homelab/hivemind
1
0
Fork 0
Code Activity
hivemind/TODO.md

2.4 KiB
Raw Blame History

Background

Some background first: the node can have multiple roles this includes (but not limited to)

  • Host (can generate events)
  • DNS (can consume the events and act on them)
  • Something else that I might come up with (the architecture has to be expandable)

Control pane (3+ nodes)

  • Quorum
    • Consists of n / 2 + 1 nodes
    • Cluster is considered "degraded" if no quorum can be created
  • Stores an event log
    • Only leader can append to the log (with quorum permission)
  • Membership authority
    • No joins without quorum approval
    • Leaves are not propagated without quorum
  • Manages epoch (useful for GC)
    • Node N with N.epoch != cluster.epoch can not join the cluster, and has to re-join (bootstrap)
  • Can (but doesn't have to) be a bootstrap point

Membership

  • Membership is managed though SWIM
  • Each node contains a small slice of the entire network

Joining

Each node has an array of roles:

  1. That it performs
  2. That it requires to operate (can be moved out to the master, or the shared type)
  3. That it needs for bootstrapping (analogous to 2.)

Node can join via a master or via other nodes When a node requests to join, the responder makes a request to the CP and asks for a permission to add this node

  • If master allows
    1. The node gets a membership digest from the CP.
    2. The node can be brought up to speed using it's neighbors from 1.
    3. Node join event gets broadcasted over SWIM gossiping
  • Otherwise, nothing happens

Host node

Bootstrap

Host node requests dns nodes on join (and other node types, such as ns, nginx, etc... They should really be called something like dns_processor, and the internals (how it processes the dns) should not be visible to the cluster, but that's a task for a future me) When a new update occurs, it sends the update to some dns hosts.

DNS node

Bootstrap

First, it gets all the available hosts from the CP Then it requests their configs and sets map[hostName]seq accordingly

Simple join (when other nodes exist)

It requests it's config from other nodes and that's it

Minor To-Do

  • auth middleware lol
  • move request logging out of the request handling into a middleware
  • nginx role
  • think about choosing the master for the keepalive message (should be somewhat load-balanced)
  • hivemind lite should not just print hivemind-lite lol
  • different transport (maybe something like a custom binary protocol)