Spring boot address and port number issue - spring

Question

I was looking for possible root cause of the problem reported here (SO thread) - Cannot start a Tomcat v9.0 server in eclipse.
While fiddling for above (unrelated to the thread above mentioned), accidentally, instead of
server.port=8080
I put below in my application.properties file
server.address=8080
When I tried to start server I kept getting this error before I realized the typo.
***************************
APPLICATION FAILED TO START
***************************
Description:
Web server failed to start. Port 8080 was already in use
When I replaced "address" with "port", all worked fine.
Question: Is it expected behavior or a known defect or a possible new defect? If its a new defect, where can I report it on Spring Community?
UPDATE
Per the comments on github issue tracker https://github.com/spring-projects/spring-boot/issues/21101, it is fixed now and the fix will be released in next release 2.2.7

Answer 1

Spring Boot was unable to bind the server to the invalid address 8080.
And the default message is
Web server failed to start. Port 8080 was already in use
You can try to set
server.addresss=9090
and you will get the same message.
The error message is just misleading.
The message is generated in PortInUseFailureAnalyzer
And the PortInUseException is thrown here:
public void start() throws WebServerException {
synchronized (this.monitor) {
if (this.started) {
return;
}
try {
addPreviouslyRemovedConnectors();
Connector connector = this.tomcat.getConnector();
if (connector != null && this.autoStart) {
performDeferredLoadOnStartup();
}
checkThatConnectorsHaveStarted();
this.started = true;
logger.info("Tomcat started on port(s): " + getPortsDescription(true) + " with context path '"
+ getContextPath() + "'");
}
catch (ConnectorStartFailedException ex) {
stopSilently();
throw ex;
}
catch (Exception ex) {
if (findBindException(ex) != null) {
throw new PortInUseException(this.tomcat.getConnector().getPort());
}
throw new WebServerException("Unable to start embedded Tomcat server", ex);
}
finally {
Context context = findContext();
ContextBindings.unbindClassLoader(context, context.getNamingToken(), getClass().getClassLoader());
}
}
}