Poor Host Factory Performance with Many Hosts

[micahlee]

When a host factory is used to create many hosts (> 1000), the performance of host creation begins to degrade significantly.

This stems from the layers retrieval for the host factory:

conjur/app/controllers/host_factories_controller.rb

Line 29 in e336a1d

role.layers,

This method retrieves all of layer objects the host factory is a member of, in order to add created host objects to these same layers. However, this filter is implemented as Ruby code, rather than through SQL:

conjur/app/models/role.rb

Lines 129 to 133 in e336a1d

	def layers
	memberships_as_member.select do |membership|
	membership.role.kind == "layer"
	end.map(&:role)
	end

This leads to performance issues because the host factory is a "member of" each host it creates, by nature of being the owner. This means that each host is loaded from the database in order to apply the filter against it (membership.role.kind == "layer").

This layer filter should instead be implemented as SQL query returning only the layer memberships directly from the database.