class ActionDispatch::ContentSecurityPolicy

def require_sri_for(*types)


policy.require_sri_for

Leave empty to not require Subresource Integrity:

policy.require_sri_for :script, :style

is required:
Specify asset types for which {Subresource Integrity}[https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity] 
def require_sri_for(*types)
  if types.first
    @directives["require-sri-for"] = types
  else
    @directives.delete("require-sri-for")
  end
end