apache-tomcat-10-image/README.openjdk21.md

Tomcat 10 container image

Description

Apache Tomcat (Tomcat for short) is a free and open-source implementation of the Jakarta Servlet, Jakarta Expression Language, and WebSocket technologies. It provides a pure Java HTTP web server environment that can run Java code. It is a Java web application server and not a complete JEE application server.

Usage

By default, the image launches Tomcat with the same configuration as the one that comes with SUSE Linux Enterprise Server. The difference is that logging is sent to stdout, meaning that the podman logs tomcat command displays Tomcat logs.

For security reasons, the image runs as the tomcat user and is installed on a micro base container without a package manager.

To deploy an application, copy the .war file into $CATALINA_BASE/webapps (either during a container build or by bind-mounting the directory), and launch the container using the following command:

$ podman run -d --rm -p 8080:8080 registry.opensuse.org/opensuse/apache-tomcat:10.1-openjdk21

The deployed webapp is then accessible via http://localhost:8080/$webapp_name.

How to use the image with rootless Podman

The container image can be used in rootless mode with Podman. Keep in mind that Podman remaps the tomcat user in the container to a different user on the host. This user does not have write access to the mounted directory. To avoid permission issues change permissions of the shared directory to 0777 as follows:

$ chmod 0777 /path/to/my/app
$ podman run --rm -d -v /path/to/my/app:/usr/share/tomcat/webapps:z \
      -p 8080:8080 registry.opensuse.org/opensuse/apache-tomcat:10.1-openjdk21

Configuration

The main Tomcat configuration files (for example /etc/tomcat/logging.properties) are stored in /etc/tomcat/.

Tomcat's runtime options can be configured using the environment variables JAVA_OPTS and CATALINA_OPTS. JAVA_OPTS specifies general options used for the JVM, whereas CATALINA_OPTS specifies Tomcat's flags. You can pass the options to the container runtime using the -e flag:

$ podman run -it --rm \
      -e JAVA_OPTS="-Xmx1024m" -p 8080:8080 \
      registry.opensuse.org/opensuse/apache-tomcat:10.1-openjdk21

The image ships with CATALINA_HOME set to /usr/share/tomcat and CATALINA_BASE set to /usr/share/tomcat.

Upgrading from Tomcat 9

Tomcat 9 implements Java EE 8, and Tomcat 10 implements Jakarta EE 9. Before upgrading from version 9, consult the upstream migration guide.

Licensing

SPDX-License-Identifier: MIT

This documentation and the build recipe are licensed as MIT. The container itself contains various software components under various open source licenses listed in the associated Software Bill of Materials (SBOM).

This image is based on openSUSE Tumbleweed.