Introduction: Apache Tomcat Upgrading from Tomcat 8 to Tomcat 9 is a critical step for taking advantage of the latest features, improved performance, and enhanced security. This blog provides a structured approach for a successful upgrade.
Why we need to do:
Tomcat 9 introduces support for Servlet 4.0, HTTP/2, and other modern web technologies. Many applications require these features to maintain compatibility and performance. Moreover, Tomcat 8 has reached its end-of-life phase, leaving systems exposed to unpatched vulnerabilities.
Challenges and Issues Faced During Upgradation:
Configuration Incompatibilities: Configuration files such as server.xml, web.xml, and context.xml may require adjustments to align with Tomcat 9 standards.
Application Dependencies: Applications running on Tomcat 8 may rely on deprecated libraries or APIs that are removed in Tomcat 9.
Custom Scripts and Integrations: Custom startup scripts, monitoring tools, or integrations might need modifications for compatibility.
Steps to Upgrade Tomcat from Version 8 to Version 9:
Backup Your Current Setup:
l Backup all configuration files: server.xml, web.xml, context.xml.
l Backup application WAR files and logs.
l Snapshot the current environment to ensure rollback options.
Download and Install Tomcat 9:
l Download the Tomcat 9 binary from the official Apache Tomcat website.
l Extract the archive to a new directory (do not overwrite the existing Tomcat 8 directory).
Migrate Configuration Files:
l Compare the server.xml, web.xml, and context.xml from Tomcat 8 with the default Tomcat 9 configurations.
l Update configurations to align with Tomcat 9 schema. Remove any
deprecated elements.
Migrate Applications:
l Deploy your application WAR files to the webapps directory in the Tomcat 9 installation.
l Test applications for compatibility, focusing on deprecated APIs and libraries.
Update Custom Scripts:
l Modify any startup scripts or custom integrations to reference the new Tomcat 9 directories and binaries.
Test the Upgrade:
l Start Tomcat 9 using the startup.sh or startup.bat script.
l Monitor logs in the logs directory for errors.
l Test all deployed applications to ensure they function as expected.
Rollback Plan:
l If issues are encountered, stop Tomcat 9 and revert to the backup of Tomcat 8.
l Analyze logs and fix configuration or application compatibility issues before retrying the upgrade.
Conclusion: Upgrading from Tomcat 8 to Tomcat 9 is essential for maintaining a secure and modern application environment. While the process may involve challenges like configuration adjustments and dependency updates, following a structured upgrade plan ensures a smooth transition.
