Pass custom header in signing request

[karthik-murugan-hpe]

Name of feature: Custom headers in signing request

Pain or issue this feature alleviates: Custom authentication of Signing Requests is not possible today, because there's no mechanism to include a token or credential in the request

Why is this important to the project (if not answered above):

Is there documentation on how to use this feature? If so, where? Added a section to README

In what environments or workflows is this feature supported? Leveraging this feature also requires a gateway in front of the step-ca to authenticate based on the header.

In what environments or workflows is this feature explicitly NOT supported (if any)? As mentioned above, this feature requires an authentication mechanism implemented in front of step-ca

Supporting links/other PRs/issues:

💔Thank you!#

[CLAassistant]

All committers have signed the CLA.

[tashian]

hi @karthik-murugan-hpe, thanks for creating this PR.
Upon review, we can't commit to merging this right now because it adds a lot of new code that we don't have the capacity to maintain in open source.

However, it's possible for us to assign priority for our customers.
If this is a feature you are using in production at HPE, and you want to discuss a commercial agreement, let's connect for a video call.

[karthik-murugan-hpe]

Hi @tashian, there were too many such extensions needed to fit our usecase and we ended up developing our own issuer. Thank you.