This document lists the xDS features supported in various gRPC language implementations and versions.

Note that a gRPC client will simply ignore the configuration of a feature it does not support. The gRPC client does not generate a log to indicate that some configuration was ignored. It is impractical to generate a log and keep it up-to-date because xDS has a large number of APIs that gRPC does not support and the APIs keep evolving too. In the case where an xDS field corresponding to a feature is supported but the value configured for that field is not supported, a gRPC client will NACK such a configuration. We recommend reading the first gRFC on xDS support in gRPC to understand the design philosophy.

Not all cluster load balancing policies are supported. A gRPC client will NACK the configuration that contains unsupported cluster load balancing policy. This will cause all cluster configurations to be rejected by the client because the xDS protocol currently requires rejecting all resources in a given response, rather than being able to reject only an individual resource from the response. Due to this limitation, you must ensure that all clients support the required cluster load balancing policy before configuring that policy for a service. For example, if you change the ROUND_ROBIN policy to RING_HASH, you must ensure that all the clients are upgraded to a version that supports RING_HASH.

The EDS policy will not support overprovisioning, which is different from Envoy. Envoy takes the overprovisioning into account in both locality-weighted load balancing and priority failover, but gRPC assumes that the xDS server will update it to redirect traffic when this kind of graceful failover is needed. gRPC will send the envoy.lb.does_not_support_overprovisioning client feature to the xDS server to tell the xDS server that it will not perform graceful failover; xDS server implementations may use this to decide whether to perform graceful failover themselves.

The EDS policy will not support per-endpoint stats; it will report only per-locality stats.

An lb_endpoint is ignored if the health_status is not HEALTHY or UNKNOWN. The optional load_balancing_weight is always ignored.

Initially, only google_default channel creds will be supported to authenticate with the xDS server.

The gRPC language implementations not listed in the table below do not support xDS features.