Updating tomcat and nginx on Ubuntu and DigitalOcean

1. What is the problem? Be very detailed.

We want to update nginx and tomcat on our Digital Ocean droplet that hosts our data collection server. We have installed ODK Aggregate according to the documentation: https://docs.getodk.org/aggregate-digital-ocean/

Over time nginx and tomcat have become out of date, and in fact there are security reasons to update them. For example:

My question is if there are any pitfalls in updating this software? It is our data collection server, and it is OK if ODK Aggregate isn't running during the update. How do I make sure that ODK Aggregate is running again after everything is done?

Also, what tutorial / step-by-step procedure can I use?

2. What app or server are you using and on what device and operating system? Include version numbers.

  • DigitalOcean droplet
  • Ubuntu 18.04 LTS
  • ODK Aggregate

3. What you have you tried to fix the problem?

sudo apt update
sudo apt upgrade

This does not update nginx or tomcat since they are installed outside of Ubuntu's package repositories.

I'm asking this question so that I can avoid any pitfalls.

4. What steps can we take to reproduce the problem?

Could be reproduced on any Digital Ocean droplet

5. Anything else we should know or have? If you have a test form or screenshots or logs, attach below.