Class LocalityLbPolicy (0.11.0)

The load balancing algorithm used within the scope of the locality. The possible values are:

::

• ROUND_ROBIN: This is a simple policy in which each healthy backend is selected in round robin order. This is the default.
• LEAST_REQUEST: An O(1) algorithm which selects two random healthy hosts and picks the host which has fewer active requests.
• RING_HASH: The ring/modulo hash load balancer implements consistent hashing to backends. The algorithm has the property that the addition/removal of a host from a set of N hosts only affects 1/N of the requests.
• RANDOM: The load balancer selects a random healthy host.
• ORIGINAL_DESTINATION: Backend host is selected based on the client connection metadata, i.e., connections are opened to the same address as the destination address of the incoming connection before the connection was redirected to the load balancer.
• MAGLEV: used as a drop in replacement for the ring hash load balancer. Maglev is not as stable as ring hash but has faster table lookup build times and host selection times. For more information about Maglev, see Maglev: A Fast and Reliable Software Network Load Balancer.

• WEIGHTED_ROUND_ROBIN: Per-endpoint Weighted Round Robin Load Balancing using weights computed from Backend reported Custom Metrics. If set, the Backend Service responses are expected to contain non-standard HTTP response header field Endpoint-Load-Metrics. The reported metrics to use for computing the weights are specified via thecustomMetrics field.

  This field is applicable to either:

  • A regional backend service with the service protocol set to HTTP, HTTPS, HTTP2 or H2C, and load_balancing_scheme set to INTERNAL_MANAGED.
  • A global backend service with the load_balancing_scheme set to INTERNAL_SELF_MANAGED, INTERNAL_MANAGED, or EXTERNAL_MANAGED.

If sessionAffinity is not configured—that is, if session affinity remains at the default value of NONE—then the default value for localityLbPolicy is ROUND_ROBIN. If session affinity is set to a value other than NONE, then the default value for localityLbPolicy isMAGLEV.

Only ROUND_ROBIN and RING_HASH are supported when the backend service is referenced by a URL map that is bound to target gRPC proxy that has validateForProxyless field set to true.

localityLbPolicy cannot be specified with haPolicy.

    A Fast and Reliable Software Network Load
    Balancer.
ORIGINAL_DESTINATION (166297216):
    Backend host is selected based on the client
    connection metadata, i.e., connections are
    opened to the same address as the destination
    address of the incoming connection before the
    connection was redirected to the load balancer.
RANDOM (262527171):
    The load balancer selects a random healthy
    host.
RING_HASH (432795069):
    The ring/modulo hash load balancer implements
    consistent hashing to backends. The algorithm
    has the property that the addition/removal of a
    host from a set of N hosts only affects 1/N of
    the requests.
ROUND_ROBIN (153895801):
    This is a simple policy in which each healthy
    backend is selected in round robin order. This
    is the default.
WEIGHTED_GCP_RENDEZVOUS (82501640):
    Per-instance weighted Load Balancing via
    health check reported weights. In internal
    passthrough network load balancing, it is
    weighted rendezvous hashing.
    This option is only supported in internal
    passthrough network load balancing.
WEIGHTED_MAGLEV (254930962):
    Per-instance weighted Load Balancing via health check
    reported weights. If set, the Backend Service must configure
    a non legacy HTTP-based Health Check, and health check
    replies are expected to contain non-standard HTTP response
    header field X-Load-Balancing-Endpoint-Weight to specify the
    per-instance weights. If set, Load Balancing is weighted
    based on the per-instance weights reported in the last
    processed health check replies, as long as every instance
    either reported a valid weight or had UNAVAILABLE_WEIGHT.
    Otherwise, Load Balancing remains equal-weight. This option
    is only supported in Network Load Balancing.
WEIGHTED_ROUND_ROBIN (5584977):
    Per-endpoint weighted round-robin Load
    Balancing using weights computed from Backend
    reported Custom Metrics. If set, the Backend
    Service responses are expected to contain
    non-standard HTTP response header field
    Endpoint-Load-Metrics. The reported metrics
    to use for computing the weights are specified
    via the customMetrics fields.