Adds a multi-stage Dockerfile producing an image that works on Ampere through
Blackwell (sm_80 through sm_120: A100, RTX 30/40, H100, B100/B200, RTX 50-series,
RTX 6000 Pro Blackwell). The build itself requires no GPU at all and runs on a
free GitHub-hosted ubuntu-latest runner.
How the GPU-less build works:
1. cu128 PyTorch wheels are fat binaries. torch._C._cuda_getArchFlags() returns
'sm_70 sm_75 sm_80 sm_86 sm_90 sm_100 sm_120' regardless of which GPU
compiled the image, because the wheels are cross-compiled upstream by the
PyTorch team.
2. All deps resolve in a single uv pip install pass with explicit pins
(torch==2.10.0, --extra-index-url cu128, no --torch-backend=auto, no
install.sh). This prevents the silent cu cascade where bitsandbytes'
transitive cuda-toolkit==13 dep upgrades torch to 2.12+cu130 in a later
resolver pass, leaving xformers and other cu128 wheels stranded.
3. Build-time verification uses package metadata (importlib.metadata.version)
and the raw torch._C._cuda_getArchFlags() accessor. We deliberately avoid
import unsloth at build time because unsloth.__init__ calls
torch.cuda.get_device_properties(0), which requires an actual CUDA device
and is not bypassable. Import-time correctness is exercised at deploy time
by smoke_test.py with --gpus all.
4. UNSLOTH_COMPILE_DISABLE=1 and CUDA_VISIBLE_DEVICES="" during the build stage
prevent any code path from JIT-compiling kernels for the build host's
compute capability and baking the resulting cache into the image. The
deploy GPU produces its own cache on first use.
Other notes:
- --index-strategy unsafe-best-match is needed because the PyTorch wheel index
serves an old requests==2.28.1 that conflicts with datasets>=2.32.2, which
the default first-index-wins strategy rejects.
- Extra is cu128-ampere-torch2100 (ampere precedes the torch version in the
pyproject ordering).
- No flash-attn in the base image. FA3 is hard-refused on Blackwell upstream
and unsloth gracefully falls back to xformers + SDPA. Users on Ampere /
Ada / Hopper who want FA2 can pip install flash-attn on top.
- Two stages: nvidia/cuda:12.8.1-cudnn-devel-ubuntu24.04 for the build,
-cudnn-runtime for the deploy image. No nvcc in the published image.
- A lockfile is emitted at /opt/unsloth-venv/requirements.lock.txt inside
the image and can be extracted with docker/freeze.sh for byte-identical
rebuilds even after PyPI moves on.
CI workflow .github/workflows/docker-publish.yml:
- Builds on ubuntu-latest on every push to main, every tag, weekly via cron,
and manually via workflow_dispatch. Pushes to docker.io/unsloth/unsloth
with cache via type=gha.
- Optional smoke-test job runs on a self-hosted GPU runner if vars.HAS_GPU_RUNNER
is set; skipped otherwise. End-to-end verification on sm_120 hardware is a
nice-to-have, not a publish blocker.
Validation:
- Install path validated on a B200 host with CUDA_VISIBLE_DEVICES="" set
(simulating the GPU-less CI runner): torch 2.10.0+cu128 holds, xformers
0.0.34, bitsandbytes 0.49.2, triton 3.6.0, transformers 5.5.0, trl 0.24.0,
peft 0.19.1, accelerate 1.13.0. Arch flags include sm_100 and sm_120.
- Runtime path validated end-to-end on B200: smoke_test.py imports unsloth,
loads Llama-3.2-1B-Instruct-bnb-4bit in 4-bit, completes 5 LoRA steps with
loss decreasing 4.11 -> 3.75. xformers fallback active as designed.
Files:
- docker/Dockerfile multi-stage cu128 build
- docker/build.sh local build wrapper
- docker/freeze.sh extract lockfile from a built image
- docker/smoke_test.py runtime verification, run with --gpus all
- docker/.dockerignore
- .github/workflows/docker-publish.yml
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