Description of problem:

When trying to set inst.stage2=<%= medium_uri > for kickstart_kernel_custom_options on a host, the build fails:

2025-12-17T15:04:55 [W|tem|fb2c6751] Unable to build PXE kernel options: Foreman::Renderer::Scope::Macros::Base#medium_uri delegated to medium_provider.medium_uri, but medium_provider is nil

How reproducible:

100%

Is this issue a regression from an earlier version:

Unknown

Steps to Reproduce:

1. Ensure the setting "Interpolate ERB in parameters" is on (it is by default)

2. Create a host with the array parameter "inst.stage2=<%= medium_uri >" for kickstart_kernel_custom_options

Actual behavior:
Build error

2025-12-17T15:04:55 [W|tem|fb2c6751] Unable to build PXE kernel options: Foreman::Renderer::Scope::Macros::Base#medium_uri delegated to medium_provider.medium_uri, but medium_provider is nil

Expected behavior:
Host is built

To workaround this I had to edit the kickstart_kernel_options to manually place in medium_uri. I assume the interpolation somehow is happening too early. Interpolation worked when getting the medium_uri from the @host object, but it isn't allowed by safemode rendering.

Business Impact / Additional info:

I was hoping to instruct users to use this for image mode provisioning.