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Cluster Relay

A relay is typically installed on a third site to provide two services to clusters:

  • Act as a key-value store for relay-type heartbeats to exchange their encrypted datasets using different network paths.
  • Act as a voter in quorum votations.

Compatibility

A relay is a simple standalone OpenSVC server.

  • A v2 server can serve as a relay for v2 clusters
  • A v3 server can serve as a relay for v3 clusters.
  • A v2 server can not serve as relay for v3 clusters
  • A v3 server can not serve as relay for v2 clusters

Changes:

  • The v2 server relay API handlers require the cluster nodes communicate with the relay node secret, granting root privilege.
  • The v3 server relay API handlers require the cluster nodes communicate with a user account with the heartbeat privilege.
  • The v3 server relay API handlers store the cluster nodes datasets in per-user namespaces, so a single relay can serve multiple client populations.

Configure a v3 relay server

Install the opensvc-server package, then create the user account the clusters will use:

om system/usr/relay create --kw grant=heartbeat

Set a password for the user. Example with a random generated password:

om system/usr/relay key add --name=password --from /dev/urandom
om system/usr/relay key decode --name=password

➡️ See Also