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docker-tomcat

A docker base image to build a container for Tomcat based on Alpine

This image is intended to build a base for providing a tomcat instance to host java applications. It depends on the baseimage ragedunicorn/openjdk:1.3.0-jdk-stable from RagedUnicorn/docker-java. Make sure to locally build this image or put it in a repository.

Version

  • Tomcat 9

For an exact version see Dockerfile

Using the image

Start container

The container can be easily started with docker-compose command.

By default tomcat will be reachable on 127.0.0.1:8080

docker-compose up -d

Stop container

To stop all services from the docker-compose file

docker-compose down

Creating a stack

To create a stack the specific docker-compose.stack.yml file can be used. It requires that you already built the image that is consumed by the stack or that it is available in a reachable docker repository.

docker-compose build --no-cache

Note: You will get a warning that external secrets are not supported by docker-compose if you try to use this file with docker-compose.

Join a swarm

docker swarm init

Create secrets

echo "app_user" | docker secret create com.ragedunicorn.tomcat.app_user -
echo "app_user_password" | docker secret create com.ragedunicorn.tomcat.app_user_password -

Deploy stack

docker stack deploy --compose-file=docker-compose.stack.yml [stackname]

For a production deployment a stack should be deployed. The secret will then be taken into account and Tomcat will be setup accordingly. You can also set a password in conf\tomcat-users.xml but this is not recommended for production.

Dockery

In the dockery folder are some scripts that help out avoiding retyping long docker commands but are mostly intended for playing around with the container. For production docker-compose or docker stack should be used.

Build image

The build script builds an image with a defined name

sh dockery/dbuild.sh

Run container

Runs the built container. If the container was already run once it will docker start the already present container instead of using docker run

sh dockery/drun.sh

Attach container

Attaching to the container after it is running

sh dockery/dattach.sh

Stop container

Stopping the running container

sh dockery/dstop.sh

Configuration

Default user

The Tomcat configuration is located in config and can be easily changed.

The default user is: admin:admin

To change this you can edit config/tomcat-users.xml.

Note: This does not apply to a stack deployment. Make sure to set both password and user with docker secrets.

Build Args

The image allows for certain arguments being overridden by build args.

TOMCAT_USER, TOMCAT_GROUP

They all have a default value and don't have to be overridden. For details see the Dockerfile.

Healthcheck

The production and the stack image supports a simple healthcheck showing whether the container is healthy or not. This can be configured inside docker-compose.yml or docker-compose.stack.yml

Test

To do basic tests of the structure of the container use the docker-compose.test.yml file.

docker-compose -f docker-compose.test.yml up

For more info see container-test.

Tests can also be run by category such as command, fileExistence and metadata tests by starting single services in docker-compose.test.yml

# basic file existence tests
docker-compose -f docker-compose.test.yml up container-test
# command tests
docker-compose -f docker-compose.test.yml up container-test-command
# metadata tests
docker-compose -f docker-compose.test.yml up container-test-metadata

The same tests are also available for the development image.

# basic file existence tests
docker-compose -f docker-compose.test.yml up container-dev-test
# command tests
docker-compose -f docker-compose.test.yml up container-dev-test-command
# metadata tests
docker-compose -f docker-compose.test.yml up container-dev-test-metadata

Development

To debug the container and get more insight into the container use the docker-compose.dev.yml configuration.

docker-compose -f docker-compose.dev.yml up -d

By default the launchscript /docker-entrypoint.sh will not be used to start the Tomcat process. Instead the container will be setup to keep stdin_open open and allocating a pseudo tty. This allows for connecting to a shell and work on the container. A shell can be opened inside the container with docker attach [container-id]. Tomcat itself can be started with ./docker-entrypoint.sh.

The Tomcat server also exposes jmx access on port 60334 when built with the developer configuration. To connect to the server use a tool like jconsole and its url 127.0.0.1:60334

Links

Alpine packages database

License

Copyright (C) 2021 Michael Wiesendanger

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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Repository for Docker Tomcat image based on Alpine

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