How to Build a Tomcat Runtime on Docker: A Step‑by‑Step Guide

Environment

All commands are executed on a 64‑bit Ubuntu 13.10 server running inside VMware Workstation.

Install Docker

Check AUFS support and kernel version (Docker 0.7 requires Linux 3.8).

sudo apt-get update

sudo apt-get install linux-image-extra-`uname -r`

sudo sh -c "wget -qO- https://get.docker.io/gpg | apt-key add -"

sudo sh -c "echo deb http://get.docker.io/ubuntu docker main > /etc/apt/sources.list.d/docker.list"

sudo apt-get update

sudo apt-get install lxc-docker

Verify installation with sudo docker version (client and server version 0.7.1).

Remove sudo for Docker commands

Create a dedicated docker group and add the current user (e.g., yongboy) to it, then restart the Docker daemon.

sudo groupadd docker

sudo gpasswd -a yongboy docker

sudo service docker restart

After restart, test with docker version. If it still requires sudo, reboot the host ( sudo reboot).

Run a Docker instance (Ubuntu)

Pull the official tutorial image and start a container.

docker pull learn/tutorial

docker run learn/tutorial /bin/echo hello world

Enter the container interactively:

docker run -i -t learn/tutorial /bin/bash

Install SSH server inside the container

apt-get update

apt-get install openssh-server

which sshd

# returns /usr/sbin/sshd

mkdir /var/run/sshd

passwd

# set a password (e.g., 123456) for the root user

exit

Commit the container as a new image

Identify the container ID and commit it. docker ps -l # shows container ID 51774a81beb3

docker commit 51774a81beb3 learn/tutorial

Run the image with SSH and Tomcat ports

docker run -d -p 22 -p 80:8080 learn/tutorial /usr/sbin/sshd -D

Check running containers: docker ps. The SSH port is mapped to a random host port (e.g., 49154).

Connect via SSH:

ssh [email protected] -p 49154

Install Oracle JDK 7 and Tomcat 7.0.47 inside the container

apt-get install python-software-properties

add-apt-repository ppa:webupd8team/java

apt-get update

apt-get install -y wget

apt-get install oracle-java7-installer

java -version

wget http://mirror.bit.edu.cn/apache/tomcat/tomcat-7/v7.0.47/bin/apache-tomcat-7.0.47.tar.gz

tar xvf apache-tomcat-7.0.47.tar.gz

cd apache-tomcat-7.0.47

bin/startup.sh

Tomcat runs on port 8080 inside the container; because the container was started with -p 80:8080, the host’s port 80 forwards to Tomcat. Verify with curl http://192.168.190.131 or a web browser.

Conclusion

Using Docker to assemble a Tomcat runtime is straightforward and demonstrates a basic PAAS scenario. Future articles will cover automated image building with Dockerfiles and deeper explanations of Docker’s architecture and mechanisms.