Support running the gateway with other reactive containers besides netty

[muzuro]

I am trying to use tomcat instead netty. To achive this i have excluded netty from dependencies and included tomcat, so my build.gradle dependecies:

dependencies {
    compile (group: 'org.springframework.cloud', name: 'spring-cloud-starter-gateway', version: '2.0.0.M4') {
        exclude group: 'org.springframework.boot', module: 'spring-boot-starter-netty'
    }
    compile group: 'org.springframework.boot', name: 'spring-boot-starter-tomcat', version: '2.0.0.M7'
    compile group: 'org.springframework.boot', name: 'spring-boot-starter-webflux'
}

Hower it is not enough, i get ClassCastException:

java.lang.ClassCastException: org.springframework.core.io.buffer.DefaultDataBufferFactory cannot be cast to org.springframework.core.io.buffer.NettyDataBufferFactory
	at org.springframework.cloud.gateway.filter.NettyWriteResponseFilter.lambda$filter$0(NettyWriteResponseFilter.java:61) ~[spring-cloud-gateway-core-2.0.0.M4.jar:2.0.0.M4]
	at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:44) ~[reactor-core-3.1.1.RELEASE.jar:3.1.1.RELEASE]
	at reactor.core.publisher.Mono.subscribe(Mono.java:2913) ~[reactor-core-3.1.1.RELEASE.jar:3.1.1.RELEASE]
	at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:167) ~[reactor-core-3.1.1.RELEASE.jar:3.1.1.RELEASE]

Is it possible to use tomcat with gateway instead netty? Thanks!

[spencergibb]

Not currently.

[spencergibb]

I already have code for this that just needs to be formalized. The difficulty will be running all the tests with other containers.

[grku2opia]

@spencergibb can u provide code ?

[spencergibb]

WebClientHttpRoutingFilter and WebClientWriteResponseFilter

[ghost]

@spencergibb How is the progress now? Thank you

[spencergibb]

None so far

[ghoddg]

Hi, I am also facing the same issue and the error is as below

java.lang.ClassCastException: org.springframework.core.io.buffer.DefaultDataBufferFactory cannot be cast to org.springframework.core.io.buffer.NettyDataBufferFactory at org.springframework.cloud.gateway.filter.NettyWriteResponseFilter.lambda$filter$0(NettyWriteResponseFilter.java:61) ~[spring-cloud-gateway-core-2.0.0.BUILD-SNAPSHOT.jar:2.0.0.BUILD-SNAPSHOT]

[spencergibb]

@ghoddg this is likely not going to happen in 2.0.0. For now you have to use netty.

[ghoddg]

Hi @spencergibb .. I am starting my api gateway service with tomcat. The service is started properly but when i hit api, it is giving me the above error

Also, my requirement is that I want to deploy it on weblogic as war and then also it should work is it possible?

[spencergibb]

No

[ghoddg]

@spencergibb Thanks for update.

[ghoddg]

@spencergibb , from above communication, i got understanding that, API Gateway Service with Spring Cloud Gateway will not work with Tomcat as well as Weblogic for now and it will work only with netty. is my understanding correct?

[dharezlak]

Hello, I have a similar problem without Tomcat nor Jetty in classpath. The error I am getting is the following:

