Letter

LaTeX document generation over HTTP

About

Letter is a simple Go webserver that allows generation of LaTeX documents. Designed to be run in a Docker container.

Usage

Letter accepts input files in a .zip archive. This archive should contain all resources needed for your document. Letter builds the document with Tectonic and provides you with the resulting PDF file.

Synchronous API POST /sync

This endpoint builds the PDF synchronously and sends it in the HTTP response. Expects multipart form request with the following fields:

• file - the .tar archive containing all input files and resources
• entrypoint - name of .tex file which will be passed to LuaLaTeX

On success, Letter returns the generated PDF file. When an error happens, Letter returns JSON response containing error (error description) and tectonic_output (Tectonic log).

Asynchronous API POST /async

This endpoint builds the PDF in the background and sends it in callback request. Expects the same fields as the synchronous API, plus:

• callback - URL to which will Letter send the resulting PDF

The callback URL will receive a POST request from Letter with multipart data:

• file - the resulting PDF
• tectonic_output - Tectonic log
• error - error description (if available)

Authentication

Letter can be configured to require authentication. We expect X-Token header to contain a authentication token equal to the value of AUTH_TOKEN environment variable.

If AUTH_TOKEN environment variable is not set, Letter will not require authentication.

Running

A Dockerfile is provided that builds and runs Letter. Letter runs on port 8080 by default, this can be changed using PORT environment variable.

Requirements

• GoLang 1.21 (or newer)
• Tectonic