Summary

Make all quorum queue Ra configuration parameters explicit and configurable via rabbitmq.conf.

This PR expands on the initial work to make segment sizing configurable by exposing all quorum queue Ra system parameters through the quorum_queue.* configuration namespace. This allows operators to fine-tune Raft log and WAL behavior specifically for quorum queues, with backward compatibility for the legacy raft.* configuration options.

Motivation

Previously, quorum queue Ra system parameters could only be configured via the global raft.* settings or the pre-launch default configuration. This PR provides dedicated quorum_queue.* configuration options that:

1. Make the configuration flow explicit and discoverable
2. Allow quorum queue-specific tuning without affecting other Ra-based systems (Khepri, streams)
3. Maintain backward compatibility with existing raft.* configurations
4. Centralize defaults in one place for easier maintenance

Changes

New quorum_queue.* Configuration Options

• quorum_queue.segment_max_size_bytes (default: 64 MB)
• quorum_queue.segment_max_entries (default: 4096)
• quorum_queue.wal_max_size_bytes (default: 512 MB)
• quorum_queue.wal_max_entries (default: 500,000)
• quorum_queue.wal_max_batch_size (default: 4096)
• quorum_queue.wal_compute_checksums (default: true)
• quorum_queue.segment_compute_checksums (default: true)
• quorum_queue.max_append_entries_rpc_batch_size (default: 16)
• quorum_queue.compress_mem_tables (default: true)
• quorum_queue.snapshot_chunk_size (default: 1 MB)

Implementation Details

1. Schema Mappings: Added Cuttlefish schema mappings for each quorum_queue.* setting that map to rabbit application environment variables
2. Backward Compatibility: Each quorum_queue.* setting falls back to the corresponding raft.* setting if not explicitly configured
3. Explicit Configuration: All parameters are explicitly passed to the quorum_queues Ra system configuration during initialization, making the data flow transparent
4. Defaults Alignment: All default values match the RabbitMQ prelaunch defaults, ensuring consistent behavior
5. Code Simplification: Simplified WalMaxEntries handling to use application:get_env with macro defaults instead of complex case statement logic

Files Changed

• deps/rabbit/src/rabbit_ra_systems.erl: Updated to read quorum_queue configuration and apply defaults via macros
• deps/rabbit/priv/schema/rabbit.schema: Added mappings and translations for all quorum_queue.* settings
• deps/rabbit/docs/rabbitmq.conf.example: Documented all new configuration options
• deps/rabbit/test/config_schema_SUITE_data/rabbit.snippets: Added test coverage for all new settings

Test Plan

• Configuration schema tests verify all mappings parse correctly
• Default values align with Ra's built-in defaults
• Backward compatibility verified via fallback to raft.* settings
• Build compiles successfully without linter errors

Notes

• All defaults match the values previously set in rabbit_prelaunch_conf.erl
• Configuration is centralized via macros for easier future maintenance
• No breaking changes; existing configurations continue to work unchanged

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  This is an automatic backport of pull request Improve quorum queue Ra system configurability #15962 done by Mergify.