Previewer

Previewer is a quick hack around Mattermost’s inability to show previews for links other than images and YouTube videos. It’s like a proxy for your links: it acts as an image for Mattermost but will redirect any “normal” user to the original link.

Run

Previewer requires Python 3.x. Install its dependencies:

pip install -r requirements.txt

Then run the app:

gunicorn app:app

Check gunicorn’s options for ports and more. There’s also Procfile and runtime.txt files for quick deployment on Heroku & friends (I use Flynn).

Usage

You have to build URLs by hand for now. Prepend <your previewer hostname> to your URL, and append /p.png at its end. Be careful that if your original URLs has parameter you need to put the /p.png before them.

Examples

In the examples below we assume you deployed your instance at http://p.example.com:

• https://www.google.com -> http://p.example.com/https://www.google.com/p.png
• https://www.youtube.com/watch?v=Sagg08DrO5U -> http://p.example.com/https://www.youtube.com/watch/p.png?v=Sagg08DrO5U
• https://news.ycombinator.com/item?id=14068363 -> http://p.example.com/https://news.ycombinator.com/item/p.png?id=14068363

How it works.

See my blog post.