Juju Black Magic

As part of my general readings, I came across an interesting tool called Juju. It’s developed by Canonical and my best attempt at describing is that it is a macro-infrastructure provisioning tool. But my initial experience was poor because their tutorial simply didn’t work out of the box.

Juju is designed to quickly build up a large-scale deployment, such as a Hadoop or Kubernetes cluster. It also supports scaling the deployment after the fact with some simple commands. It’s a nice idea for sure.

Testing it out is supported with LXD, a Linux service that works with LXC containers and is comparable to it’s far more popular cousin, Docker. The downside of using LXD is that the community is far smaller and common problems not well documented.

I tried following the local cloud tutorial in the Juju docs and hit a number of roadblocks. As illustration of how inaccurate the tutorial is, this is the verbatim command history from my shell:

sudo snap install juju
sudo snap install lxd
/snap/bin/lxd init
/snap/bin/lxc network edit lxdbr0
>> config:
>>   ipv6.address: none
>>   ipv6.nat: "false"
sudo ufw disable
/snap/bin/juju bootstrap localhost lxd-test

A few points of explanation:

• Note the use of /snap/bin as a prefix otherwise your shell won’t find the binaries by default. Unless you run them as sudo, but this can lead to it’s own issues.
• The default bridge LXD generates adds IPv6 support, but this is not supported by Juju and the bootstrap immediately errors unless you disable IPv6.
• The local firewall had to be disabled because Juju’s controller is blocked from accessing the host LXD API otherwise. I haven’t determined the precise rule needed to enable this because there is 0 documentation around the controller requirements (in the tutorial at least). UPDATE: it seems like only port 8443 needs to be opened.

I got there eventually, but I very nearly gave up a number of times. Only the promise of what Juju offers kept me going. Plus, my personal motto is “Never give up, never surrender”.