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Jupsen: Modelling Networking Partitions With Juju

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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) (

If you want to have a play around with jupsen you can get it here: (

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