Render Markdown/GFM Documents online using the GitHub v3 API

Sometimes, you need to render parts of your Markdown documents – e.g. README.md or CHANGES.md – as html to embed it into your application, documentation or project website. There are a several markdown or especially GFM (GitHub Flavored Markdown) libraries are out there, but they require an additional setup and have to be maintained.

The simple Way#

Thanks to GitHub, there is a public API available which allows you to render your documents by the GitHub webservices.

PHP Client#

/**
 * Render Markdown content using the GitHub v3 Markdown API
 * @see https://developer.github.com/v3/markdown/
 * @source https://andidittrich.com/2016/05/render-markdown-gfm-documents-online-using-the-github-v3-api
 * @license: MIT
 * @return string(html)
 */
function renderGFM($text, $repositoryContext = null){

    // create the payload
    // @see https://developer.github.com/v3/markdown/
    $postdata = json_encode(
        array(
            'text' => $text,
            'mode' => ($repositoryContext != null ? 'gfm' : 'markdown'),
            'context' => $repositoryContext
        )
    );

    // prepare the HTTP 1.1 POST Request
    $opts = array('http' =>
        array(
            'method'  => 'POST',
            'protocol_version' => '1.1',
            'user_agent' => $repositoryContext,
            'header'  => array(
                'Content-type: application/x-www-form-urlencoded;charset=UTF-8',
                'Connection: close',
                'Accept: application/vnd.github.v3+json'
            ),
            'content' => $postdata
        )
    );

    // send request
    return file_get_contents('https://api.github.com/markdown', false, stream_context_create($opts));
}

Usage#

The optional $repositoryContext argument allows your to define the context which should be used for rendering to e.g. enable issue linking

// fetch the document (example)
$document = file_get_contents('https://raw.githubusercontent.com/AndiDittrich/WordPress.Enlighter/master/CHANGES.md');

// render html using the GitHub GFM API
$html = renderGFM($document, 'AndiDittrich/WordPress.Enlighter');

// show it!
echo $html;