Naming distributed nodes

[bkolobara]

We should be able to name distributed nodes to easier differentiate them. This would also include host function for looking up nodes by name and returning names when getting all nodes.

[kosticmarin]

@withtypes and me were discussing this, here is what we propose to do.

We add a new CLI flag which will accept key=value pairs (this would be a repeated flag), e.g. --tag name=worker01 --tag group=workers.

Then we can add a simple query syntax for looking up nodes by tags. e.g.

let nodes = lunatic::distributed::lookup_nodes("key=group^value=workers");

In the first iteration we would start simple with syntax like "key=k1^value=v1" and "key=k1^value=v1,v2,v3", then later we can expand. Syntax is also something we can discuss further, perhaps we can define a better Postfix syntax which would be easier to parse with more complex queries.

This would allow us to differentiate nodes not just by names but by any user defined values.

[bkolobara]

I like it!

Is the argument to lookup_nodes treated as a filter? For example, would calling lookup_nodes("") return all known nodes? But then you could narrow it down: lookup_nodes("name=specific").

Would all nodes contain a list of their peers or would this lookup be done on the control node?

[kosticmarin]

lookup_nodes would take 'static str, control node would parse the expression and return results.

lookup_nodes("name=specific")

Narrowing down the looks better I agree!