Scalr requires specific networking configuration for OpenStack. Specifically, both Scalr and the Scalr Agent ("Scalarizr") need to be able to reach the API ports for a certain number of OpenStack services.
Those ports should therefore be available for access by your Scalr Host, and by the instances it is managing.
Your OpenStack installation may make those services available on a non-default port. To find out the exact port for your installation, use the following CLI command:
Note: All ports to be opened will be TCP and only need to be open in one direction, Scalr Server > OpenStack and Scalarizr Agent > OpenStack.