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Overview

migetpacks can build container images locally using your Docker socket. When OUTPUT_IMAGE does not contain a registry prefix, the built image stays on your local Docker daemon and is never pushed to a remote registry.

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Prerequisites

  • Docker Desktop (Mac/Windows) or Docker Engine (Linux)
  • Docker daemon running
  • The migetpacks image pulled locally
docker pull miget/migetpacks:latest
migetpacks uses Docker-in-Docker internally. Docker Desktop on Mac and Windows handles this transparently through its Linux VM. No --privileged flag or special configuration is needed.

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Building Locally

Mount your application source code and the Docker socket, then run migetpacks: 
docker run --rm \
  -v $(pwd):/workspace/source:ro \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -e OUTPUT_IMAGE=my-app:local \
  miget/migetpacks:latest
Then test the built image: 
docker run --rm -p 5000:5000 my-app:local
When OUTPUT_IMAGE does not contain a / with a registry domain (e.g., my-app:local vs registry.io/my-app:latest), the builder uses the local Docker daemon and the image will not be pushed.

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Language Override

By default, migetpacks auto-detects the language. You can override this with the LANGUAGE environment variable: 
docker run --rm \
  -v /path/to/your/app:/workspace/source:ro \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -e OUTPUT_IMAGE=my-app:local \
  -e LANGUAGE=nodejs \
  miget/migetpacks:latest

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Custom Environment Variables

Any environment variable not recognized by migetpacks is automatically injected into the generated Dockerfile as an ENV statement: 
docker run --rm \
  -v /path/to/your/app:/workspace/source:ro \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -e OUTPUT_IMAGE=my-app:local \
  -e NODE_OPTIONS="--max-old-space-size=4096" \
  -e NEXT_PUBLIC_API_URL="http://localhost:3000" \
  miget/migetpacks:latest

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Debugging Tips

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Inspect Built Image Contents

docker run --rm my-app:local ls -la /app/

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Check Environment Variables

docker run --rm my-app:local env

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View the Generated Dockerfile

The build output includes the generated Dockerfile content. Look for the Dockerfile.runtime section in the build logs.

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Interactive Shell

If the build succeeds but the app does not start correctly, you can override the entrypoint: 
docker run --rm -it --entrypoint /bin/sh my-app:local
DHI (Docker Hardened Images) containers are distroless and do not have a shell. You cannot use --entrypoint /bin/sh with DHI-built images. Use standard (non-DHI) builds for debugging.

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Check Exposed Ports

docker inspect my-app:local --format='{{json .Config.ExposedPorts}}'

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Architecture Override

By default, migetpacks builds for x86_64. To build for a different architecture: 
docker run --rm \
  -v /path/to/your/app:/workspace/source:ro \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -e OUTPUT_IMAGE=my-app:local \
  -e ARCH=arm64 \
  miget/migetpacks:latest

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Source Mount Options