Allow specifying custom group name when validating files from stdin

[taraspos]

Summary

When used with kustomize (as per example), produced output looks like:

 kustomize build . | conftest test -  -p policy/conftest           
FAIL - - main - Failure message

8 tests, 7 passed, 0 warnings, 1 failure, 0 exceptions

This makes it hard to locate the failure. Would be nice to have a cli flag which will allow to override the group name to some custom value instead.

[jalseth]

I'm not sure I fully understand the request. How will having the CLI print out a flag that you passed it help with locating the source of the policy violation?

[taraspos]

Let's imagine following use case, some CICD job iterates over the bunch of folders and calls kustomize on all of them:

for dir in $DIRS; do
    kustomize build $dir | conftest test -  -p $dir/policy
done

In this case failure messages will look like:

FAIL - - main - Failure message1
FAIL - - main - Failure message2
FAIL - - main - Failure message3

This doesn't give any indication which exact kustomize build violated the policy.

You could argue that just adding echo $dir command will solve the problem, however this won't work if github output format is used.

for dir in $DIRS; do
    echo $dir
    kustomize build $dir | conftest test -  -p $dir/policy -o github
done

Because produced github annotation will look something like

Job Name: -
Failure message1

Where providing some flag like conftest test - -p $dir/policy -o github --group $dir would produce useful output.

Job Name: my/component/dir
Failure message1

[jalseth]

Thanks for the context, I can see how this could be helpful in that case. PRs are welcome.