A Docker Desktop extension that builds minimal container images using the Dalec BuildKit frontend. Pick an OS target, select the packages you need, preview the generated Dalec spec, and build — all from a single tab inside Docker Desktop.
Warning
Alpha — interfaces and behavior may change between versions. Not yet published to the Docker Marketplace; install from source.
- Select a Dalec build target (Azure Linux, Mariner, AlmaLinux, Rocky, Debian, Ubuntu, Fedora, openSUSE, Windows cross)
- Pick packages across four dependency scopes (
runtime,build,recommends,test) with optional version constraints - Configure image metadata (name, version, description, license, entrypoint, cmd, workdir, user, env vars, labels)
- Preview the generated Dalec YAML spec and the exact
docker buildcommand - Run the build and stream logs back into the UI
- Copy the image name, digest, or the generated spec with one click
- Docker Desktop 4.8+ with the extensions framework enabled
- BuildKit (bundled with recent Docker Desktop releases — no extra setup)
- On first build, Docker will pull the Dalec frontend image from
ghcr.io/project-dalec/dalec/frontend:latest
Until the extension is published to the Marketplace, install from source:
git clone https://github.com/project-dalec/dalec-docker-desktop-extension
cd dalec-docker-desktop-extension
make install-extensionThis builds dalec/dalec-docker-extension:latest and installs it into Docker Desktop. Open Docker Desktop — a Dalec tab appears in the left sidebar.
To update after pulling changes:
make update-extensionTo remove:
docker extension rm dalec/dalec-docker-extension:latestThe UI is a three-step flow.
Choose an OS target, add packages to the relevant dependency scopes (runtime / build / recommends / test), and fill in image metadata (name, version, license, entrypoint, cmd, and so on). Fields show example placeholders where defaults are ambiguous.
Review the generated Dalec YAML and the docker build command that will be run. Editing is not in-place; go back to step 1 to change anything.
Logs stream live while the build runs.
On success, the Image Details card shows the image name, digest, target, and package count, with copy buttons and a "New build" shortcut.
After a successful build the image exists in your local Docker daemon — use it with docker run, docker inspect, or push it to a registry like any other image.
Targets are fetched dynamically from the Dalec frontend at runtime. If that call fails, the UI falls back to this list:
| Family | Targets |
|---|---|
| RPM | Azure Linux 3, CBL-Mariner 2, AlmaLinux 8/9, Rocky Linux 8/9, Fedora 40, openSUSE Leap 15.5 |
| Debian/Ubuntu | Debian Bullseye/Bookworm/Trixie, Ubuntu Bionic/Focal/Jammy/Noble |
| Windows | windowscross |
backend/ Express + TypeScript service that runs inside the extension VM and shells out to docker
ui/ React + MUI frontend served by Docker Desktop
docs/ ARCHITECTURE, TESTING, DEBUGGING
Dockerfile Multi-stage build for the extension image
Makefile Build / install / update / push / test targets
The UI talks to the backend through ddClient from @docker/extension-api-client, which is only injected inside Docker Desktop's extension iframe. That means a standalone Vite dev server won't work — any change (frontend or backend) requires rebuilding and reinstalling the extension:
make update-extensionTo open Chrome DevTools for the extension panel:
docker extension dev debug dalec/dalec-docker-extension:latestTo stop auto-opening DevTools:
docker extension dev reset dalec/dalec-docker-extension:latestmake test # runs backend + UI unit testsType-checking separately:
cd ui && npm run typecheck
cd backend && npx tsc --noEmitHigh level: the UI talks to the backend over the extension framework's ddClient (no host network exposure); the backend validates the payload, writes the generated spec into a temp directory, and spawns docker build with DOCKER_BUILDKIT=1. Logs are buffered per build and pulled by the UI via HTTP polling against /api/build/:id/status. Build records expire 10 minutes after completion.
For a deeper walkthrough see docs/ARCHITECTURE.md. For debugging tips see docs/DEBUGGING.md.
- Dalec — the BuildKit frontend this extension drives
- Docker Extensions SDK
- BuildKit