Juju client cannot bootstrap from Windows 10

[Pen Gale]

When attempting to bootstrap a Juju controller from a Windows 10 machine, using the 2.8.1 Windows client, the bootstrap fails with:

17:45:44 DEBUG juju.provider.common bootstrap.go:615 connection attempt for 52.xxx.xxx.20 failed: No RSA host key is known for 52.xxx.xxx.20 and you have requested strict checking.
Host key verification failed.

This was originally reported in the Discourse forums: https://discourse.juju.is/t/windows-client-fails-to-bootstrap-due-to-strict-host-checking-failure/3465

[Pen Gale (pengale)]

I have been able to reproduce this on a Windows 10 box.

The CI tests for the Windows client aren't failing, so I went ahead and tried on a Windows 2012 Server. This seemed to work fine -- the failure appears to be a different between the Windows products that we're testing on, and the typical Windows desktop setup. I'll post repro steps shortly.

[Pen Gale (pengale)]

To reproduce:

Launch Windows and open a PowerShell session. Run the following:

    $url = "https://launchpad.net/juju/2.8/2.8.1/+download/juju-setup-2.8.1-signed.exe"
    $output = "juju_installer.exe"

    $wc = New-Object System.Net.WebClient
    $wc.DownloadFile($url, $output)

    .\juju_installer.exe

Exit and restart the PowerShell session to refresh the path (there's probably a better way to do this -- my PowerShell fu is not strong), then run:

    juju add-credential aws # follow prompts
    juju bootstrap aws aws

This process success on Windows Server 2012, which I believe is what we're running for CI. It fails on Windows 10, as noted above.

[Pen Gale (pengale)]

Whoops. In the repro steps above, make sure to run juju bootstrap with --debug, so that you can see the error when it first occurs, rather than waiting for juju to give up retrying :-)

[Pascal Hobus (pascalhobus)]

I can confirm that this issue is also existing for the following comibination:
OS: Windows 10 Pro, Build 20H2
Juju-Windows-Client: juju-2.9-rc8