I have routes of this kind. They work fine, but for some reason an error appears in the logs (the last line of the logs). This is due to the fact that the response tries to pass through the filter modifyResponseBody a second time. Why is this happening? And in general, is it considered acceptable as a fallback to redirect a request to a different route?
@Bean
public RouteLocator myRoutes(RouteLocatorBuilder builder) {
RouteLocator build = builder.routes()
.route("normal", p -> p
.path("/read/searchByResource").and().predicate(pr -> !pr.getRequest().getHeaders().containsKey("hello-header"))
.filters(f -> f.modifyResponseBody(GenericResponse.class, SpecificResponse.class,
(serverWebExchange, genericResponse) -> Mono.just(new SpecificResponse(genericResponse)))
.circuitBreaker(c -> c.setName("myCircuitBreaker")
.setFallbackUri("forward:/fallback")
.setStatusCodes(Set.of("500"))))
.uri("http://localhost:8081"))
.route("not normal", p -> p
.path("/fallback")
.filters(f -> f.rewritePath("/fallback", "/read/searchByResource")
)
.uri("http://localhost:8082"))
.build();
return build;
}
2021-04-21 18:37:30.599 TRACE 8108 --- [ctor-http-nio-1] o.s.c.g.f.WeightCalculatorWebFilter : Weights attr: {}
2021-04-21 18:37:30.600 TRACE 8108 --- [ctor-http-nio-1] o.s.c.g.h.p.PathRoutePredicateFactory : Pattern "/read/searchByResource" matches against value "/read/searchByResource"
2021-04-21 18:37:30.600 DEBUG 8108 --- [ctor-http-nio-1] o.s.c.g.h.RoutePredicateHandlerMapping : Route matched: normal
2021-04-21 18:37:30.600 DEBUG 8108 --- [ctor-http-nio-1] o.s.c.g.h.RoutePredicateHandlerMapping : Mapping [Exchange: GET http://localhost:8080/read/searchByResource] to Route{id='normal', uri=http://localhost:8081, order=0, predicate=(Paths: [/read/searchByResource], match trailing slash: true && CiruitBreakerApplication$$Lambda$514/0x0000000800474840), gatewayFilters=[[ModifyResponseBody New content type = [null], In class = GenericResponse, Out class = SpecificResponse], [[SpringCloudCircuitBreakerResilience4JFilterFactory name = 'myCircuitBreaker', fallback = forward:/fallback], order = 0]], metadata={}}
2021-04-21 18:37:30.600 DEBUG 8108 --- [ctor-http-nio-1] o.s.c.g.h.RoutePredicateHandlerMapping : [28e0df6f-2] Mapped to org.springframework.cloud.gateway.handler.FilteringWebHandler@2198c0b4
2021-04-21 18:37:30.600 DEBUG 8108 --- [ctor-http-nio-1] o.s.c.g.handler.FilteringWebHandler : Sorted gatewayFilterFactories: [[GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.RemoveCachedBodyFilter@6f825516}, order = -2147483648], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.AdaptCachedBodyGlobalFilter@33188612}, order = -2147482648], [ModifyResponseBody New content type = [null], In class = GenericResponse, Out class = SpecificResponse], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.NettyWriteResponseFilter@6d229b1c}, order = -1], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.ForwardPathFilter@1b482cbf}, order = 0], [[SpringCloudCircuitBreakerResilience4JFilterFactory name = 'myCircuitBreaker', fallback = forward:/fallback], order = 0], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.RouteToRequestUrlFilter@2da99821}, order = 10000], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.config.GatewayNoLoadBalancerClientAutoConfiguration$NoLoadBalancerClientFilter@7161457}, order = 10150], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.WebsocketRoutingFilter@661fe025}, order = 2147483646], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.NettyRoutingFilter@66a53104}, order = 2147483647], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.ForwardRoutingFilter@62cba181}, order = 2147483647]]
2021-04-21 18:37:30.600 TRACE 8108 --- [ctor-http-nio-1] o.s.c.g.filter.RouteToRequestUrlFilter : RouteToRequestUrlFilter start
