forgejo/docs/content/doc/advanced/external-renderers.en-us.md

---
date: "2018-11-23:00:00+02:00"
title: "External renderers"
slug: "external-renderers"
weight: 40
toc: true
draft: false
menu:
  sidebar:
    parent: "advanced"
    name: "External renderers"
    weight: 40
    identifier: "external-renderers"
---

# Custom files rendering configuration

Gitea supports custom file renderings (i.e., Jupyter notebooks, asciidoc, etc.) through external binaries, 
it is just a matter of:

* installing external binaries
* add some configuration to your `app.ini` file
* restart your Gitea instance

This supports rendering of whole files. If you want to render code blocks in markdown you would need to do something with javascript. See some examples on the [Customizing Gitea](../customizing-gitea) page.

## Installing external binaries

In order to get file rendering through external binaries, their associated packages must be installed. 
If you're using a Docker image, your `Dockerfile` should contain something along this lines:

```
FROM gitea/gitea:{{< version >}}
[...]

COPY custom/app.ini /data/gitea/conf/app.ini
[...]

RUN apk --no-cache add asciidoctor freetype freetype-dev gcc g++ libpng python-dev py-pip python3-dev py3-pip py3-zmq
# install any other package you need for your external renderers

RUN pip3 install --upgrade pip
RUN pip3 install -U setuptools
RUN pip3 install jupyter matplotlib docutils 
# add above any other python package you may need to install
```

## `app.ini` file configuration

add one `[markup.XXXXX]` section per external renderer on your custom `app.ini`:

```
[markup.asciidoc]
ENABLED = true
FILE_EXTENSIONS = .adoc,.asciidoc
RENDER_COMMAND = "asciidoctor -e -a leveloffset=-1 --out-file=- -"
; Input is not a standard input but a file
IS_INPUT_FILE = false

[markup.jupyter]
ENABLED = true
FILE_EXTENSIONS = .ipynb
RENDER_COMMAND = "jupyter nbconvert --stdout --to html --template basic "
IS_INPUT_FILE = true

[markup.restructuredtext]
ENABLED = true
FILE_EXTENSIONS = .rst
RENDER_COMMAND = rst2html.py
IS_INPUT_FILE = false
```

If your external markup relies on additional classes and attributes on the generated HTML elements, you might need to enable custom sanitizer policies. Gitea uses the [`bluemonday`](https://godoc.org/github.com/microcosm-cc/bluemonday) package as our HTML sanitizier. The example below will support [KaTeX](https://katex.org/) output from [`pandoc`](https://pandoc.org/).

```ini
[markup.sanitizer]
; Pandoc renders TeX segments as <span>s with the "math" class, optionally
; with "inline" or "display" classes depending on context.
ELEMENT = span
ALLOW_ATTR = class
REGEXP = ^\s*((math(\s+|$)|inline(\s+|$)|display(\s+|$)))+

[markup.markdown]
ENABLED         = true
FILE_EXTENSIONS = .md,.markdown
RENDER_COMMAND  = pandoc -f markdown -t html --katex
```

You may redefine `ELEMENT`, `ALLOW_ATTR`, and `REGEXP` multiple times; each time all three are defined is a single policy entry. All three must be defined, but `REGEXP` may be blank to allow unconditional whitelisting of that attribute.

Once your configuration changes have been made, restart Gitea to have changes take effect.