Powershell modules, json conversion quirk

Archives Ansible Developer
1

I came across this powershell quirk today and thought I should share it with anyone else who might be writing powershell ansible modules.

It seems there is a bug, or at least an inconsistency in the behaviour of ConvertTo-Json

It appears that it fails to convert strings to json if they end with a trailing backslash, which is a hazard for windows folder paths which can be expressed with a trailing backslash, e.g c:\temp\

What is strange is that if you use the -Compress option with ConvertTo-Json the string seems to convert ok.

I wound up using

$message = $message.TrimEnd("") to clean up the affected string in my custom module, but I’m considering whether it would be wise to add -Compress to the two places it occurs in lib/ansible/module_utils/powershell.ps1. This would make ansible a bit more robust to modules without sanitized output - I suppose at the expense of the overhead of ‘compressing’ the json (which seems to just be quoting and removing whitespace).

The issue is described here:

https://connect.microsoft.com/PowerShell/feedback/details/869768/powershell-convertto-json-error-when-has-string-with-trailing-backslash

All the best,

Jon

2

i would be fine with always compressing the json, most of the time we
reformat the output at the ansible command line anyways.

3

We use the -Compress option for some of our custom modules and we have not have issues for now.

+1 for making it by default so that trailing backslash and some other issues are fixed.

4

Ok. I was about to create PR to make the change but noticed that
version of module_utils/powershell.ps1 in v2 is older than the v1 code.

I’m thinking perhaps best to leave this until v2 is current.

Jon

5

files seem to be the same now, feel free to update one and we'll make
sure changes percolate to the other.

6

Will do

7

Still seems to be a small difference to me (different checksum algorithm being used), but I have pushed to the ‘v1’ version PR is https://github.com/ansible/ansible/pull/11090

Jon