2021-04-21 18:37:30.603 TRACE 8108 --- [ctor-http-nio-1] o.s.c.gateway.filter.NettyRoutingFilter : outbound route: 45905ca4, inbound: [28e0df6f-2]
2021-04-21 18:37:30.607 DEBUG 8108 --- [ctor-http-nio-1] i.g.r.c.i.CircuitBreakerStateMachine : CircuitBreaker 'myCircuitBreaker' recorded an exception as failure:
org.springframework.cloud.gateway.filter.factory.SpringCloudCircuitBreakerFilterFactory$CircuitBreakerStatusCodeException: 500 INTERNAL_SERVER_ERROR
at org.springframework.cloud.gateway.filter.factory.SpringCloudCircuitBreakerFilterFactory$1.lambda$filter$0(SpringCloudCircuitBreakerFilterFactory.java:103) ~[spring-cloud-gateway-server-3.0.2.jar:3.0.2]
at reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.onComplete(MonoPeekTerminal.java:289) ~[reactor-core-3.4.5.jar:3.4.5]
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.onComplete(MonoIgnoreThen.java:209) ~[reactor-core-3.4.5.jar:3.4.5]
at reactor.core.publisher.Operators.complete(Operators.java:136) ~[reactor-core-3.4.5.jar:3.4.5]
at reactor.core.publisher.MonoEmpty.subscribe(MonoEmpty.java:45) ~[reactor-core-3.4.5.jar:3.4.5]
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52) ~[reactor-core-3.4.5.jar:3.4.5]
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52) ~[reactor-core-3.4.5.jar:3.4.5]
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.subscribeNext(MonoIgnoreThen.java:236) ~[reactor-core-3.4.5.jar:3.4.5]
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.onComplete(MonoIgnoreThen.java:203) ~[reactor-core-3.4.5.jar:3.4.5]
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2399) ~[reactor-core-3.4.5.jar:3.4.5]
at reactor.core.publisher.MonoFlatMapMany$FlatMapManyMain.onSubscribeInner(MonoFlatMapMany.java:150) ~[reactor-core-3.4.5.jar:3.4.5]
at reactor.core.publisher.MonoFlatMapMany$FlatMapManyMain.onNext(MonoFlatMapMany.java:189) ~[reactor-core-3.4.5.jar:3.4.5]
at reactor.core.publisher.SerializedSubscriber.onNext(SerializedSubscriber.java:99) ~[reactor-core-3.4.5.jar:3.4.5]
at reactor.core.publisher.FluxRetryWhen$RetryWhenMainSubscriber.onNext(FluxRetryWhen.java:173) ~[reactor-core-3.4.5.jar:3.4.5]
at reactor.core.publisher.MonoCreate$DefaultMonoSink.success(MonoCreate.java:160) ~[reactor-core-3.4.5.jar:3.4.5]
at reactor.netty.http.client.HttpClientConnect$HttpIOHandlerObserver.onStateChange(HttpClientConnect.java:388) ~[reactor-netty-http-1.0.6.jar:1.0.6]
at reactor.netty.ReactorNetty$CompositeConnectionObserver.onStateChange(ReactorNetty.java:654) ~[reactor-netty-core-1.0.6.jar:1.0.6]
at reactor.netty.resources.DefaultPooledConnectionProvider$DisposableAcquire.onStateChange(DefaultPooledConnectionProvider.java:196) ~[reactor-netty-core-1.0.6.jar:1.0.6]
at reactor.netty.resources.DefaultPooledConnectionProvider$PooledConnection.onStateChange(DefaultPooledConnectionProvider.java:452) ~[reactor-netty-core-1.0.6.jar:1.0.6]
at reactor.netty.http.client.HttpClientOperations.onInboundNext(HttpClientOperations.java:629) ~[reactor-netty-http-1.0.6.jar:1.0.6]
at reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:94) ~[reactor-netty-core-1.0.6.jar:1.0.6]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:436) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:324) ~[netty-codec-4.1.63.Final.jar:4.1.63.Final]
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:311) ~[netty-codec-4.1.63.Final.jar:4.1.63.Final]
at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:432) ~[netty-codec-4.1.63.Final.jar:4.1.63.Final]
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:276) ~[netty-codec-4.1.63.Final.jar:4.1.63.Final]
