I would use the max-conncections
attribute as defined in the documentation. Either for http and/or https connections. It is defined as
"The maximum number of concurrent connections. Only values greater
than 0 are allowed. For unlimited connections simply undefine this
attribute value."
I don't see the benefit of defining an extra filter. But maybe the others can shed some light on this... So similar to the other solutions it would look like this:
<subsystem xmlns="urn:jboss:domain:undertow:10.0">
[...]
<server name="default-server">
<http-listener name="default" socket-binding="http" max-connections="3000" redirect-socket="https" enable-http2="true"/>
<https-listener name="https" socket-binding="https" max-connections="3000" security-realm="ApplicationRealm" enable-http2="true" />
[...]
</server>
[...]
</subsystem>
Update: I just realized that this is the standalone.xml solution to what Francesco is proposing...