landscape bundle error when deployed via gui (KeyError in config changed hook in haproxy charm)

[anastasiamac]

From https://bugs.launchpad.net/juju/+bug/1651260:

I ran into this bug while testing matrix, but it also seems to affect the gui.

Here's how to reproduce it:

1. Setup a model on aws, and fire up the gui.
2. Add the "Landscape Dense-Mass" bundle to the canvas (https://54.159.236.52:17070/gui/b13bbd14-2a27-4fbf-827e-35116de20180/?store=cs:bundle/landscape-dense-maas-1)
3. Commit, and wait for the deploy to settle.
4. Note that haproxy is in an errored state. Inspecting the logs, you will see a KeyError fetching the "services" key from the config during the config changed hook.

The error does not occur when one deploys the landscape bundle via the command line client. This bug possibly occurs because the haproxy charm is fairly old; updating the charmhelpers in that bundle might fix it. It would be nice to fix this in the gui (and in matrix!), though, as the juju client seems to be working around the bug, and other charms and bundles might break because of it.

Note that the "services" option is specified as a blank string in the bundle.yaml; it is possible that the juju client is doing something special with falsey values which the gui is not.

I'm filing this here because I suspect that we're running into some undocumented behavior on the part of core or the client, and I'd like to get some information about the fix here, before I attempt to apply the fix to matrix/python-libjuju, or file a bug with the gui.

(All this happens in a freshly bootstrapped controller, on aws, under juju 2.1 beta3.)

[hatched]

Thanks for the report @anastasiamac