> On 2025 Apr 23, at 20:02, Zoran Avtarovski <zo...@sparecreative.com> wrote:
>
> We have a cluster of tomcat servers on AWS EC2 which operate behind an AWS
> load balancer with sticky sessions.
>
> We have our session storage on a DB using a JDBC store which for the most
> part is working well, but we occasionally see duplicate session ids which
> create issues where a new session with a duplicate session id hijacks an
> existing session.
>
> As you can imagine we would like to prevent this from occurring and have been
> looking into the issue. It looks like using the cluster tag might be the
> solution but I wanted to tap into the collective wisdom of the group on the
> best way forward. We can't just add the
>
> |<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/> |
>
> tag as it uses ip multicast which doesn't work in EC2 as there is no physical
> broadcast layer. The alternative appears to be to use the
> StaticMemebrshipService and I wanted to confirm if my config ideas are
> correct? I have the following setup:
>
> <Membership
> className="org.apache.catalina.tribes.membership.StaticMembershipService">
> <Member className="org.apache.catalina.tribes.membership.StaticMember"
> host="10.0.1.11" port="4004"
> uniqueId="{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15}"/>
> <Member className="org.apache.catalina.tribes.membership.StaticMember"
> host="10.0.1.12" port="4004"
> uniqueId="{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,1}"/>
> </Membership>
>
> Does this look right to others and do I need a separate Member tag for each
> member of the cluster?
>
> I'd appreciate any assistance on this and other suggestions you guys may have.
Have you specified a unique jvmRoute attribute in the <Engine> element of each
Tomcat server?
https://tomcat.apache.org/tomcat-9.0-doc/config/engine.html#Common_Attributes
- Chuck
