# Python Dependencies — Compliance xlsx Parsing

`parse_compliance_xlsx.py` requires `pandas` and `openpyxl`. This doc
explains how each server has (or should have) these installed.

---

## Dev server — how it works

Pandas and openpyxl are installed as **system apt packages**, not via pip
or a venv. This is why there is no venv on dev and no `--break-system-packages`
gymnastics. They were installed at some point via:

```bash
apt install python3-pandas python3-openpyxl
```

You can verify with:

```bash
python3 -c "import pandas; print(pandas.__file__)"
# /usr/lib/python3/dist-packages/pandas/__init__.py  ← apt-managed
```

---

## Production server — how to fix it

Production was missing pandas entirely. The fix mirrors what dev has:

```bash
apt-get update --fix-missing
apt install -y python3-pandas python3-openpyxl
```

No venv, no pip, no `PYTHON_BIN` env var needed. After installing, restart
the backend and the compliance xlsx upload will work.

---

## If apt packages are unavailable (fallback)

If you're on a system where apt doesn't have pandas (unlikely on Ubuntu
22.04/24.04), or you want isolation, use a venv:

```bash
apt install -y python3-venv python3-full
python3 -m venv /home/cve-dashboard/venv
/home/cve-dashboard/venv/bin/pip install -r /home/cve-dashboard/backend/scripts/requirements.txt
```

Then set `PYTHON_BIN` in the Node backend's environment:

```bash
export PYTHON_BIN=/home/cve-dashboard/venv/bin/python3
```

The backend reads `process.env.PYTHON_BIN` and falls back to `python3` if
not set, so this only needs to be done if you're using a venv.

---

## Why pip3 may fail on modern Ubuntu/Debian

PEP 668 (enforced in Ubuntu 23.04+) blocks `pip3 install` system-wide to
prevent breaking apt-managed packages. The error looks like:

```
error: externally-managed-environment
```

Using `apt install python3-pandas` is the correct solution — pip is not
needed when the distro packages the library directly.
