# PostConvert

Image/PDF-to-JPEG conversion microservice. Single-file Node.js/Express app (`server.js`).

## Tech Stack

- Node.js 18+ (ES modules), Express
- Sharp (image processing), libheif-js (HEIC/HEIF via WASM)
- pdftoppm from Poppler (PDF rendering), archiver (ZIP output)
- Docker (node:20-bookworm-slim), deployed on Fly.io (sjc region)

## Endpoints

- `GET /health` — health check
- `POST /convert` — image or first PDF page → JPEG
- `POST /convert/pdf` — all PDF pages → ZIP of JPEGs

## Auth

Bearer token via `CONVERTER_TOKEN` env var on all endpoints.

## Key Design

- Single-flight concurrency (1 conversion at a time, 429 if busy)
- Resize/quality via headers: `x-jpeg-quality`, `x-max-dimension`, `x-pdf-dpi`, `x-without-enlargement`
- Pixel limit 200M, bounded /tmp, no stack traces leaked, request timeouts
- Fly.io auto-scaling 0–10 machines, 2 concurrent connection hard limit

## Environment Variables

- `PORT` (default 8080)
- `CONVERTER_TOKEN` (required)
- `REQ_TIMEOUT_MS` (default 120s, range 5–600s)
- `REQ_TIMEOUT_PDF_MS` (default 5m, range 10s–30m)

## Development

```sh
npm install
node server.js
```

Docker:
```sh
docker build -t postconvert .
docker run -e CONVERTER_TOKEN=secret -p 8080:8080 postconvert
```

## Fly.io Deployment

Tokens are in `.env` (gitignored). Load with `source .env` or use `dotenv`.

Deploy: `FLY_API_TOKEN="$FLY_API_TOKEN" fly deploy`