What is Tomcat?

Apache Tomcat, often referred to as Tomcat, is an open-source web server and servlet container developed by the Apache Software Foundation (ASF). Tomcat implements several Java EE specifications including Java Servlet, JavaServer Pages (JSP), Java EL, and WebSocket, and provides a "pure Java" HTTP web server environment for Java code to run in.

TLDR

docker run --name tomcat bitnami/tomcat:latest

Docker Compose

tomcat:
  image: bitnami/tomcat:latest

Get this image

The recommended way to get the Bitnami Tomcat Docker Image is to pull the prebuilt image from the Docker Hub Registry.

docker pull bitnami/tomcat:latest

To use a specific version, you can pull a versioned tag. You can view the list of available versions in the Docker Hub Registry.

docker pull bitnami/tomcat:[TAG]

If you wish, you can also build the image yourself.

docker build -t bitnami/tomcat:latest https://github.com/bitnami/bitnami-docker-tomcat.git

Persisting your Tomcat configurations and deployments

If you remove the container all your Tomcat configurations and deployments will be lost. To avoid this you should mount a volume that will persist even after the container is removed.

Note! If you have already started using your Tomcat deployment, follow the steps on backing up and restoring to pull the data from your running container down to your host.

The image exposes a volume at /bitnami/tomcat for the Tomcat configurations and application deployments. For persistence you can mount a directory at this location from your host. If the mounted directory is empty, it will be initialized on the first run.

docker run -v /path/to/tomcat-persistence:/bitnami/tomcat bitnami/tomcat:latest

or using Docker Compose:

tomcat:
  image: bitnami/tomcat:latest
  volumes:
    - /path/to/tomcat-persistence:/bitnami/tomcat

Deploying web applications on Tomcat

The /bitnami/tomcat/data directory is configured as the Tomcat webapps deployment directory. At this location, you either copy a so-called exploded web application, i.e. non-compressed, or a compressed web application resource (.WAR) file and it will automatically be deployed by Tomcat.

Additionally a helper symlink /app is present that points to the webapps deployment directory which enables us to deploy applications on a running Tomcat instance by simply doing:

docker cp /path/to/app.war tomcat:/app

Note! You can also deploy web applications on a running Tomcat instance using the Tomcat management interface.

Further Reading:

• Tomcat Web Application Deployment

Accessing your Tomcat server from the host

To access your web server from your host machine you can ask Docker to map a random port on your host to port 8080 exposed in the container.

docker run --name tomcat -P bitnami/tomcat:latest

Run docker port to determine the random ports Docker assigned.

$ docker port tomcat
8080/tcp -> 0.0.0.0:32768

You can also manually specify the ports you want forwarded from your host to the container.

docker run -p 8080:8080 bitnami/tomcat:latest

Access your web server in the browser by navigating to http://localhost:8080.

Configuration

Creating a custom user

By default, a management user named user is created and is not assigned a password. Passing the TOMCAT_PASSWORD environment variable when running the image for the first time will set the password of this user to the value of TOMCAT_PASSWORD.

Additionally you can specify a user name for the management user using the TOMCAT_USER environment variable. When not specified, the TOMCAT_PASSWORD configuration is applied on the default user (user).

docker run --name tomcat \
  -e TOMCAT_USER=my_user \
  -e TOMCAT_PASSWORD=my_password \
  bitnami/tomcat:latest

or using Docker Compose:

tomcat:
  image: bitnami/tomcat:latest
  environment:
    - TOMCAT_USER=my_user
    - TOMCAT_PASSWORD=my_password

Configuration files

This image looks for Tomcat configuration files in /bitnami/tomcat/conf. You may recall from the persisting your tomcat configurations and deployments section, /bitnami/tomcat is the path to the persistence volume.

Create a directory named conf/ at this location with your own configuration, or the default configuration will be copied on the first run which can be customized later.

Step 1: Run the Tomcat image

Run the Tomcat image, mounting a directory from your host.

docker run --name tomcat -v /path/to/tomcat-persistence:/bitnami/tomcat bitnami/tomcat:latest

or using Docker Compose:

tomcat:
  image: bitnami/tomcat:latest
  volumes:
    - /path/to/tomcat-persistence:/bitnami/tomcat

Step 2: Edit the configuration

Edit the configuration on your host using your favorite editor.

eg.

vim /path/to/tomcat-persistence/conf/server.xml

Step 3: Restart Tomcat

After changing the configuration, restart your Tomcat container for the changes to take effect.

docker restart tomcat

or using Docker Compose:

docker-compose restart tomcat

Further Reading:

• Tomcat 7 Configuration Reference

Logging

The Bitnami Tomcat Docker image sends the container logs to the stdout. To view the logs:

docker logs tomcat

or using Docker Compose:

docker-compose logs tomcat

You can configure the containers logging driver using the --log-driver option if you wish to consume the container logs differently. In the default configuration docker uses the json-file driver.

Maintenance

Backing up your container

To backup your configuration and logs, follow these simple steps:

Step 1: Stop the currently running container

docker stop tomcat

or using Docker Compose:

docker-compose stop tomcat

Step 2: Run the backup command

We need to mount two volumes in a container we will use to create the backup: a directory on your host to store the backup in, and the volumes from the container we just stopped so we can access the data.

docker run --rm -v /path/to/tomcat-backups:/backups --volumes-from tomcat busybox \
  cp -a /bitnami/tomcat /backups/latest

or using Docker Compose:

docker run --rm -v /path/to/tomcat-backups:/backups --volumes-from `docker-compose ps -q tomcat` busybox \
  cp -a /bitnami/tomcat /backups/latest

Restoring a backup

Restoring a backup is as simple as mounting the backup as volumes in the container.

docker run -v /path/to/tomcat-backups/latest:/bitnami/tomcat bitnami/tomcat:latest

or using Docker Compose:

tomcat:
  image: bitnami/tomcat:latest
  volumes:
    - /path/to/tomcat-backups/latest:/bitnami/tomcat

Upgrade this image

Bitnami provides up-to-date versions of Tomcat, including security patches, soon after they are made upstream. We recommend that you follow these steps to upgrade your container.

Step 1: Get the updated image

docker pull bitnami/tomcat:latest

or if you're using Docker Compose, update the value of the image property to bitnami/tomcat:latest.

Step 2: Stop and backup the currently running container

Before continuing, you should backup your container's configuration and logs.

Follow the steps on creating a backup.

Step 3: Remove the currently running container

docker rm -v tomcat

or using Docker Compose:

docker-compose rm -v tomcat

Step 4: Run the new image

Re-create your container from the new image, restoring your backup if necessary.

docker run --name tomcat bitnami/tomcat:latest

or using Docker Compose:

docker-compose start tomcat

Testing

This image is tested for expected runtime behavior, using the Bats testing framework. You can run the tests on your machine using the bats command.

bats test.sh

Notable Changes

8.0.35-r0

• All volumes have been merged at /bitnami/tomcat. Now you only need to mount a single volume at /bitnami/tomcat for persistence.
• The logs are always sent to the stdout and are no longer collected in the volume.

Contributing

We'd love for you to contribute to this container. You can request new features by creating an issue, or submit a pull request with your contribution.

Issues

If you encountered a problem running this container, you can file an issue. For us to provide better support, be sure to include the following information in your issue:

• Host OS and version
• Docker version (docker version)
• Output of docker info
• Version of this container (echo $BITNAMI_APP_VERSION inside the container)
• The command you used to run the container, and any relevant output you saw (masking any sensitive information)

License

Copyright 2015 Bitnami

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.