# 113 — Stirling PDF Deployment Guide

> Status: **PLANNED** — not yet deployed
> CT ID: 113 · IP: 192.168.1.113
> Domain: `pdf.spendlik.sk`
> Last updated: 2026-06-22

---

## Overview

Stirling PDF is a self-hosted, open-source PDF toolkit with 50+ operations (merge, split, OCR, compress, convert, redact, sign, rotate, watermark, etc.). All processing happens locally — no documents leave the network.

Primary use case in this homelab: PDF preprocessing for the Paperless-ngx pipeline (CT 111). Potential n8n integration for automated document processing.

Stack: single Docker container (Java/Spring backend + Next.js frontend), no database required.

---

## Resource Allocation

| Resource | Allocation |
|---|---|
| **CT ID** | 113 |
| **IP** | 192.168.1.113 |
| **CPUs** | 2 |
| **RAM** | 1 GB (idle ~512 MB; OCR/conversion peaks higher) |
| **Disk** | 8 GB |
| **Template** | Debian 13 (trixie) |
| **Privileged** | Yes (Docker requires it) |
| **Nesting** | Enabled (`features: nesting=1`) |

---

## Phase 1 — Create LXC Container

In the Proxmox web UI terminal on the host:

```bash
pct create 113 local:vztmpl/debian-13-standard_13.0-1_amd64.tar.zst \
  --hostname stirling-pdf \
  --cores 2 \
  --memory 1024 \
  --swap 512 \
  --rootfs local-lvm:8 \
  --net0 name=eth0,bridge=vmbr0,ip=192.168.1.113/24,gw=192.168.1.1 \
  --unprivileged 0 \
  --features nesting=1 \
  --ostype debian \
  --start 1
```

Enter the container:

```bash
pct enter 113
```

---

## Phase 2 — Base Setup

```bash
apt update && apt upgrade -y
apt install -y nano curl ca-certificates gnupg lsb-release
```

---

## Phase 3 — Install Docker

```bash
install -m 0755 -d /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/debian/gpg | gpg --dearmor -o /etc/apt/keyrings/docker.gpg
chmod a+r /etc/apt/keyrings/docker.gpg

echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] \
  https://download.docker.com/linux/debian \
  $(lsb_release -cs) stable" | tee /etc/apt/sources.list.d/docker.list > /dev/null

apt update
apt install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin
```

Verify:

```bash
docker run --rm hello-world
```

---

## Phase 4 — Deploy Stirling PDF

```bash
mkdir -p /opt/stirling-pdf
cd /opt/stirling-pdf
nano docker-compose.yml
```

Paste:

```yaml
services:
  stirling-pdf:
    image: stirlingtools/stirling-pdf:latest
    container_name: stirling-pdf
    restart: unless-stopped
    ports:
      - "8080:8080"
    volumes:
      - ./trainingData:/usr/share/tessdata
      - ./extraConfigs:/configs
      - ./logs:/logs
    environment:
      - DOCKER_ENABLE_SECURITY=false
      - INSTALL_BOOK_AND_ADVANCED_HTML_OPS=false
      - LANGS=en_GB
```

> ⚠️ `DOCKER_ENABLE_SECURITY=false` is correct for setups where authentication is handled externally by Authelia. Do not enable internal login as well — it conflicts.

Start:

```bash
docker compose up -d
docker compose logs -f
```

Wait for the message `Started StirlingPDFApplication`. Then verify locally:

```bash
curl -s http://localhost:8080 | grep -i stirling
```

---

## Phase 5 — nginx Reverse Proxy (CT 101)

Enter CT 101:

```bash
pct enter 101
nano /etc/nginx/sites-available/stirling-pdf
```

Paste:

```nginx
server {
    listen 80;
    server_name pdf.spendlik.sk;

    location / {
        proxy_pass http://192.168.1.113:8080;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        client_max_body_size 100M;
    }
}
```

> ⚠️ `client_max_body_size 100M` is important — large PDFs will be rejected without it.

Enable and reload:

```bash
ln -s /etc/nginx/sites-available/stirling-pdf /etc/nginx/sites-enabled/
nginx -t && systemctl reload nginx
```

---

## Phase 6 — SSL Certificate

Still in CT 101:

```bash
certbot --nginx -d pdf.spendlik.sk
```

> ⚠️ After certbot runs, always inspect the config:

```bash
cat /etc/nginx/sites-available/stirling-pdf
```

Check for:
- Duplicate `server_name` directives
- Missing closing `}` brace
- `listen 443 ssl` block correctly added

If anything looks wrong, fix manually — do not re-run certbot without correcting first.

