package envoy.extensions.load_balancing_policies.ring_hash.v3

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This configuration allows the built-in RING_HASH LB policy to be configured via the LB policy extension point. See the :ref:`load balancing architecture overview <arch_overview_load_balancing_types>` for more information. [#next-free-field: 8]

• RingHash.HashFunction hash_function = 1

  The hash function used to hash hosts onto the ketama ring. The value defaults to :ref:`XX_HASH<envoy_v3_api_enum_value_config.cluster.v3.Cluster.RingHashLbConfig.HashFunction.XX_HASH>`.

• optional google.protobuf.UInt64Value minimum_ring_size = 2

  Minimum hash ring size. The larger the ring is (that is, the more hashes there are for each provided host) the better the request distribution will reflect the desired weights. Defaults to 1024 entries, and limited to 8M entries. See also :ref:`maximum_ring_size<envoy_v3_api_field_config.cluster.v3.Cluster.RingHashLbConfig.maximum_ring_size>`.

• optional google.protobuf.UInt64Value maximum_ring_size = 3

  Maximum hash ring size. Defaults to 8M entries, and limited to 8M entries, but can be lowered to further constrain resource use. See also :ref:`minimum_ring_size<envoy_v3_api_field_config.cluster.v3.Cluster.RingHashLbConfig.minimum_ring_size>`.

• bool use_hostname_for_hashing = 4

  If set to ``true``, the cluster will use hostname instead of the resolved address as the key to consistently hash to an upstream host. Only valid for StrictDNS clusters with hostnames which resolve to a single IP address. .. note:: This is deprecated and please use :ref:`consistent_hashing_lb_config <envoy_v3_api_field_extensions.load_balancing_policies.ring_hash.v3.RingHash.consistent_hashing_lb_config>` instead.

• optional google.protobuf.UInt32Value hash_balance_factor = 5

  Configures percentage of average cluster load to bound per upstream host. For example, with a value of 150 no upstream host will get a load more than 1.5 times the average load of all the hosts in the cluster. If not specified, the load is not bounded for any upstream host. Typical value for this parameter is between 120 and 200. Minimum is 100. This is implemented based on the method described in the paper https://arxiv.org/abs/1608.01350. For the specified ``hash_balance_factor``, requests to any upstream host are capped at ``hash_balance_factor/100`` times the average number of requests across the cluster. When a request arrives for an upstream host that is currently serving at its max capacity, linear probing is used to identify an eligible host. Further, the linear probe is implemented using a random jump in hosts ring/table to identify the eligible host (this technique is as described in the paper https://arxiv.org/abs/1908.08762 - the random jump avoids the cascading overflow effect when choosing the next host in the ring/table). If weights are specified on the hosts, they are respected. This is an O(N) algorithm, unlike other load balancers. Using a lower ``hash_balance_factor`` results in more hosts being probed, so use a higher value if you require better performance. .. note:: This is deprecated and please use :ref:`consistent_hashing_lb_config <envoy_v3_api_field_extensions.load_balancing_policies.ring_hash.v3.RingHash.consistent_hashing_lb_config>` instead.

• optional common.v3.ConsistentHashingLbConfig consistent_hashing_lb_config = 6

  Common configuration for hashing-based load balancing policies.

• optional common.v3.LocalityLbConfig.LocalityWeightedLbConfig locality_weighted_lb_config = 7

  Enable locality weighted load balancing for ring hash lb explicitly.

The hash function used to hash hosts onto the ketama ring.

Used in: RingHash

• DEFAULT_HASH = 0

  Currently defaults to XX_HASH.

• XX_HASH = 1

  Use `xxHash <https://github.com/Cyan4973/xxHash>`_.

• MURMUR_HASH_2 = 2

  Use `MurmurHash2 <https://sites.google.com/site/murmurhash/>`_, this is compatible with std:hash<string> in GNU libstdc++ 3.4.20 or above. This is typically the case when compiled on Linux and not macOS.