at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:251) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:719) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:655) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:581) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493) ~[netty-transport-4.1.63.Final.jar:4.1.63.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989) ~[netty-common-4.1.63.Final.jar:4.1.63.Final]
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.63.Final.jar:4.1.63.Final]
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.63.Final.jar:4.1.63.Final]
at java.base/java.lang.Thread.run(Thread.java:834) ~[na:na]
2021-04-21 18:37:30.608 DEBUG 8108 --- [ctor-http-nio-1] i.g.r.c.i.CircuitBreakerStateMachine : No Consumers: Event ERROR not published
2021-04-21 18:37:30.608 TRACE 8108 --- [ctor-http-nio-1] o.s.c.g.h.p.PathRoutePredicateFactory : Pattern "[/read/searchByResource]" does not match against value "/fallback"
2021-04-21 18:37:30.609 TRACE 8108 --- [ctor-http-nio-1] o.s.c.g.h.p.PathRoutePredicateFactory : Pattern "/fallback" matches against value "/fallback"
2021-04-21 18:37:30.609 DEBUG 8108 --- [ctor-http-nio-1] o.s.c.g.h.RoutePredicateHandlerMapping : Route matched: not normal
2021-04-21 18:37:30.609 DEBUG 8108 --- [ctor-http-nio-1] o.s.c.g.h.RoutePredicateHandlerMapping : Mapping [Exchange: GET /fallback] to Route{id='not normal', uri=http://localhost:8082, order=0, predicate=Paths: [/fallback], match trailing slash: true, gatewayFilters=[[[RewritePath /fallback = '/read/searchByResource'], order = 0]], metadata={}}
2021-04-21 18:37:30.609 DEBUG 8108 --- [ctor-http-nio-1] o.s.c.g.h.RoutePredicateHandlerMapping : [28e0df6f-2] Mapped to org.springframework.cloud.gateway.handler.FilteringWebHandler@2198c0b4
2021-04-21 18:37:30.609 DEBUG 8108 --- [ctor-http-nio-1] o.s.c.g.handler.FilteringWebHandler : Sorted gatewayFilterFactories: [[GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.RemoveCachedBodyFilter@6f825516}, order = -2147483648], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.AdaptCachedBodyGlobalFilter@33188612}, order = -2147482648], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.NettyWriteResponseFilter@6d229b1c}, order = -1], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.ForwardPathFilter@1b482cbf}, order = 0], [[RewritePath /fallback = '/read/searchByResource'], order = 0], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.RouteToRequestUrlFilter@2da99821}, order = 10000], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.config.GatewayNoLoadBalancerClientAutoConfiguration$NoLoadBalancerClientFilter@7161457}, order = 10150], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.WebsocketRoutingFilter@661fe025}, order = 2147483646], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.NettyRoutingFilter@66a53104}, order = 2147483647], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.ForwardRoutingFilter@62cba181}, order = 2147483647]]
2021-04-21 18:37:30.609 TRACE 8108 --- [ctor-http-nio-1] o.s.c.g.filter.RouteToRequestUrlFilter : RouteToRequestUrlFilter start
2021-04-21 18:37:30.610 TRACE 8108 --- [ctor-http-nio-3] o.s.c.gateway.filter.NettyRoutingFilter : outbound route: 31272575, inbound: [28e0df6f-2]
2021-04-21 18:37:30.615 TRACE 8108 --- [ctor-http-nio-3] o.s.c.g.filter.NettyWriteResponseFilter : NettyWriteResponseFilter start inbound: 31272575, outbound: [28e0df6f-2]
2021-04-21 18:37:30.617 TRACE 8108 --- [ctor-http-nio-1] o.s.c.g.filter.NettyWriteResponseFilter : NettyWriteResponseFilter start inbound: 31272575, outbound: [28e0df6f-2]
2021-04-21 18:37:30.618 ERROR 8108 --- [ctor-http-nio-3] o.s.w.s.adapter.HttpWebHandlerAdapter : [28e0df6f-2] Error [java.lang.NullPointerException] for HTTP GET "/read/searchByResource", but ServerHttpResponse already committed (202 ACCEPTED)
