Gotenberg
A stateless API for converting Markdown files, HTML files and Office documents to PDF
---
At TheCodingMachine, we build a lot of web applications (intranets, extranets and so on) which require to generate PDF from
various sources. Each time, we end up using some well known libraries like **wkhtmltopdf** or **unoconv** and kind of losing time by
reimplementing a solution from a project to another project. Meh.
# Menu
* [Usage](#usage)
* [Security](#security)
* [Scalability](#scalability)
* [Custom implementation](#custom-implementation)
## Usage
Let's say you're starting the API using this simple command:
```sh
$ docker run --rm -p 3000:3000 thecodingmachine/gotenberg:1.0.0
```
The API is now available on your host under `http://127.0.0.1:3000`.
It accepts `POST` requests with a `multipart/form-data` Content-Type. Your form data should provide one or more files to convert.
It currently accepts the following:
* Markdown files
* HTML files
* Office documents (.docx, .doc, .odt, .pptx, .ppt, .odp and so on)
* PDF files (if more than one file to convert)
**Heads up:** the API relies on the file extension to determine which library to use for conversion.
There are two use cases:
* If you send one file, it will convert it and return the resulting PDF
* If many files, it will convert them to PDF, merge the resulting PDFs into a single PDF and return it
## Security
The API does not provide any authentication mechanisms. Make sure to not put it on a public facing port and your client(s) should always
controls what's is sent to the API.
## Scalability
Some libraries like **unoconv** cannot perform concurrent conversions. That's why the API does only one conversion at a time.
If your API is under heavy load, a request will take time to be processed.
Fortunately, you may pass through this limitation by scaling the API.
In the following example, I'll demonstrate how to do some vertical scaling (= on the same machine) with Docker Compose, but of course horizontal scaling works too!
```yaml
version: '3'
services:
# your other services
gotenberg-proxy:
# Traefik is a powerful HTTP reverse proxy which allows us to do some load-balancing.
# It provides various methods of load-balancing which are not described here.
# More information: https://traefik.io/
image: traefik:1.5-alpine
command: --docker --logLevel=DEBUG
volumes:
- /var/run/docker.sock:/var/run/docker.sock:ro
gotenberg:
image: gotenberg:1.0.0
labels:
- traefik.backend=gotenberg
- traefik.frontend.rule=Host:gotenberg.yourdomain.com
- traefik.port=3000
```
You may now launch your services using:
```sh
docker-compose up --scale gotenberg=your_number_of_instances
```
When requesting `gotenberg.yourdomain.com` with your client(s), Traefik will automatically redirect a request to a Gotenberg container
according to the load-balancing strategy you have defined.
## Custom implementation
The API relies on a simple YAML configuration file called `gotenberg.yml`. It allows you to tweak some values and even provides you
a way to change the commands called for each kind of conversion.
The default configuration is located here: [.ci/gotenberg.yml](.ci/gotenberg.yml)
---
Would you like to update this documentation ? Feel free to open an [issue](../../issues).