fix: powershell does not support $? operator, or # for comments

[troyfactor4]

Issue #, if available:

No issue, but I can create one if necessary.

Description of changes:

cfn-signal fails to execute as powershell does not recognise "$?" and instead on Windows we need to use "$LASTEXITCODE". The error given in the logs is: "cfn-signal: error: option -e: invalid integer value: '$?'"

Also starting a command with "#" will also fail. This seems like it was intended to be a comment in the logs, so used "echo" instead.

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[dbaileyut]

I think the $? vs $LASTEXITCODE change is necessary.
Updating the # comment to echo is fine but, I don't see anything wrong with # - that's a valid comment in PowerShell.

[troyfactor4]

The problem with the "#" is the way its being used is it is trying to execute a program called "#". If you look at the log files, something akin to "The application '#' cannot be found" is displayed. Now, it doesn't stop execution of the script but you get a bunch of unnecessary warning messages. Using "echo" achieves the intended purpose.

[dbaileyut]

Actually, is it even running PowerShell... it's <script>...</script> not <powershell>...</powershell>

[lorengordon]

Actually, is it even running PowerShell... it's <script>...</script> not <powershell>...</powershell>

I think the changeset is correct, but the explanation is off. cmd shell does not support $? or # comments. But powershell does. The change is compatible with cmd shell.

[dbaileyut]

$LASTEXITCODE won't work in cmd shell - you want %ERRORLEVEL% for cmd

[troyfactor4]

I don't have a background in Windows servers, so I don't know if its cmd or powershell, but I can say that I (painstakingly) took the time to deploy the LZA multiple times to arrive at this pull request and the values I suggest provide working and clean output. %ERRORLEVEL% may also work, I have no idea, but I can also guarantee you from actually deploying it that $LASTEXITCODE does indeed work.

[dbaileyut]

I've got a pretty strong Windows background. $LASTEXITCODE won't error but doesn't do what's intended if cfn-init.exe fails. %ERRORLEVEL% is definitely what was intended. I'd suggest opening a GitHub issue and or AWS support case since this PR hasn't gotten picked up. I would, but I'm not using DirectoryServices and just came across this looking for duplicates on a different issue,

[troyfactor4]

Got it. Thanks for the clarification @dbaileyut ! That makes sense.