Quickly patching a failing Ansible setup

In my network, I use Ansible to configure both servers and clients. And yes, that includes Windows clients too. And it all worked flawlessly for a while. Out of nowhere, one Wednesday, my wife's Surface Pro started failing its Ansible setup steps with Error when collecting bios facts.

For example:

[WARNING]: Error when collecting bios facts: New-Object : Exception calling ".ctor" with "0" argument(s): "String was not recognized as a valid DateTime."  At line:2 char:21  + ...         $bios = New-Object -TypeName
Ansible.Windows.Setup.SMBIOSInfo  +                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~      + CategoryInfo          : InvalidOperation: (:) [New-Object], MethodInvocationException      +
FullyQualifiedErrorId : ConstructorInvokedThrowException,Microsoft.PowerShell.Commands.NewObjectCommand      at <ScriptBlock>, <No file>: line 2

And yes, the full list of exceptions was a bit longer, but they all had one thing in common. They were pointing toward SMBIOSInfo.

The first order of business was to find what the heck was being executed on my wife's Windows machine. It took some process snooping to figure out that setup.ps1 was the culprit. Interestingly, this was despite ansible_shell_type being set to cmd. :)

On my file system, I found that file at two places. However, you'll notice that if you delete one in the .ansible directory, it will be recreated from the one in /usr/lib.

/usr/lib/python3/dist-packages/ansible_collections/ansible/windows/plugins/modules/setup.ps1
/root/.ansible/collections/ansible_collections/ansible/windows/plugins/modules/setup.ps1

Finally, I was ready to check the script for errors, and it didn't take me long to find the one causing all the kerfuffle I was experiencing.

The issue was with the following code:

string dateFormat = date.Length == 10 ? "MM/dd/yyyy" : "MM/dd/yy";
DateTime rawDateTime = DateTime.ParseExact(date, dateFormat, null);
return DateTime.SpecifyKind(rawDateTime, DateTimeKind.Utc);

That code boldly assumed the BIOS date uses a slash / as a separator. And that is true most of the time, but my wife's laptop reported its date as 05.07.2014. Yep, those are dots you're seeing. Even worse, the date was probably in DD.MM.YYYY format, albeit that's a bit tricky to prove conclusively. In any case, ParseExact was throwing the exception.

My first reaction was to simply return null from that function and not even bother parsing the BIOS date as I didn't use it. But then I opted to just prevent the exception as maybe that information would come in handy one day. So I added a TryParse wrapper around it.

DateTime rawDateTime;
if (DateTime.TryParseExact(date, dateFormat, null,
    System.Globalization.DateTimeStyles.None, out rawDateTime)) {
    return DateTime.SpecifyKind(rawDateTime, DateTimeKind.Utc);
} else {
    return null;
}

This code retains status quo. If it finds the date in either MM/dd/yyyy or MM/dd/yy format, it will parse it correctly. Any other format will simply return null, which is handled elsewhere in the code.

With this change, my wife's laptop came back into the fold, and we lived happily ever after. The end.

PS: Yes, I have opened a pull request for the issue.

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