io.grpc.testing.integration.RpcBehaviorLoadBalancerProvider Maven / Gradle / Ivy
/*
* Copyright 2022 The gRPC Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.grpc.testing.integration;
import io.grpc.ConnectivityState;
import io.grpc.LoadBalancer;
import io.grpc.LoadBalancer.Helper;
import io.grpc.LoadBalancer.PickResult;
import io.grpc.LoadBalancer.PickSubchannelArgs;
import io.grpc.LoadBalancer.SubchannelPicker;
import io.grpc.LoadBalancerProvider;
import io.grpc.LoadBalancerRegistry;
import io.grpc.Metadata;
import io.grpc.NameResolver.ConfigOrError;
import io.grpc.Status;
import io.grpc.internal.JsonUtil;
import io.grpc.util.ForwardingLoadBalancer;
import io.grpc.util.ForwardingLoadBalancerHelper;
import java.util.Map;
import javax.annotation.Nonnull;
/**
* Provides a xDS interop test {@link LoadBalancer} designed to work with {@link XdsTestServer}. It
* looks for an "rpc_behavior" field in its configuration and includes the value in the
* "rpc-behavior" metadata entry that is sent to the server. This will cause the test server to
* behave in a predefined way. Endpoint picking logic is delegated to the
* io.grpc.util.RoundRobinLoadBalancer.
*
* Initial use case is to prove that a custom load balancer can be configured by the control
* plane via xDS. An interop test will configure this LB and then verify it has been correctly
* configured by observing a specific RPC behavior by the server(s).
*
*
For more details on what behaviors can be specified, please see:
* https://github.com/grpc/grpc/blob/master/doc/xds-test-descriptions.md#server
*/
public class RpcBehaviorLoadBalancerProvider extends LoadBalancerProvider {
@Override
public ConfigOrError parseLoadBalancingPolicyConfig(Map rawLoadBalancingPolicyConfig) {
String rpcBehavior = JsonUtil.getString(rawLoadBalancingPolicyConfig, "rpcBehavior");
if (rpcBehavior == null) {
return ConfigOrError.fromError(
Status.UNAVAILABLE.withDescription("no 'rpcBehavior' defined"));
}
return ConfigOrError.fromConfig(new RpcBehaviorConfig(rpcBehavior));
}
@Override
public LoadBalancer newLoadBalancer(Helper helper) {
RpcBehaviorHelper rpcBehaviorHelper = new RpcBehaviorHelper(helper);
return new RpcBehaviorLoadBalancer(rpcBehaviorHelper,
LoadBalancerRegistry.getDefaultRegistry().getProvider("round_robin")
.newLoadBalancer(rpcBehaviorHelper));
}
@Override
public boolean isAvailable() {
return true;
}
@Override
public int getPriority() {
return 5;
}
@Override
public String getPolicyName() {
return "test.RpcBehaviorLoadBalancer";
}
static class RpcBehaviorConfig {
final String rpcBehavior;
RpcBehaviorConfig(String rpcBehavior) {
this.rpcBehavior = rpcBehavior;
}
}
/**
* Delegates all calls to another LB and wraps the given helper in {@link RpcBehaviorHelper} that
* assures that the rpc-behavior metadata header gets added to all calls.
*/
static class RpcBehaviorLoadBalancer extends ForwardingLoadBalancer {
private final RpcBehaviorHelper helper;
private final LoadBalancer delegateLb;
RpcBehaviorLoadBalancer(RpcBehaviorHelper helper, LoadBalancer delegateLb) {
this.helper = helper;
this.delegateLb = delegateLb;
}
@Override
protected LoadBalancer delegate() {
return delegateLb;
}
@Override
public void handleResolvedAddresses(ResolvedAddresses resolvedAddresses) {
helper.setRpcBehavior(
((RpcBehaviorConfig) resolvedAddresses.getLoadBalancingPolicyConfig()).rpcBehavior);
delegateLb.handleResolvedAddresses(resolvedAddresses);
}
}
/**
* Wraps the picker that is provided when the balancing change updates with the {@link
* RpcBehaviorPicker} that injects the rpc-behavior metadata entry.
*/
static class RpcBehaviorHelper extends ForwardingLoadBalancerHelper {
private final Helper delegateHelper;
private String rpcBehavior;
RpcBehaviorHelper(Helper delegateHelper) {
this.delegateHelper = delegateHelper;
}
void setRpcBehavior(String rpcBehavior) {
this.rpcBehavior = rpcBehavior;
}
@Override
protected Helper delegate() {
return delegateHelper;
}
@Override
public void updateBalancingState(@Nonnull ConnectivityState newState,
@Nonnull SubchannelPicker newPicker) {
delegateHelper.updateBalancingState(newState, new RpcBehaviorPicker(newPicker, rpcBehavior));
}
}
/**
* Includes the rpc-behavior metadata entry on each subchannel pick.
*/
static class RpcBehaviorPicker extends SubchannelPicker {
private static final String RPC_BEHAVIOR_HEADER_KEY = "rpc-behavior";
private final SubchannelPicker delegatePicker;
private final String rpcBehavior;
RpcBehaviorPicker(SubchannelPicker delegatePicker, String rpcBehavior) {
this.delegatePicker = delegatePicker;
this.rpcBehavior = rpcBehavior;
}
@Override
public PickResult pickSubchannel(PickSubchannelArgs args) {
args.getHeaders()
.put(Metadata.Key.of(RPC_BEHAVIOR_HEADER_KEY, Metadata.ASCII_STRING_MARSHALLER),
rpcBehavior);
return delegatePicker.pickSubchannel(args);
}
}
}