Implement a simple NetworkPolicy for infra by default

[bowei]

It is one of the goals of this project to provide a solution for integration of rich L7 network policies on the Actors, but we should start off with a capability to have at least basic egress controls relevant to sandboxes:

• Actors should not be able to talk to things by default.
• (Optional) Actors may able to egress out of the cluster e.g. the Internet.

Clearly this is a vast simplification of what we should support, but would be a good starting point towards having a secure default.

Note: this is for INFRA -- as a belts suspenders approach. Actor-specific enforcement will happen on a different layer.

[thockin]

Related to or dup of #126?

#126 is about egress, but I think we need something to express peer-to-peer?

[mikemorris]

Not a dupe IMO, #126 is focused exclusively on (Optional) Actors may able to egress out of the cluster e.g. the Internet. and supplemental capabilities (credential injection) to facilitate that. I'm assuming "transparent redirection" capabilities to ensure off-cluster traffic is routed to an appropriate egress should be under the scope of #126 too.

Suggest dropping that from the scope here and narrowing focus to Actors should not be able to talk to things by default.

Can we also clarify if this is intended to be a design issue (create some new Substrate-specific networking policy?) and if identity-based AuthZ is a design expectation (therefore blocked by #124).

The title could be confused with something like implementing a Kubernetes NetworkPolicy for the control plane components rather than focused on actor capabilities?

Note: this is for INFRA -- as a belts suspenders approach. Actor-specific enforcement will happen on a different layer.