HA for MaxScale CDC (Active/Passive Automated)

Today, HA deployments run two MaxScale nodes with cooperative monitoring and cluster config sync. Both nodes' binlogrouters need to stay running so binlogs exist to be replayed into Exasol.

However, if the CDC pipeline runs active on both nodes simultaneously, Exasol receives duplicate writes. One MaxScale must be passive for CDC while both binlogrouters stay active.

Ask: Define and implement active/passive CDC behavior across the two MaxScale nodes, so only one node replays into Exasol at a time, while binlogrouter replication continues on both for failover readiness.

Acceptance Criteria:

• Only one MaxScale node actively replays CDC into Exasol at any time; the other stays passive.
• Both nodes' binlogrouters remain running and replicating, regardless of CDC active/passive state. (interesting if shared storage could be used to deduplicate the binlogs and share state/ separate disk from compute)
• Passive/active CDC role is derived from cooperative monitoring state or similar (i.e., follows which node is primary), not manually configured.
• On failover, the newly primary MaxScale becomes CDC-active without manual intervention.
• No duplicate writes to Exasol occur during normal operation or during a failover transition.
• No data loss or gap in replayed binlog events during failover (CDC resumes from correct position).