Release Notes - Tomcat 9
Posted by on 14 June 2018 04:19 PM
Overview - Tomcat 9
This Release Note covers all point releases for the Tomcat 9 that are offered by eApps. Upgrade instructions are included.
Tomcat 9 is only available for Virtual Servers running CentOS 6 or CentOS 7. If you are on a CentOS 5 (Webmin) or CentOS 4 (VPS) plan and need Tomcat 9, you will need to migrate to a CentOS 6 (ISPmanager) plan. Contact eApps Sales for more information.
Tomcat 9 is designed to run on Java SE 8 and above. There is no support for Java SE 7 in Tomcat 9
eApps recommends, as a best practice, to maintain a staging server where you can test software upgrades before moving them into production. This approach will allow you to minimize the risk of data loss and downtime of your production service when performing software upgrades. If necessary, you can rebuild your staging Virtual Server on demand so that you have a fresh installation to test on. If you need more information about setting up a Virtual Server for staging or testing, please contact eApps Sales.
IMPORTANT: Tomcat 9 has an extensive list of new features and changes. See the Official Tomcat 9 Release Notes for a list of changes that may cause issues when upgrading: https://tomcat.apache.org/tomcat-9.0-doc/RELEASE-NOTES.txt. Please read this document carefully to understand all the changes in the Tomcat 9 release. Upgrading to this version may significantly impact the operation of your database and applications. All Tomcat 9 documentation is located here: https://tomcat.apache.org/tomcat-9.0-doc/
If you are migrating Tomcat applications from an existing version of Tomcat to Tomcat 9, please see the Apache Tomcat Migration Guide: https://tomcat.apache.org/migration-9.html
Highlighted Features and Fixes in Tomcat 9.0.8
Please see the ChangeLog, and scroll down to find the relevant information for this specific release: https://tomcat.apache.org/tomcat-9.0-doc/changelog.html
How to Upgrade
It is your responsibility to ensure that your application will work on the newer version of Tomcat. There may be incompatibilities that will affect how your application works. Please make sure that you have read the official Release Notes and Changelog, and have done any necessary testing before upgrading a production application.
You should also make a backup of your application, your configuration, and any tunings or changes you have made. If you do not have current backups and something goes wrong during the upgrade process, you could have data loss.
To upgrade Tomcat, you will need to work from the command line using SSH, and you will need to be able to work as the root user. You will need to use yum to upgrade the application.
Tomcat 6 or Tomcat 7 or Tomcat 8 to Tomcat 9
There is no direct upgrade path between major Tomcat versions, such as between Tomcat 6 or Tomcat 7 to Tomcat 9. If you are on Tomcat 6 or 7, you will need to back up your applications (usually in the /opt/tomcatX/webapps directory, where X is your version of Tomcat), your data, and any configuration files you have changed. Then uninstall the existing version of Tomcat, install Tomcat 9, and then redeploy your applications. If you try to install Tomcat 9 without first uninstalling the previous Tomcat version, the installation may fail.
When you redeploy your applications, you will also need to update the Tomcat configuration files, such as server.xml. Please note - do not copy the entire file, just the specific HOST blocks that you added. If you try to use the server.xml from a previous version of Tomcat, then the new version of Tomcat will crash.
To remove the existing version of Tomcat, use the
This will remove the main directories from the /opt/tomcatX directory, but the tomcatX directory will still remain.
If you are using Java SE 6 or Java SE 7, you will need to remove it and install Java SE 8. You will need to install Java SE 8 BEFORE installing Tomcat 9. If you try to install Tomcat 9 before installing Java SE 8, Tomcat 9 will not start.
Remove Java SE 6 with the
Remove Java SE 7 with the
Once you have removed the existing version of Tomcat (and if necessary have removed Java SE 6 and Java SE 7 and intalled Java SE 8), install Tomcat 9 using the
Once the installation completes, you will need to redeploy your applications and copy over your configuration files, and test.
Tomcat 9.x to Tomcat 9.y (newer version)
Before upgrading, make a backup of your applications (usually in /opt/tomcat8/webapps), any configuration files you have changed, and your data. This way you can redeploy your applications if necessary after the upgrade.
Upgrade Tomcat using the
Once the update completes, test your existing applications.