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configuration-raft.md

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Configuration: raft

Set up a orchestrator/raft cluster for high availability.

Assuming you will run orchestrator/raft on a 3 node setup, you will configure this on each node:

  "RaftEnabled": true,
  "RaftDataDir": "<path.to.orchestrator.data.directory>",
  "RaftBind": "<ip.or.fqdn.of.this.orchestrator.node>",
  "DefaultRaftPort": 10008,
  "RaftNodes": [
    "<ip.or.fqdn.of.orchestrator.node1>",
    "<ip.or.fqdn.of.orchestrator.node2>",
    "<ip.or.fqdn.of.orchestrator.node3>"
  ],

Some breakdown:

  • RaftEnabled must be set to true, otherwise orchestrator runs in shared-backend mode.
  • RaftDataDir must be set to a directory writable to orchestrator. orchestrator will attempt to create the directory if not exists.
  • RaftBind must be set, use the IP address or full hostname of local host. This IP or hostname will also be listed as one of the RaftNodes variable.
  • DefaultRaftPort can be set to any port, but must be consistent across all deployments.
  • RaftNodes should list all nodes of the raft cluster. This list will consist of either IP addresses or host names, and will include the value of this host itself as presented in RaftBind.

As example, the following might be a working setup:

  "RaftEnabled": true,
  "RaftDataDir": "/var/lib/orchestrator",
  "RaftBind": "10.0.0.2",
  "DefaultRaftPort": 10008,
  "RaftNodes": [
    "10.0.0.1",
    "10.0.0.2",
    "10.0.0.3"
  ],

as well as this:

  "RaftEnabled": true,
  "RaftDataDir": "/var/lib/orchestrator",
  "RaftBind": "node-full-hostname-2.here.com",
  "DefaultRaftPort": 10008,
  "RaftNodes": [
    "node-full-hostname-1.here.com",
    "node-full-hostname-2.here.com",
    "node-full-hostname-3.here.com"
  ],

NAT, firewalls, routing

If your orchestrator/raft nodes need to communicate via NAT gateways, you can additionally set:

  • "RaftAdvertise": "<ip.or.fqdn.visible.to.other.nodes>"

to IP or hostname which other nodes should contact. Otherwise other nodes would try to talk to the "RaftBind" address and fail.

Raft nodes will reverse proxy HTTP requests to the leader. orchestrator will attempt to heuristically compute the leader's URL to which redirect requests. If behind NAT, rerouting ports etc., orchestrator may not be able to compute that URL. You may configure:

  • "HTTPAdvertise": "scheme://hostname:port"

to explicitly specify where a node, assuming it were the leader, would be accessed through HTTP API. As example, you would: "HTTPAdvertise": "http://my.public.hostname:3000"

Backend DB

A raft setup supports either MySQL or SQLite backend DB. See backend configuration for either. Read high-availability page for scenarios, possibilities and reasons to using either.

Single raft node setups

In production, you will want using multiple raft nodes, such as 3 or 5.

In a testing environment you may run a orchestrator/raft setup composed of a single node. This node will implicitly be the leader, and will advertise raft messages to itself.

To run a single-node orchestrator/raft, configure an empty RaftNodes:

  "RaftNodes": [],

or, alternatively, specify a single node, which is identical to RaftBind or RaftAdvertise:

  "RaftEnabled": true,
  "RaftBind": "127.0.0.1",
  "DefaultRaftPort": 10008,
  "RaftNodes": [
    "127.0.0.1"
  ],