I have a Spring Webflux application that is deployed on Digital Ocean Kubernetes with Proxy Protocol enabled because the app needs to get access to the client IP.

Here are Kubernetes resource descriptions:

---
apiVersion: v1
kind: Service
metadata:
  name: myapp-loadbalancer
  annotations:
    service.beta.kubernetes.io/do-loadbalancer-enable-proxy-protocol: "true"
spec:
  type: LoadBalancer
  selector:
    app: myapp
  ports:
    - name: http
      protocol: TCP
      port: 80
      targetPort: 8080

---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: ipregistry-api
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
        - name: myapp
          image: myapp/myapp:1553679009241
          ports:
            - containerPort: 8080
          readinessProbe:
            httpGet:
              path: /actuator/health
              port: 8080
            initialDelaySeconds: 10
            periodSeconds: 5
            successThreshold: 1
      imagePullSecrets:
        - name: regcred

The deployment works great. Unfortunately, when I perform a GET request to any app endpoint I get an HTTP 400 response.

By looking at the logs I noticed that Spring Webflux and the underlying Netty library that is used does not parse the request properly when proxy protocol is enabled.

Please note that if the proxy protocol is disabled by setting service.beta.kubernetes.io/do-loadbalancer-enable-proxy-protocol to false then everything works but I cannot get the real client IP.

Here is the error I get in the logs when debugging is enabled:

2019-03-27 09:33:45.916 DEBUG 1 --- [or-http-epoll-1] r.n.http.server.HttpServerOperations     : [id: 0x3c2ee440, L:/10.244.2.230:8080 - R:/10.131.95.63:27204] New http connection, requesting read 2019-03-27 09:33:45.916 DEBUG 1 --- [or-http-epoll-1] reactor.netty.channel.BootstrapHandlers  : [id: 0x3c2ee440, L:/10.244.2.230:8080 - R:/10.131.95.63:27204] Initialized pipeline DefaultChannelPipeline{(BootstrapHandlers$BootstrapInitializerHandler#0
= reactor.netty.channel.BootstrapHandlers$BootstrapInitializerHandler), (reactor.left.httpCodec = io.netty.handler.codec.http.HttpServerCodec), (reactor.left.httpTrafficHandler = reactor.netty.http.server.HttpTrafficHandler), (reactor.right.reactiveBridge = reactor.netty.channel.ChannelOperationsHandler)} 2019-03-27 09:33:45.917 DEBUG 1 --- [or-http-epoll-1] r.n.http.server.HttpServerOperations     : [id: 0x3c2ee440, L:/10.244.2.230:8080 - R:/10.131.95.63:27204] Decoding failed: DefaultFullHttpRequest(decodeResult: failure(java.lang.IllegalArgumentException: invalid version format:
83.252.136.179 10.16.5.223 3379 80), version: HTTP/1.0, content: UnpooledByteBufAllocator$InstrumentedUnpooledUnsafeHeapByteBuf(ridx: 0, widx: 0, cap: 0)) GET /bad-request HTTP/1.0 : 

java.lang.IllegalArgumentException: invalid version format:
83.252.136.179 10.16.5.223 3379 80  at io.netty.handler.codec.http.HttpVersion.<init>(HttpVersion.java:121) ~[netty-codec-http-4.1.33.Final.jar:4.1.33.Final]   at io.netty.handler.codec.http.HttpVersion.valueOf(HttpVersion.java:76) ~[netty-codec-http-4.1.33.Final.jar:4.1.33.Final]   at io.netty.handler.codec.http.HttpRequestDecoder.createMessage(HttpRequestDecoder.java:87) ~[netty-codec-http-4.1.33.Final.jar:4.1.33.Final]   at io.netty.handler.codec.http.HttpObjectDecoder.decode(HttpObjectDecoder.java:219) ~[netty-codec-http-4.1.33.Final.jar:4.1.33.Final]   at io.netty.handler.codec.http.HttpServerCodec$HttpServerRequestDecoder.decode(HttpServerCodec.java:101) ~[netty-codec-http-4.1.33.Final.jar:4.1.33.Final]  at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:502) ~[netty-codec-4.1.33.Final.jar:4.1.33.Final]   at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:441) ~[netty-codec-4.1.33.Final.jar:4.1.33.Final]   at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:278) ~[netty-codec-4.1.33.Final.jar:4.1.33.Final]  at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:253) ~[netty-transport-4.1.33.Final.jar:4.1.33.Final]    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) ~[netty-transport-4.1.33.Final.jar:4.1.33.Final]    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) ~[netty-transport-4.1.33.Final.jar:4.1.33.Final]    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) ~[netty-transport-4.1.33.Final.jar:4.1.33.Final]  at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1408) ~[netty-transport-4.1.33.Final.jar:4.1.33.Final]   at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) ~[netty-transport-4.1.33.Final.jar:4.1.33.Final]    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) ~[netty-transport-4.1.33.Final.jar:4.1.33.Final]    at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:930) ~[netty-transport-4.1.33.Final.jar:4.1.33.Final]    at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:799) ~[netty-transport-native-epoll-4.1.33.Final-linux-x86_64.jar:4.1.33.Final]     at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:427) ~[netty-transport-native-epoll-4.1.33.Final-linux-x86_64.jar:4.1.33.Final]   at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:328) ~[netty-transport-native-epoll-4.1.33.Final-linux-x86_64.jar:4.1.33.Final]    at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:905) ~[netty-common-4.1.33.Final.jar:4.1.33.Final]   at java.base/java.lang.Thread.run(Thread.java:834) ~[na:na]

I tried to use the property server.use-forward-headers=true in my application properties but it has no effect.

Is there a way to support Proxy Protocol with Spring Webflux? How to proceed? An example would help a lot.