---

## Phase 7 — DNS Record

In WebSupport admin panel:

1. Add A record: `pdf` → current public IP
2. **Check both DNS management pages** — missing the second page has caused outages before
3. Note the numeric record ID assigned by WebSupport
4. Add the record ID to `00_index.md` DNS table

---

## Phase 8 — DDNS Updater (CT 108)

Enter CT 108:

```bash
pct enter 108
nano /usr/local/bin/ddns-update.sh
```

Add an entry for `pdf.spendlik.sk` using the record ID obtained in Phase 7, following the existing pattern in the script.

---

## Phase 9 — Authelia Protection (CT 102)

Enter CT 102:

```bash
pct enter 102
nano /etc/authelia/configuration.yml
```

In the `access_control.rules` section, add a bypass rule for the Stirling PDF API (needed if wiring to n8n) **before** the catch-all 2FA rule:

```yaml
- domain: pdf.spendlik.sk
  resources:
    - "^/api/.*"
  policy: bypass

- domain: pdf.spendlik.sk
  policy: two_factor
```

> ⚠️ Rule order is first-match-wins. The API bypass must precede the catch-all `two_factor` rule or n8n calls will be blocked by 2FA.

Restart Authelia:

```bash
docker compose restart
```

Add Authelia middleware to the nginx vhost in CT 101 (refer to how other Authelia-protected services are configured — e.g., `automation.spendlik.sk`).

---

## Phase 10 — Verify

Test from mobile data (not LAN — hairpin NAT):

- `https://pdf.spendlik.sk` loads and Authelia prompts for 2FA
- After login, Stirling PDF home page is accessible with all tool categories visible
- Upload a test PDF and run merge or compress — file should process and download

---

## API Integration with n8n

Stirling PDF exposes a full REST API. Swagger UI is available at:

```
https://pdf.spendlik.sk/swagger-ui/index.html
```

Example n8n HTTP Request node — compress a PDF:

```
POST https://pdf.spendlik.sk/api/v1/general/compress-pdf
Content-Type: multipart/form-data

fileInput: <binary PDF>
optimizeLevel: 3
```

> For API calls from n8n, the Authelia bypass rule on `/api/*` (Phase 9) allows Bearer-free requests from within the LAN.

Common operations available via API:

| Operation | Endpoint |
|---|---|
| Merge PDFs | `POST /api/v1/general/merge-pdfs` |
| Split PDF | `POST /api/v1/general/split-pdf` |
| Compress PDF | `POST /api/v1/general/compress-pdf` |
| PDF to image | `POST /api/v1/convert/pdf/img` |
| Add OCR layer | `POST /api/v1/misc/add-ocr-pdf` |
| Rotate pages | `POST /api/v1/general/rotate-pdf` |
| Remove metadata | `POST /api/v1/misc/remove-blanks` |

Full API reference at the Swagger UI on your instance after deployment.

---

## Paperless-ngx Integration Ideas

Stirling PDF sits naturally upstream of Paperless-ngx for preprocessing:

- **Compress oversized scans** before consume — reduces NAS storage for Modelář magazines
- **Rotate misaligned pages** from batch scans
- **Strip metadata** from sensitive documents before ingestion
- **OCR layer addition** for scanned PDFs that Paperless struggles with (though Paperless has its own OCR — use Stirling for pre-processing only when needed)

A simple n8n workflow pattern:

```
New file in NAS consume folder (webhook or poll)
  → Stirling PDF: compress + rotate
  → Save back to consume folder
  → Paperless picks it up automatically
```

---

## Resource Notes

- Idle RAM: ~512 MB
- OCR operations: can spike to ~800 MB temporarily
- LibreOffice conversions (PDF → DOCX etc.): heaviest operation, may need RAM bump to 2 GB if used frequently
- 2 CPU cores sufficient for single-user use

---

## Gotchas

| Issue | Fix |
|---|---|
| Large PDF uploads rejected | `client_max_body_size 100M` in nginx config |
| certbot corrupts nginx config | Always inspect after issuance |
| n8n API calls blocked by Authelia | Add `/api/*` bypass rule before catch-all |
| Container won't start after Proxmox reboot | Check `pct config 113` for boot order; add `--onboot 1` if missing |