For reproducing https://github.com/elastic/apm-server/issues/3452

ClientWithResponseHandler.java

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 * to you under the Apache License, Version 2.0 (the
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package org.apache.hc.client5.http.examples;

import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;

import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSession;

import org.apache.hc.client5.http.classic.methods.HttpGet;
import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
import org.apache.hc.client5.http.impl.classic.HttpClients;
import org.apache.hc.client5.http.impl.io.PoolingHttpClientConnectionManagerBuilder;
import org.apache.hc.client5.http.io.HttpClientConnectionManager;
import org.apache.hc.client5.http.protocol.HttpClientContext;
import org.apache.hc.client5.http.ssl.SSLConnectionSocketFactory;
import org.apache.hc.client5.http.ssl.SSLConnectionSocketFactoryBuilder;
import org.apache.hc.core5.http.HttpHost;
import org.apache.hc.core5.http.io.entity.EntityUtils;
import org.apache.hc.core5.http.ssl.TLS;
import org.apache.hc.core5.ssl.SSLContexts;
import org.apache.hc.core5.ssl.TrustStrategy;

/**
 * Make HTTPS request without verifying certificates
 */
public class ClientCustomSSL {
    public final static void main(final String[] args) throws Exception {
        final SSLContext sslcontext = SSLContexts.custom()
                .loadTrustMaterial(new TrustStrategy() {
                    @Override
                    public boolean isTrusted(final X509Certificate[] chain, final String authType) throws CertificateException {
                        return true;
                    }
                })
                .build();
        final SSLConnectionSocketFactory sslSocketFactory = SSLConnectionSocketFactoryBuilder.create()
                .setSslContext(sslcontext)
                .setTlsVersions(TLS.V_1_2, TLS.V_1_3)
                .build();
        final HttpClientConnectionManager cm = PoolingHttpClientConnectionManagerBuilder.create()
                .setSSLSocketFactory(sslSocketFactory)
                .build();
        try (CloseableHttpClient httpclient = HttpClients.custom()
                .setConnectionManager(cm)
                .build()) {

            final HttpGet httpget = new HttpGet(args[0]);

            System.out.println("Executing request " + httpget.getMethod() + " " + httpget.getUri());

            final HttpClientContext clientContext = HttpClientContext.create();
            try (CloseableHttpResponse response = httpclient.execute(httpget, clientContext)) {
                System.out.println("----------------------------------------");
                System.out.println(response.getCode() + " " + response.getReasonPhrase());
                System.out.println(EntityUtils.toString(response.getEntity()));

                final SSLSession sslSession = clientContext.getSSLSession();
                if (sslSession != null) {
                    System.out.println("SSL protocol " + sslSession.getProtocol());
                    System.out.println("SSL cipher suite " + sslSession.getCipherSuite());
                }
            }
        }
    }
}

To use, grab a 5.0 distribution from http://hc.apache.org/downloads.cgi for:

httpclient5-5.0.jar
httpcore5-5.0.jar
slf4j-api-1.7.25.jar

Run an apm-server with ssl enabled:

apm-server-7.6.1 -e -E apm-server.ssl.enabled=true -E apm-server.ssl.certificate=server.crt -E apm-server.ssl.key=server.key -E output.elasticsearch.enabled=false -E output.console.enabled=true

To reproduce the issue, use a jdk <=13.0.2:

java -cp httpcore5-5.0.jar:httpclient5-5.0.jar:slf4j-api-1.7.25.jar ./ClientWithResponseHandler.java https://localhost:8200/

To demonstrate a workaround, add -Djdk.tls.client.protocols=TLSv1.2 like:

java -cp httpcore5-5.0.jar:httpclient5-5.0.jar:slf4j-api-1.7.25.jar -Djdk.tls.client.protocols=TLSv1.2 ./ClientWithResponseHandler.java https://localhost:8200/

For another workaround, start apm-server without TLSv1.3 enabled:

apm-server-7.6.1 -e -E apm-server.ssl.enabled=true -E apm-server.ssl.certificate=server.crt -E apm-server.ssl.key=server.key -E output.elasticsearch.enabled=false -E output.console.enabled=true -E apm-server.ssl.supported_protocols='[TLSv1.1,TLSv1.2]'

To generate a self signed cert, be sure to set the CN appropriately (localhost in this reproduction):

openssl genrsa -des3 -passout pass:x -out server.pass.key 2048
openssl rsa -passin pass:x -in server.pass.key -out server.key
rm server.pass.key
openssl req -new -key server.key -out server.csr
openssl x509 -req -sha256 -days 365 -in server.csr -signkey server.key -out server.crt