Write-up of how I build GeoServer from sources and deployed it to a locally installed Tomcat on my ThinkStation P320 Tower machine running `Ubuntu 20.04` (January 2026)

In late January 2026 I built GeoServer v2.28 from sources and deployed it to a local Apache Tomcat v9 servlet container on a Ubuntu 20.04 machine. The main steps were:

configuring the right version of javac to compile GeoServer with
installing the right version of Maven
installing (and troubleshooting) the installation of Tomcat

The guides I used were:

initial, top-level ChatGPT discussion outlining all steps (also archived here ).
It should be noted that, using this guide – and after manually upgrading Maven – I was able to compile Geoserver from sources, including all extensions using this incantation (as given in the guide):
```
$ mvn clean install -P allExtensions -DskipTests
```
If memory serves the tests were executing sort of nicely (with some warnings) but, in the end, I decided to skip them as they were taking far too long.
Guide on how to (manually) download and install Maven on Ubuntu . Also archived here . The reason this was necessary is that the version of GeoServer I wanted to install (v2.28) required a higher version of Maven than was available in the official Ubuntu repository for Ubuntu 20.04. If memory serves the former was 3.9 whereas the latter 3.6
Guide on how to manually install Apache Tomcat 9 on Ubuntu 20.04 . Also archived here . I followed this particular guide except only (if memory serves) changing the suggested installation location from: /opt/tomcat to: ~/software (a decision I've come to regret, not for any particular technical reason but solely for the fact that the alternative location I chose feels weird and is not normative).
It should also be noted that even though I configured the Uncomplicated Firewall with an additional rule, as suggested by the guide:
```
$ sudo ufw allow 8080
```
… this step (Step 6 in the guide) was moot in my case as I don't have the ufw firewall enabled on my system upon startup.

Following the instructions on the above guides resulted in Tomcat being unable to start properly so I then entered into a discussion with DeepSeek on how to troubleshoot the problem I was facing. This discussion is also archived here.

In the end, I ended up modifying the systemd/system Tomcat Unit file from:
the version originally suggested by guide #3
… to:
this.
The above changes also account for the fact that I'm using a different version of Java than the one suggested in guide #3.
A (sadly cropped) visual comparison (produced by Meld) is given in this screenshot.

After properly configuring the systemd Tomcat Unit file (/etc/systemd/system/tomcat.service), I was able to interact with Tomcat and examine its logs using such commands as the following:

$ sudo systemctl start tomcat.service # or just 'tomcat' in lieu of 'tomcat.service'
$ sudo systemctl stop tomcat.service
$ sudo systemctl status tomcat.service
$ sudo systemctl reload-or-restart tomcat.service
$ journalctl -f -u tomcat.service

In the end, I realized that for my purposes (local development / testing) I had gone to unnecessary lengths and suffered unnecessary pain to install Tomcat as a system-wide service with its own dedicated (pseudo-) user (plus it was less ergonomic to modify configuration files I had to sudo and such). It is indeed infinetely simpler (with zero complications) to just download the Tomcat tarball from the official site, explode it somewhere under my home directory and control it via the /bin/startup.sh and /bin/shutdown.sh scripts.

So after writing these lines my plan is to remove the tomcat user from my system and its associated systemd Unit files.

Regardless of the method of installing Tomcat I also encountered a CORS issue with GeoServer in the troubleshooting of which I lost a day and entered into a couple of discussions with two AIs (that went nowhere due to a red-herring) before finally realizing what it was all about and what was necessary. This record is kept in the repo of noteworthy AI discussions.