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Chapter 6. Known issues

Description
You cannot directly register KubernetesServiceImporter() with the Reactive Extensions (Rx) for Eclipse Vert.x.
Cause
Service importers do not have a generated RxJava 2 implementation.
Workaround
You must create an instance of KubernetesServiceImporter and encapsulate it with {@link io.vertx.reactivex.servicediscovery.spi.ServiceImporter} as shown in the following example: 
{@link examples.RxServiceDiscoveryExamples#register(io.vertx.reactivex.servicediscovery.ServiceDiscovery)}

The following example shows how to register KubernetesServiceImporter() in Eclipse Vert.x Reactive Extensions (Rx). 

ServiceDiscovery discovery = ServiceDiscovery.create(vertx);
discovery.getDelegate().registerServiceImporter(new KubernetesServiceImporter(), new JsonObject());

The Red Hat AMQ Streams Operator and Kafka images are not available for IBM Z and IBM Power Systems. Since the images are not available, the vertx-kafka-client module is not certified to work with AMQ Streams on IBM Z and IBM Power Systems.

Description

Attempting to open a TLS-secured connection using OpenSSL between an application container built on a RHEL 8-based OpenJDK builder image and a database container built on a RHEL 7-based MySQL 5.7 container image results in a connection failure due to a javax.net.ssl.SSLHandshakeException at runtime: For more detail, view the issue in JIRA. 

...
Caused by: javax.net.ssl.SSLHandshakeException: No appropriate protocol (protocol is disabled or cipher suites are inappropriate)
...

Cause

The issue occurs due to a difference in the latest supported TLS protocol version between RHEL 7 and RHEL 8. The TLS implementation on RHEL 7 supports TLS protocol versions 1.0 (deprecated), 1.1, and 1.2. The TLS implementation on RHEL 8 also supports TLS protocol version 1.3, which is also the default TLS version used in RHEL 8-based builder images. This discrepancy may cause a TLS protocol version mismatch between application components while negotiating a TLS handshake, which in turn causes the connection between the application and database containers to fail.

Workaround

To prevent the issue described above, manually specify a TLS protocol version that is supported on both operating system versions in your database connection string. For example: 

jdbc:mysql://testdb-mysql:3306/testdb?enabledTLSProtocols=TLSv1.2

Making an HTTP request on an endpoint of an Eclipse Vert.x application using either the curl tool or a Java HTTP client, produces the following error in the logs after each request: 

io.vertx.core.net.impl.ConnectionBase
SEVERE: java.io.IOException: Connection reset by peer

This behavior is caused by the interaction of the Netty application framework and the HAProxy load-balancer used by OpenShift. The error occurs due to existing HTTP connections being re-used by HAProxy without closing. Even though the error message is logged, no error condition occurs. HTTP requests are handled correctly and the application responds as expected.

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