I’ll try to explain the issue with an example, and a few questions which highlight the issues. I’ll do my best to stick to the actual terminology from MS:
Let’s say you have a Windows cluster comprised of two nodes (physical machines). On each node, you have 2 groups, which are themselves comprised of: a Generic Service resource, a Physical Disk resource, an IP Address resource, and a DNS Name resource. Note that none of these groups are duplicates or copies of each other: they each represent distinct services to be deployed.
Also assume that each of these groups correspond to different Octopus Deploy roles. In other words, they will be deployed by different Octopus Deploy processes/projects.
Any of these groups can be on either node at any time.
If I follow your suggestion, and basically configure both nodes with the same Octopus configuration, that means that Octopus only sees one entity, as you correctly pointed out. This is a problem, though, since then the question is: which node will receive the actual deployment? Since each group has its own IP: which IP will be used for the Tentacle communication?
Reading your response, it seems that your assumption is that we will only have one cluster resource group. Of course, the described solution would work for that case, since the Tentacle moves with the one and only resource group. Once another cluster group is added, which can be on a separate node from the other one, the solution falls apart (since Octopus itself won’t let you have two installations (exe’s) on the same node). In fact, this is exactly what we attempted, and the solution didn’t work for us.
EDIT: As I am rereading, I see your earlier comment: “If you want to do this for multiple cluster resource groups, you have to install multiple (side-by-site) tentacles, one for each resource group, all of which have to appear as separate tentacles to the Octopus server.” So it seems we are in complete agreement, EXCEPT that the actual installation of side-by-side tentacles is not possible due to the way that the Tentacles register themselves on the server. If there is a way to do this (supported by Octopus), please send details, and we can try this.