Local Docker Builds

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.

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.

Building Locally

Mount your application source code and the Docker socket, then run migetpacks:

macOS
Windows (PowerShell)
Linux

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

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

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.

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

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=python \
  miget/migetpacks:latest

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=ruby \
  miget/migetpacks:latest

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

Debugging Tips

Inspect Built Image Contents

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

Check Environment Variables

docker run --rm my-app:local env

View the Generated Dockerfile

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

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.

Check Exposed Ports

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

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

Source Mount Options

Read-Only Mount (Recommended)
Read-Write Mount
Subdirectory (Monorepo)

Mount the source as read-only to prevent any modifications:

-v /path/to/your/app:/workspace/source:ro

If your build process needs to write to the source directory:

-v /path/to/your/app:/workspace/source

For monorepo projects, mount the entire repo and use PROJECT_PATH:

-v /path/to/monorepo:/workspace/source:ro \
-e PROJECT_PATH=services/api

Getting Started

Guides

Configuration

Languages

Deploying

Reference

Overview

Prerequisites

Building Locally

Language Override

Custom Environment Variables

Debugging Tips

Inspect Built Image Contents

Check Environment Variables

View the Generated Dockerfile

Interactive Shell

Check Exposed Ports

Architecture Override

Source Mount Options

​Overview

​Prerequisites

​Building Locally

​Language Override

​Custom Environment Variables

​Debugging Tips

​Inspect Built Image Contents

​Check Environment Variables

​View the Generated Dockerfile

​Interactive Shell

​Check Exposed Ports

​Architecture Override

​Source Mount Options

Overview

Prerequisites

Building Locally

Language Override

Custom Environment Variables

Debugging Tips

Inspect Built Image Contents

Check Environment Variables

View the Generated Dockerfile

Interactive Shell

Check Exposed Ports

Architecture Override

Source Mount Options