Bootstrapping continues after being interrupted

[Jordan Barrett]

On Juju 2.9-latest, if you interrupt `juju bootstrap` with a Ctrl-C, it says that it's "stopping bootstrap", yet it continues the process:
```
$ juju bootstrap localhost foo2
Creating Juju controller "foo2" on localhost/localhost
Looking for packaged Juju agent version 2.9.29 for amd64
^C
Ctrl-C pressed, stopping bootstrap and cleaning up resources
No packaged binary found, preparing local Juju agent binary
To configure your system to better support LXD containers, please see: https://github.com/lxc/lxd/blob/master/doc/production-setup.md
Launching controller instance(s) on localhost/localhost...
 - juju-78b160-0 (arch=amd64)
Installing Juju agent on bootstrap instance
Fetching Juju Dashboard 0.8.1
Waiting for address
ERROR failed to bootstrap model: cancelled
```

If you interrupt it late enough, it actually still creates the controller:
```
$ juju bootstrap localhost foo2
Creating Juju controller "foo2" ...
...
Running machine configuration script...
^C
Ctrl-C pressed, stopping bootstrap and cleaning up resources
Bootstrap agent now started
Contacting Juju controller at 10.228.51.139 to verify accessibility...
Initial model "default" added

$ juju controllers
Controller ...
foo2* ...
```

This new controller is completely broken - if you try to do anything with it (deploy, add-model, even status), it just hangs forever.

[Vitaly Antonenko (anvial)]

Hi Jordan,

Can you more in detail describe the moment when you catch this issue.

I try to ^C while 'Running machine configuration script...', but cannot reproduce the bug. Here is my paste:

https://pastebin.ubuntu.com/p/gFXNbyK8nh/

[Jordan Barrett (barrettj12)]

@anvial: the issue is apparent in the first log, where even after pressing Ctrl-C, it continues with the bootstrapping steps:
```
Launching controller instance(s) on localhost/localhost...
 - juju-6b8de5-0 (arch=amd64)
Installing Juju agent on bootstrap instance
Fetching Juju Dashboard 0.8.1
...
```

I just tried to reproduce on 2.9.30 and observed the same behaviour. I'm pressing Ctrl-C immediately after Juju prints `Running machine configuration script...`.

https://pastebin.ubuntu.com/p/rRv2T2f2Mx/

This is Juju v2.9.30-82fdde7 on Ubuntu 20.04 LTS. Maybe you and I have different LXD configurations?

[Jordan Barrett (barrettj12)]

I'm still noticing this bug on both Juju 2.9 and 3.0, and on multiple clouds. Here's an example from just today, with Juju 3.0 and AWS:
------------------------------------------------------------
$ juju bootstrap aws
Creating Juju controller "aws-us-east-1" on aws/us-east-1
^C
Ctrl-C pressed, stopping bootstrap and cleaning up resources
Looking for packaged Juju agent version 2.9.35 for amd64
Located Juju agent version 2.9.35-ubuntu-amd64 at https://juju-dist-aws.s3.amazonaws.com/agents/agent/2.9.35/juju-2.9.35-linux-amd64.tgz
Launching controller instance(s) on aws/us-east-1...
 - i-0710a33555e8e58d4 (arch=amd64 mem=8G cores=2)
Installing Juju agent on bootstrap instance
Fetching Juju Dashboard 0.8.1
Waiting for address
ERROR failed to bootstrap model: cancelled
------------------------------------------------------------

[Simon Richardson (simonrichardson)]

PR: https://github.com/juju/juju/pull/15531