Strange behavior of server.port property in Tomcat - spring

Question

Actually, it is not a problem, but a strange thing I would like to understand. I use SpringBoot2 with embedded Tomcat. And I've added self-signed SSL certificate. This is pretty usual config:
server.ssl.key-store-type=PKCS12
server.ssl.key-store=classpath:keystore.p12
server.ssl.key-store-password=123456
server.ssl.key-alias=tomcat
server.port=8443
And I made a connector, to force http -> https redirect, like in many examples:
private Connector getHttpConnector() {
Connector connector = new Connector("org.apache.coyote.http11.Http11NioProtocol");
connector.setScheme("http");
connector.setPort(8080);
connector.setSecure(false);
connector.setRedirectPort(8443);
return connector;
}
If I would not specify server.port property in my config, I will see the following error:
Description:
The Tomcat connector configured to listen on port 8080 failed to
start. The port may already be in use or the connector may be
misconfigured.
Action:
Verify the connector's configuration, identify and stop any process
that's listening on port 8080, or configure this application to listen
on another port.
But if I will, I will see following:
o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s):
8443 (https) 8080 (http) with context path ''
Why server.port starts to point at https port??? Even sources of springframework.boot.autoconfigure.web.ServerProperties says that it is
/**
* Server HTTP port.
*/
Is it ok, or I've got something strange in my server? Or this is how Conectors works? :) Thank you

Answer 1

By default, the embedded server start on port 8080 if you don't give any value for server.port in the properties file
And you are also specifying connectors port as 8080 (connector.setPort(8080);)
Hence you are getting port conflicts.