cmd to join new computes

[j0hnL]

Is your feature request related to a problem? Please describe.
we need a command to join new computes after the cluster has been created.

Describe the solution you'd like
something like grow_cluster -f ./new_inventory_file

Describe alternatives you've considered
maybe just a tag in the ansible playbook?

Additional context
this could apply to different scenarios:

1. adding new compute hardware to existing cluster
2. adding cloud infrastructure to existing cluster

[lwilson]

Definitely a needed feature. I think the right approach might be to make startworkers the place where this happens, i.e., startworkers is really just grow_cluster beyond a cluster of 1 node.

[lwilson]

If we are considering the refactoring task that's being discussed in #139, then we could have multiple main playbooks for these different operations within the omnia namespace:

omnia.create     # Create a cluster
omnia.destroy    # Tear-down a cluster
omnia.grow       # Add nodes to a cluster
omnia.shrink     # Remove nodes from a cluster

So omnia.grow might accept an inventory file where the manager is already operational, but compute hosts need to be added. Similarly, omnia.shrink might accept an inventory file where the manager is already operational, but compute hosts need to be removed.

omnia.create is basically the omnia.yml proposed in #139, while omnia.destroy is a playbook-based version of scuttle (see #83).

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[lwilson]

Commenting to prevent this issue from being closed. I think this is a really important capability that we should continue to develop.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.