Issues with vertx HTTP Proxy module

Evaristo Camarero

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Feb 12, 2024, 3:51:14 AM2/12/24

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Hi there,

I am using HTTP vertx module, and I have encountered some issues. I wante to double check if the use of the API I am doing is wrong.

My use case requires, to proxy the request to multiple origins based on processing some headers and querying a DB in order to determine the origin. Looks to me that makes sense to delay ProxyRequest creation until I can know the origin (in case it fails the DB access)

I am using the low level API as demonstrated in https://github.com/eclipse-vertx/vertx-http-proxy/blob/main/src/main/java/examples/HttpProxyExamples.java

If I delay the creation ProxyRequest, basically the proxy functionally does NOT work.

I include a reproducer. Port 7070 used for origin, port 8080 handler shows the issue, port 9090 works because ProxyRequest is NOT delayed.

Thanks in advance,

Evaristo

curl -X GET -v http://localhost:8080

Example.java

package com.cheva.proxy;

import io.vertx.core.Handler;
import io.vertx.core.Vertx;
import io.vertx.core.http.HttpClient;
import io.vertx.core.http.HttpServerRequest;
import io.vertx.httpproxy.ProxyRequest;

public class Example{

public static void main(String[] args) throws Exception {

final Vertx vertx = Vertx.vertx();
vertx
.createHttpServer()
.requestHandler(
req -> {
req.response()
.putHeader("content-type", "text/html")
.end("<html><body><h1>I'm the target resource!</h1></body></html>");
})
.listen(7070);

final HttpClient proxyClient = vertx.createHttpClient();

vertx.createHttpServer().requestHandler(hanldeRequestNoOk(vertx, proxyClient)).listen(8080);
vertx.createHttpServer().requestHandler(hanldeRequestOk(vertx, proxyClient)).listen(9090);
}

private static Handler<HttpServerRequest> hanldeRequestOk(
final Vertx vertx, final HttpClient proxyClient) {

return request -> {
ProxyRequest proxyRequest = ProxyRequest.reverseProxy(request);
vertx
.<Integer>executeBlocking(() -> getPort(), false)
.onSuccess(
port -> {
System.out.println("XXX1 " + port);
// ProxyRequest proxyRequest = ProxyRequest.reverseProxy(request);
System.out.println("XXX2 " + proxyRequest);
proxyClient
.request(proxyRequest.getMethod(), port, "localhost", proxyRequest.getURI())
.compose(
proxyHttpRequest -> {
System.out.println("XXX3");
return proxyRequest.send(proxyHttpRequest);
})
.onSuccess(
proxyResponse -> {
System.out.println("XXX4");
// Send the proxy response
proxyResponse.send().onFailure(err -> err.printStackTrace());
})
.onFailure(
err -> {
err.printStackTrace();
// Release the request
proxyRequest.release();
// Send error
request.response().setStatusCode(500).send();
});
})
.onFailure(err -> err.printStackTrace());
};
}

private static Handler<HttpServerRequest> hanldeRequestNoOk(
final Vertx vertx, final HttpClient proxyClient) {

return request -> {
vertx
.<Integer>executeBlocking(() -> getPort(), false)
.onSuccess(
port -> {
System.out.println("XXX1 " + port);
ProxyRequest proxyRequest = ProxyRequest.reverseProxy(request);
System.out.println("XXX2 " + proxyRequest);
proxyClient
.request(proxyRequest.getMethod(), port, "localhost", proxyRequest.getURI())
.compose(
proxyHttpRequest -> {
System.out.println("XXX3");
return proxyRequest.send(proxyHttpRequest);
})
.onSuccess(
proxyResponse -> {
System.out.println("XXX4");
// Send the proxy response
proxyResponse.send().onFailure(err -> err.printStackTrace());
})
.onFailure(
err -> {
err.printStackTrace();
// Release the request
proxyRequest.release();
// Send error
request.response().setStatusCode(500).send();
});
})
.onFailure(err -> err.printStackTrace());
};
}

private static Integer getPort() throws InterruptedException {
Thread.sleep(10L);
return 7070;
}
}

GERARD Nicolas

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Feb 14, 2024, 11:00:53 AM2/14/24

to vert.x

I don't dig into the code but a proxy is just a http client making another request.

Here a minimal example:

https://github.com/vert-x3/vertx-examples/blob/4.x/core-examples/src/main/java/io/vertx/example/core/http/proxy/Proxy.java

Evaristo Camarero

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Feb 15, 2024, 2:49:32 AM2/15/24

to vert.x

Thanks Gerard.

I have no problems understanding the functionality (my use case it is bit more elaborate that simple one). Basically the code will decide the origin getting a request header and making a query to external DB in order to pick the right origin. In order to do that, the request handler in the proxy server is composing a set of Futures (one of them access an external DB with blocking API (using vertx.executeBlocking...) in order to determine the origin that I will proxy the request)

If I delay ProxyRequest creation until DB has answered back I get this exception that hopefully can ring a bell:

java.lang.IllegalStateException: Request has already been read
            at io.vertx.core.http.impl.Http2ServerRequest.checkEnded(Http2ServerRequest.java:209) ~[vertx-core-4.5.3.jar:4.5.3]
            at io.vertx.core.http.impl.Http2ServerRequest.pause(Http2ServerRequest.java:261) ~[vertx-core-4.5.3.jar:4.5.3]
            at io.vertx.httpproxy.ProxyRequest.reverseProxy(ProxyRequest.java:41) ~[vertx-http-proxy-4.5.3.jar:4.5.3]

Regards,

Evaristo

GERARD Nicolas

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Feb 15, 2024, 3:29:48 AM2/15/24

to vert.x

Hy Evaristo.

As far as I remember, I tried the proxy module

when it was still in early development

and I got also some weird behavior.

They still have a preview status

https://vertx.io/docs/4.1.8/vertx-http-proxy/java/

I went with an adaptation of the previous code

adding just an extra request to handle the redirection.

May be, there was a better way to debug the proxy module and add it to our

project but my knowledge of code binding of external repos is pretty limited.

Cheers

Nico

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