Jupsen is a tool that allows you to drop or delay packets between juju units.

Why is this useful?

Network problems happen, if you’re working on a distributed system you need to deal with them, this is much easier to do if you’re able to recreate these situations easily.

With jupsen you can

• Block traffic between two units in only one direction
• Block traffic between two units in only both directions
• Delay packets in one direction
• Delay packets in both directions.

This can be used to recreate some of the experiments in Kyle Kingsbury’s jupsen series (from which I have shamefully taken the name) (https://aphyr.com/tags/jepsen)

If you want to have a play around with jupsen you can get it here: (https://github.com/mattyw/jupsen)

If you want to see it in action you can take a look at this demo I gave at the recent Ubuntu Online Summit.