Our help documentation (https://help.sodius.cloud/help/topic/com.sodius.oslc.app.jira-cloud.doc/resources/install/index.html?cp=0_0) guides topology and versions of Tomcat and Postgres.
While each deployment is slightly different, we can provide general guidance on the application hardware that supports them.
For the Tomcat server, we recommend: 4 CPU/4 GB RAM/20GB Storage
For the Postgres server, we recommend: 2 CPU/4 GB RAM/20GB Storage
Please review the firewall policies for the Tomcat server as it needs to be able to access, and be accessed from, both Jira Cloud and your OSLC Application (example IBM ELM or Siemens Polarion).