Demo Build Tomcat image

In this tutorial, you’ll learn how to create a Docker image for Apache Tomcat on a CentOS 7 base. We’ll introduce a build-time argument (ARG) for Tomcat versioning, and demonstrate how to override it at build time.

Prerequisites
Clone the Repository
Reviewing the Dockerfile
Dockerfile Instruction Reference
Building and Running the Default Image
Building with a Custom Tomcat Version
Links and References

Prerequisites

Docker Engine installed (≥ 19.03)
Basic familiarity with Docker commands
Internet access to download Tomcat and sample WAR

Ensure you have enough disk space (~500 MB) and proper network connectivity to Apache archives.

Clone the Repository

Get the sample project containing our Dockerfile:

cd /tmp
git clone https://github.com/yogeshraheja/dockertomcat.git
cd dockertomcat
ls -ltr
# README.md  Dockerfile

Reviewing the Dockerfile

Below is the complete Dockerfile. It installs OpenJDK 8, downloads Tomcat into /opt/tomcat, sets permissions, and deploys a sample WAR file.

FROM centos:7

# Define a build-time variable for Tomcat version
ARG tomcat_version=8.5.6

# Install prerequisites
RUN yum install -y epel-release java-1.8.0-openjdk.x86_64 wget

# Create tomcat group and home directory
RUN groupadd tomcat && mkdir -p /opt/tomcat

# Create non-interactive tomcat user
RUN useradd -s /bin/nologin -g tomcat -d /opt/tomcat tomcat

# Download and extract Tomcat
WORKDIR /
RUN wget https://archive.apache.org/dist/tomcat/tomcat-8/v${tomcat_version}/bin/apache-tomcat-${tomcat_version}.tar.gz \
 && tar -zxvf apache-tomcat-${tomcat_version}.tar.gz -C /opt/tomcat --strip-components=1

# Set ownership and permissions
RUN cd /opt/tomcat \
 && chgrp -R tomcat conf bin lib logs temp webapps work \
 && chmod g+rx conf \
 && chmod g+r conf/* \
 && chown -R tomcat tomcat logs temp webapps work \
 && chmod g+r bin/*

# Deploy sample application
WORKDIR /opt/tomcat/webapps
RUN wget https://tomcat.apache.org/tomcat-7.0-doc/appdev/sample/sample.war

# Expose port and define startup command
EXPOSE 8080
CMD ["/opt/tomcat/bin/catalina.sh","run"]

Dockerfile Instruction Reference

Instruction	Description	Example
`FROM`	Base image	`centos:7`
`ARG`	Build-time variable; default Tomcat version	`ARG tomcat_version=8.5.6`
`RUN`	Execute shell commands (install, create, download)	`yum install -y java-1.8.0-openjdk wget`
`WORKDIR`	Set working directory	`/opt/tomcat/webapps`
`EXPOSE`	Document container port	`8080`
`CMD`	Default command when container starts	`["/opt/tomcat/bin/catalina.sh","run"]`

Building and Running the Default Image

Build with the default Tomcat version (8.5.6):

docker build -t yogeshraheja/tomcatone:v1 .

Expected output:

Successfully built <IMAGE_ID>
Successfully tagged yogeshraheja/tomcatone:v1

Run the container, mapping host port 84 to container port 8080:

docker run -d --name tomcat_default -p 84:8080 yogeshraheja/tomcatone:v1

Now visit http://<host>:84 in your browser. You should see the Tomcat welcome page for version 8.5.6.

Building with a Custom Tomcat Version

You can override tomcat_version at build time to use any release from the Apache Tomcat Archive:

docker build \
  --build-arg tomcat_version=8.5.8 \
  -t yogeshraheja/tomcatone:v2 .

Sample output:

Successfully built <NEW_IMAGE_ID>
Successfully tagged yogeshraheja/tomcatone:v2

Verify both images:

docker image ls yogeshraheja/tomcatone
# REPOSITORY             TAG    IMAGE ID       SIZE
# yogeshraheja/tomcatone  v2     <NEW_IMAGE_ID> 497MB
# yogeshraheja/tomcatone  v1     <OLD_IMAGE_ID> 497MB

Run the new container on port 86:

docker run -d --name tomcat_custom -p 86:8080 yogeshraheja/tomcatone:v2

Now open http://<host>:86 to confirm you’re running Tomcat version 8.5.8.

Always verify that the Tomcat version you specify in --build-arg exists in the archive. Incorrect versions will cause the build to fail.

Links and References

Watch Video

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Demo Build Tomcat image

Table of Contents

Prerequisites

Clone the Repository

Reviewing the Dockerfile

Dockerfile Instruction Reference

Building and Running the Default Image

Building with a Custom Tomcat Version

Links and References

Watch Video

​Table of Contents

​Prerequisites

​Clone the Repository

​Reviewing the Dockerfile

​Dockerfile Instruction Reference

​Building and Running the Default Image

​Building with a Custom Tomcat Version

​Links and References

Watch Video

Table of Contents

Prerequisites

Clone the Repository

Reviewing the Dockerfile

Dockerfile Instruction Reference

Building and Running the Default Image

Building with a Custom Tomcat Version

Links and References