /bin/echo matclaw-agent:latest "Container OK"

Test readonly mounts

mkdir -p /tmp/test-ro && echo "test" > /tmp/test-ro/file.txt
container run --rm --entrypoint /bin/bash \
  --mount type=bind,source=/tmp/test-ro,target=/test,readonly \
  matclaw-agent:latest \
  -c "cat /test/file.txt && touch /test/new.txt 2>&1 || echo 'Write blocked (expected)'"
rm -rf /tmp/test-ro

Expected: Read succeeds, write fails with "Read-only file system".

Test read-write mounts

mkdir -p /tmp/test-rw
container run --rm --entrypoint /bin/bash \
  -v /tmp/test-rw:/test \
  matclaw-agent:latest \
  -c "echo 'test write' > /test/new.txt && cat /test/new.txt"
cat /tmp/test-rw/new.txt && rm -rf /tmp/test-rw

Expected: Both operations succeed.

Full integration test

npm run build
launchctl kickstart -k gui/$(id -u)/com.matclaw

Send a message via WhatsApp and verify the agent responds.

Troubleshooting

Apple Container not found:

• Download from https://github.com/apple/container/releases
• Install the .pkg file
• Verify: container --version

Runtime won't start:

container system start
container system status

Image build fails:

# Clean rebuild — Apple Container caches aggressively
container builder stop && container builder rm && container builder start
./container/build.sh

Container can't write to mounted directories: Check directory permissions on the host. The container runs as uid 1000.

Summary of Changed Files

File	Type of Change
src/container-runtime.ts	Full replacement — Docker → Apple Container API
src/container-runtime.test.ts	Full replacement — tests for Apple Container behavior
src/container-runner.ts	.env shadow mount removed, main containers start as root with privilege drop
container/Dockerfile	Entrypoint: mount --bind for .env shadowing, setpriv privilege drop
container/build.sh	Default runtime: docker → container

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Source: DingyangLyu/MatClaw — distributed by TomeVault.