java.lang.ClassCastException: org.springframework.core.io.buffer.DefaultDataBufferFactory cannot be cast to org.springframework.core.io.buffer.NettyDataBufferFactory
	at org.springframework.cloud.gateway.filter.NettyWriteResponseFilter.lambda$filter$0(NettyWriteResponseFilter.java:61) ~[spring-cloud-gateway-core-2.0.0.M6.jar:2.0.0.M6]
	at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:44) ~[reactor-core-3.1.3.RELEASE.jar:3.1.3.RELEASE]
	at reactor.core.publisher.Mono.subscribe(Mono.java:3006) ~[reactor-core-3.1.3.RELEASE.jar:3.1.3.RELEASE]
	at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:167) ~[reactor-core-3.1.3.RELEASE.jar:3.1.3.RELEASE]
	at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.ignoreDone(MonoIgnoreThen.java:185) ~[reactor-core-3.1.3.RELEASE.jar:3.1.3.RELEASE]
	at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreInner.onComplete(MonoIgnoreThen.java:234) ~[reactor-core-3.1.3.RELEASE.jar:3.1.3.RELEASE]
	at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:245) ~[reactor-core-3.1.3.RELEASE.jar:3.1.3.RELEASE]
	at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:130) ~[reactor-core-3.1.3.RELEASE.jar:3.1.3.RELEASE]
	at reactor.core.publisher.FluxRetryPredicate$RetryPredicateSubscriber.onComplete(FluxRetryPredicate.java:107) ~[reactor-core-3.1.3.RELEASE.jar:3.1.3.RELEASE]
	at reactor.core.publisher.MonoCreate$DefaultMonoSink.success(MonoCreate.java:140) ~[reactor-core-3.1.3.RELEASE.jar:3.1.3.RELEASE]
	at reactor.ipc.netty.channel.PooledClientContextHandler.fireContextActive(PooledClientContextHandler.java:84) ~[reactor-netty-0.7.3.RELEASE.jar:0.7.3.RELEASE]
	at reactor.ipc.netty.http.client.HttpClientOperations.onInboundNext(HttpClientOperations.java:551) ~[reactor-netty-0.7.3.RELEASE.jar:0.7.3.RELEASE]
	at reactor.ipc.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:134) ~[reactor-netty-0.7.3.RELEASE.jar:0.7.3.RELEASE]
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:438) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:310) ~[netty-codec-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:297) ~[netty-codec-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:413) ~[netty-codec-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:265) ~[netty-codec-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:253) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1412) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:943) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:141) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:645) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:580) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:497) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:459) ~[netty-transport-4.1.20.Final.jar:4.1.20.Final]
	at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:886) ~[netty-common-4.1.20.Final.jar:4.1.20.Final]
	at java.lang.Thread.run(Thread.java:748) ~[na:1.8.0_151]

Is there another dependency that could cause this problem?

My Spring boot 2.0.0.RC1 dependencies are the following:

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-webflux</artifactId>
</dependency>
<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-gateway</artifactId>
</dependency>
<dependency>
	<groupId>org.springframework.session</groupId>
	<artifactId>spring-session-core</artifactId>
</dependency>
<dependency>
	<groupId>com.hazelcast</groupId>
	<artifactId>hazelcast</artifactId>
</dependency>

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-test</artifactId>
	<scope>test</scope>
</dependency>
<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-contract-wiremock</artifactId>
</dependency>
<dependency>
	<groupId>io.projectreactor</groupId>
	<artifactId>reactor-test</artifactId>
	<scope>test</scope>
</dependency>

[dharezlak]

I just noticed that this error occurs only in the testing mode. When run normally the gateway forwarding works fine.

[dharezlak]

Another thing I noticed is that when I use WebClient in tests instead of WebTestClient all is fine. Should using WebTestClient in spring-gateway based applications be prohibited?

[spencergibb]

It's not. It is used to test the gateway

[dharezlak]

@spencergibb It is indeed. The source of my problem was using the @AutoConfigureWebTestClient annotation. Without it my tests are working fine. When I use it I get the ClassCastException mentioned earlier. Do you think this calls for a separate issue?

[drdamour]

are u open to pr's for tomcat support? for 2.0 or 2.1

[spencergibb]

@drdamour I already have code https://github.com/spring-cloud/spring-cloud-gateway/issues/145#issuecomment-358772643. The trouble is testing everything.

[drdamour]

yeah i assumed you meant unit test and thus PR.

what type of testing are you referring to then?

[spencergibb]

Basically all the integration tests. Anything that spins up a container then makes real network calls thru the gateway.

[drdamour]

k...how are you hoping to structure the tests...duality for every netty test have a tomcat test. or just abstract away the backing implementation in all the tests?

or is there some prior art you are looking to follow?

[spencergibb]

My guess is rerunning all the tests with some system properties. Copied tests is prohibitive. Most have a base class already.

[drdamour]

how will that work with your maven circle build? just 2+ surefire/failsafe executions?

[spencergibb]

jenkins is our canonical build

[drdamour]

ok doesn't change anything right? still just calls maven goals (i'm assuming) and i'm guessing you want to test all reactive containers supported on each build?

[spencergibb]

There's another problem of including tomcat, jetty etc...

[drdamour]

def could make the netty container the default profile and have other profiles that bring in the others & exclude netty..but the build couldn't be done as one command AFAIK (don't think you can switch profiles/classpaths with extra executions of surefire or failsafe). Never tried though..maybe. could do the tests as other modules..but that'd either mean sharing a test jar from core or copy paste tests over.

good problem...

[ghost]

Maybe you can try to cancel the dependency ---providedRuntime('org.springframework.boot:spring-boot-starter-tomcat')

[SachinSharmaa]

I am also facing the same issue and i do not want to migrate my services from tomcat to netty. Any idea, when can we expect the fix?