HOWTO run Apache Tomcat on Opalstack

sean

Apache Tomcat is an open-source application server for Java apps that you can install on your Opalstack account with the procedure described below.

This procedure is adapted from one posted by @anjanesh at https://community.opalstack.com/d/699-tomcat-and-jdk/3 with the following updates:

Includes steps to install a newer version of Java
Includes a newer version of Tomcat
Updates the app configuration via sed instead of manually editing the config

Here we go:

Go to https://my.opalstack.com/apps/ and create a new "Nginx Proxy Port" app and make a note of the new app's port assignment.
Go to https://my.opalstack.com/domains/ and create a site to serve the app you created in step 1.

Log in to SSH as your app's shell user and run the following commands, replacing NAME_OF_YOUR_APP with the name of the app you created in step 1 and NNNNN with the app's assigned port.

mkdir ~/opt
cd ~/opt
wget https://download.oracle.com/java/21/latest/jdk-21_linux-x64_bin.tar.gz
tar zxf jdk-21_linux-x64_bin.tar.gz
ln -s jdk-21.0.5 java
export JRE_HOME=$HOME/opt/java
echo "export JRE_HOME=$JRE_HOME" >> ~/.bashrc
cd ~/apps/NAME_OF_YOUR_APP
wget https://dlcdn.apache.org/tomcat/tomcat-10/v10.1.33/bin/apache-tomcat-10.1.33.tar.gz
tar zxf apache-tomcat-10.1.33.tar.gz --strip 1
sed -i -e 's/"8080"/"NNNNN"/g' conf/server.xml
rm -rf logs
ln  -s $HOME/logs/apps/NAME_OF_YOUR_APP logs
~/apps/NAME_OF_YOUR_APP/bin/startup.sh

Tomcat should now be up and running at the URL of the site that you created in step 2 above. If it doesn't seem to be working then check the Tomcat logs in the app's logs subdirectory for possible problems and troubleshoot as appropriate.

The commands to start and stop the installed app are:

Start: ~/apps/NAME_OF_YOUR_APP/bin/startup.sh
Stop: ~/apps/NAME_OF_YOUR_APP/bin/shutdown.sh

Donzo

Here's a newer way to install Java JDKs and, if you must, Tomcat. Use SDKMAN.io. Root access is not needed since, by default, SDKMAN installs JDKs and SDKs in your home directory. You can install multiple versions or providers of JDKs and switch between them for different Java apps.

After completing the SDKMAN install steps, you can begin using SDKMAN to install JDKs and SDKs:

sdk install java 25.0.4-tem
sdk install tomcat

FYI, I'm investigating Java again after a long hiatus. It's a multi-billion dollar ecosystem paid for by the Enterprise guys and available to us peasants for free. It can be ridiculously fast compared to PHP or Python with similar memory footprints. For much lighter weight, lower memory, use Quarkus.io, not Spring Boot. If you need even lower memory footprints, Quarkus apps can be compiled with GraalVM into native Linux binaries. The Enterprise guys have spent many $millions on Quarkus to squeeze their apps into lower memory Kubernetes containers. The results of this also works well on hosting like Opalstack.