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Parent CloudStack Environment
The Trillian framework needs to know about the environment which is it deploying into and there are some requirements for those requirements. These will be listed and explained here.
Throughout the documentation we will refer to PARENT and NESTED CloudStack environments. Confusion can occur when the two are confused, especially when it comes to networking. So to restate the obvious, The PARENT CloudStack is the environment which looks after the lifecycle of the VMs created. The NESTED environments are the ones created by Trillian.
The NESTED hypervisors must be attached to networks supplied by the PARENT CloudStack. For ease of use, the Management, guest and public networks are expected to be created as shared networks.
The NESTED guest and public networks may be on a number of different VLANs, therefore the network created in the PARENT CloudStack uses VLAN 4095 which is interpreted by the ESXi hosts as 'Trunk all VLANs from the guests'.
Isolated networks for the NESTED management planes, while great for isolation, pose an number of issues wrt to communicating with hosts which are NAT'd. Therefore we have used a shared network for management/storage
Because a number of NESTED environments must co-exist in the same IP space for public and management networks, and the same VLAN space in the case of guest networks. We carve up the available space into smaller ranges and allocate the ranges to NESTED environments on demand. And return them to the pool on tear down.
For instance, a management range of say 192.168.1.0/24 might be split into smaller chunks of 12 IP addresses each with the shared gateway of (say) 192.168.1.254
The first environment to be created would get 192.168.1.1 to 192.168.1.12 to use for its 'reserved system range' the next environment would get 192.168.1.13 to 192.168.1.24 and so on.
This is also done for Public IP addresses and guest VLANs for the NESTED environments.
These ranges are stored in a MySQL database in the PARENT CloudStack environment.
The building of VMs naturally requires the creation of templates. The template for any given VM (mgmt server, hypervisor host etc) can be set as a default in the Trillian plays, however it can be overridden in the commandline commands.
The process for creating the each of the template types is documented 'here'.