Multiple group sources support in CLI?

[thiell]

Low priority, but possible improvement when there are many group sources (we tend to have more and more group sources, currently 16 on Sherlock, 12 in yaml file + 4 external).

list groups from multiple group sources

We needed a way to list the groups where a node belongs to from group sources a, b and c

but cluset/nodeset does only support all group sources:

cluset -L node

or just a single group source:

cluset -s groupsource -l node

Currently, we need to iterate over the group sources and call cluset/nodeset multiple times.

other ideas

Example: expand group @compute from several group sources, for example:

cluset -s a,b -e @compute

Several approaches are possible here: multiline/one group source per line (I'm not a fan), or get the union of all nodes from @a:compute and @b:compute (confusing maybe?).