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<div class="title">xDS Features in gRPC </div> </div>
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<div class="textblock"><p>This document lists the <a href="https://github.com/envoyproxy/data-plane-api/tree/master/envoy/api/v2">xDS</a> features supported in various gRPC language implementations and versions.</p>
<p>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. We recommend reading the <a href="https://github.com/grpc/proposal/blob/master/A27-xds-global-load-balancing.md">first gRFC</a> on xDS support in gRPC to understand the design philosophy.</p>
<p>The EDS policy will <em>not</em> support <a href="https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/upstream/load_balancing/overprovisioning">overprovisioning</a>, which is different from Envoy. Envoy takes the overprovisioning into account in both <a href="https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/upstream/load_balancing/locality_weight">locality-weighted load balancing</a> and <a href="https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/upstream/load_balancing/priority">priority failover</a>, 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 <a href="https://github.com/envoyproxy/envoy/pull/10136"><code>envoy.lb.does_not_support_overprovisioning</code> client feature</a> 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.</p>
<p>The EDS policy will not support per-endpoint stats; it will report only per-locality stats.</p>
<p>An <a href="https://github.com/envoyproxy/envoy/blob/12a4bc430eaf440ceb0d11286cfbd4c16b79cdd1/api/envoy/api/v2/endpoint/endpoint_components.proto#L72"><code>lb_endpoint</code></a> is ignored if the <code>health_status</code> is not HEALTHY or UNKNOWN. The optional <code>load_balancing_weight</code> is always ignored.</p>
<p>Initially, only <code>google_default</code> channel creds will be supported to authenticate with the xDS server.</p>
<table class="markdownTable">
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<th class="markdownTableHeadNone">Features </th><th class="markdownTableHeadNone">gRFCs </th><th class="markdownTableHeadNone"><a href="https://github.com/grpc/grpc/releases">C++, Python, Ruby, PHP, C#</a> </th><th class="markdownTableHeadNone"><a href="https://github.com/grpc/grpc-java/releases">Java</a> </th><th class="markdownTableHeadNone"><a href="https://github.com/grpc/grpc-go/releases">Go</a> </th></tr>
<tr class="markdownTableRowOdd">
<td class="markdownTableBodyNone"><b>xDS Infrastructure in gRPC client channel:</b><br />
LDS-&gt;RDS-&gt;CDS-&gt;EDS flow,<br />
ADS stream, </td><td class="markdownTableBodyNone"><a href="https://github.com/grpc/proposal/blob/master/A27-xds-global-load-balancing.md">A27</a> </td><td class="markdownTableBodyNone">v1.30.0 </td><td class="markdownTableBodyNone">v1.30.0 </td><td class="markdownTableBodyNone">v1.30.0 </td></tr>
<tr class="markdownTableRowEven">
<td class="markdownTableBodyNone"><b>Load Balancing:</b><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 <a href="https://github.com/envoyproxy/data-plane-api/blob/master/envoy/service/load_stats/v2/lrs.proto">LRS</a> </td><td class="markdownTableBodyNone"><a href="https://github.com/grpc/proposal/blob/master/A27-xds-global-load-balancing.md">A27</a> </td><td class="markdownTableBodyNone">v1.30.0 </td><td class="markdownTableBodyNone">v1.30.0 </td><td class="markdownTableBodyNone">v1.30.0 </td></tr>
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