Build and Dependency Guide Skill

Build and Dependency Guide

Docker Images

Build the release image (includes all dependencies and pre-fetched venvs):

# Build from local source
docker buildx build -f docker/Dockerfile --tag nemo-rl:latest .

# Build from a specific git ref (no local clone needed)
docker buildx build -f docker/Dockerfile \
    --build-arg NRL_GIT_REF=main \
    --tag nemo-rl:latest \
    https://github.com/NVIDIA-NeMo/RL.git

Skip optional backends to reduce build time:

# Skip vLLM and SGLang
docker buildx build -f docker/Dockerfile \
    --build-arg SKIP_VLLM_BUILD=1 \
    --build-arg SKIP_SGLANG_BUILD=1 \
    --tag nemo-rl:latest .

See @docs/docker.md for full options.

Always Use uv

Never use pip install directly — always go through uv.

# Run a script
uv run examples/run_grpo.py

# Run tests
uv run --group test bash tests/run_unit.sh

# Install all deps from lockfile
uv sync --locked

Exception: Dockerfile.ngc_pytorch is exempt from this rule.

Adding Dependencies

# Add a runtime dependency
uv add <package>

# Add an optional dependency
uv add --optional --extra <group> <package>

# Regenerate the lockfile after changes
uv lock

Commit both pyproject.toml and uv.lock together:

git add pyproject.toml uv.lock
git commit -s -m "build: add <package> dependency"

Common Pitfalls

| Problem | Cause | Fix | |---------|-------|-----| | uv sync --locked fails | Dependency conflict or stale lockfile | Re-run uv lock and commit updated lock | | ModuleNotFoundError after pip install | pip installed outside uv-managed venv | Use uv add + uv sync, never bare pip install | | Docker build fails at vLLM | vLLM build time overhead | Pass --build-arg SKIP_VLLM_BUILD=1 |

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