1# xDS Features in gRPC 2 3This document lists the [xDS](https://github.com/envoyproxy/data-plane-api/tree/master/envoy/api/v2) 4features supported in various gRPC language implementations and versions. 5 6Note that a gRPC client will simply ignore the configuration of a feature it 7does not support. The gRPC client does not generate a log 8to indicate that some configuration was ignored. It is impractical to generate 9a log and keep it up-to-date because xDS has a large number of APIs that gRPC 10does not support and the APIs keep evolving too. We recommend reading the 11[first gRFC](https://github.com/grpc/proposal/blob/master/A27-xds-global-load-balancing.md) 12on xDS support in gRPC to understand the design philosophy. 13 14The EDS policy will *not* support 15[overprovisioning](https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/upstream/load_balancing/overprovisioning), 16which is different from Envoy. Envoy takes the overprovisioning into 17account in both [locality-weighted load balancing](https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/upstream/load_balancing/locality_weight) 18and [priority failover](https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/upstream/load_balancing/priority), 19but gRPC assumes that the xDS server will update it to redirect traffic 20when this kind of graceful failover is needed. gRPC will send the 21[`envoy.lb.does_not_support_overprovisioning` client 22feature](https://github.com/envoyproxy/envoy/pull/10136) to the xDS 23server to tell the xDS server that it will not perform graceful failover; 24xDS server implementations may use this to decide whether to perform 25graceful failover themselves. 26 27The EDS policy will not support per-endpoint stats; it will report only 28per-locality stats. 29 30An [`lb_endpoint`](https://github.com/envoyproxy/envoy/blob/12a4bc430eaf440ceb0d11286cfbd4c16b79cdd1/api/envoy/api/v2/endpoint/endpoint_components.proto#L72) 31is ignored if the `health_status` is not HEALTHY or UNKNOWN. 32The optional `load_balancing_weight` is always ignored. 33 34Initially, only `google_default` channel creds will be supported 35to authenticate with the xDS server. 36 37Features | gRFCs | [C++, Python,<br> Ruby, PHP, C#](https://github.com/grpc/grpc/releases) | [Java](https://github.com/grpc/grpc-java/releases) | [Go](https://github.com/grpc/grpc-go/releases) 38---------|--------|--------------|------|------ 39**xDS Infrastructure in gRPC client channel:**<br>LDS->RDS->CDS->EDS flow,<br>ADS stream, | [A27](https://github.com/grpc/proposal/blob/master/A27-xds-global-load-balancing.md) | v1.30.0 | v1.30.0 | v1.30.0 | 40**Load Balancing:**<br>Virtual host matching,<br>Only default path ("" or "/") matching,<br>Priority-based weighted round-robin locality picking,<br>Round-robin endpoint picking within locality,<br>Cluster route action,<br>Client-side Load reporting via [LRS](https://github.com/envoyproxy/data-plane-api/blob/master/envoy/service/load_stats/v2/lrs.proto)| [A27](https://github.com/grpc/proposal/blob/master/A27-xds-global-load-balancing.md) | v1.30.0 | v1.30.0 | v1.30.0 | 41