tomcat

Estimated reading time: 6 minutes

Apache Tomcat is an open source implementation of the Java Servlet and JavaServer Pages technologies

GitHub repo: https://github.com/docker-library/tomcat

Library reference

This content is imported from the official Docker Library docs, and is provided by the original uploader. You can view the Docker Store page for this image at https://store.docker.com/images/tomcat

Supported tags and respective Dockerfile links

Quick reference

What is Tomcat?

Apache Tomcat (or simply Tomcat) is an open source web server and servlet container developed by the Apache Software Foundation (ASF). Tomcat implements the Java Servlet and the JavaServer Pages (JSP) specifications from Oracle, and provides a “pure Java” HTTP web server environment for Java code to run in. In the simplest config Tomcat runs in a single operating system process. The process runs a Java virtual machine (JVM). Every single HTTP request from a browser to Tomcat is processed in the Tomcat process in a separate thread.

wikipedia.org/wiki/Apache_Tomcat

logoLogo © Apache Software Fountation

How to use this image.

Run the default Tomcat server (CMD ["catalina.sh", "run"]):

$ docker run -it --rm tomcat:8.0

You can test it by visiting http://container-ip:8080 in a browser or, if you need access outside the host, on port 8888:

$ docker run -it --rm -p 8888:8080 tomcat:8.0

You can then go to http://localhost:8888 or http://host-ip:8888 in a browser.

The default Tomcat environment in the image for versions 7 and 8 is:

CATALINA_BASE:   /usr/local/tomcat
CATALINA_HOME:   /usr/local/tomcat
CATALINA_TMPDIR: /usr/local/tomcat/temp
JRE_HOME:        /usr
CLASSPATH:       /usr/local/tomcat/bin/bootstrap.jar:/usr/local/tomcat/bin/tomcat-juli.jar

The default Tomcat environment in the image for version 6 is:

CATALINA_BASE:   /usr/local/tomcat
CATALINA_HOME:   /usr/local/tomcat
CATALINA_TMPDIR: /usr/local/tomcat/temp
JRE_HOME:        /usr
CLASSPATH:       /usr/local/tomcat/bin/bootstrap.jar

The configuration files are available in /usr/local/tomcat/conf/. By default, no user is included in the “manager-gui” role required to operate the “/manager/html” web application. If you wish to use this app, you must define such a user in tomcat-users.xml.

Image Variants

The tomcat images come in many flavors, each designed for a specific use case.

tomcat:<version>

This is the defacto image. If you are unsure about what your needs are, you probably want to use this one. It is designed to be used both as a throw away container (mount your source code and start the container to start your app), as well as the base to build other images off of.

tomcat:<version>-slim

This image does not contain the common packages contained in the default tag and only contains the minimal packages needed to run tomcat. Unless you are working in an environment where only the tomcat image will be deployed and you have space constraints, we highly recommend using the default image of this repository.

tomcat:<version>-alpine

This image is based on the popular Alpine Linux project, available in the alpine official image. Alpine Linux is much smaller than most distribution base images (~5MB), and thus leads to much slimmer images in general.

This variant is highly recommended when final image size being as small as possible is desired. The main caveat to note is that it does use musl libc instead of glibc and friends, so certain software might run into issues depending on the depth of their libc requirements. However, most software doesn’t have an issue with this, so this variant is usually a very safe choice. See this Hacker News comment thread for more discussion of the issues that might arise and some pro/con comparisons of using Alpine-based images.

To minimize image size, it’s uncommon for additional related tools (such as git or bash) to be included in Alpine-based images. Using this image as a base, add the things you need in your own Dockerfile (see the alpine image description for examples of how to install packages if you are unfamiliar).

License

View license information for the software contained in this image.

As with all Docker images, these likely also contain other software which may be under other licenses (such as Bash, etc from the base distribution, along with any direct or indirect dependencies of the primary software being contained).

Some additional license information which was able to be auto-detected might be found in the repo-info repository’s tomcat/ directory.

As for any pre-built image usage, it is the image user’s responsibility to ensure that any use of this image complies with any relevant licenses for all software contained within.

library, sample, tomcat