03a-create-venv.sh

#!/usr/bin/env bash
# Step 3a: create an empty Python venv so downstream install steps that need
# it (dashboard, cybersec dataset fetch) can run before PyTorch is installed.
# 04-install-pytorch.sh later populates this same venv with torch + friends.
set -euo pipefail

VENV_DIR="${VENV_DIR:-/workspace/venv}"

if [[ -x "$VENV_DIR/bin/python" ]]; then
    echo "==> venv already exists at $VENV_DIR — nothing to do."
    exit 0
fi

if ! command -v python3 >/dev/null 2>&1; then
    echo "ERROR: python3 not found. Run ./02-install-prerequisites.sh first."
    exit 1
fi

# Make sure the parent dir exists and is writable. Needed on fresh
# hosts/containers where /workspace doesn't exist yet.
VENV_PARENT="$(dirname "$VENV_DIR")"
if [[ ! -d "$VENV_PARENT" ]]; then
    echo "==> Creating parent directory $VENV_PARENT"
    sudo mkdir -p "$VENV_PARENT"
    sudo chown "$(id -u):$(id -g)" "$VENV_PARENT" 2>/dev/null || true
fi

echo "==> Creating empty Python venv at $VENV_DIR"
python3 -m venv "$VENV_DIR"

# shellcheck disable=SC1091
source "$VENV_DIR/bin/activate"
pip install --quiet --upgrade pip setuptools wheel
deactivate

echo "==> Empty venv ready at $VENV_DIR"