They do mention their OS being out of date. One possible interpretation is they are using packages provided by a Linux distro, and getting up to date may have required a full OS update.
If that's were case, it would be easy to see how they might want to tie their OS upgrade to a hardware refresh rather than taking servers offline for a reinstall.
When I was there NBNCo hadn't really moved into the inner city yet. We did have some kind of financial agreement with the building developer/management to install our VDSL DSLAMs in their comms room. It wouldn't surprise me if those payments got shadier and more aggressive as the NBN coverage increased.
To clarify, NBN is a monopoly on the last mile infrastructure which is resold to private ISPs that sell internet services.
The history there is that Australia used to have a government run monopoly on telephone infrastructure and services (Telecom Australia), which was later privatised (and rebranded to Telstra). The privatisation left Telstra with a monopoly on the infrastructure, but also a requirement that they resell the last mile at a reasonable rate to allow for some competition.
So Australia already had an existing industry of ISPs that were already buying last mile access from someone else. The NBN was just a continuation of the existing status quo in that regard.
> They even have a grey fibre box that looks identical to the NBNCo box except it's labelled LBNCo with the same font
Early in my career I worked for one of those smaller telcos trying to race to get services into buildings before the NBN. I left around the time they were talking about introducing an LBNCo brand (only one of the reasons I left). At the time, they weren't part of Opticomm, but did partner with them in a few locations. If the brand is still around, I guess they must have been acquired at some point.
I was a little confused about this as well - until I realised they don't actually specify that this is the Linux kernel. I suspect what they're talking about here is the Windows kernel.
In that case you would bundle a copy of the CLI utility into your docker container, with the correct version. This also applies to any system libraries your code might be compiled against. Things like shared libraries or CLI utilities are part of the "operating system", but not part of the "kernel".
This does mean that you end up with multiple copies of the same utilities and libraries on the system - although docker does have a mechanism to avoid duplication between different docker containers. It also means that if you take your docker container and move it over to a different system with a newer operating system (or a different distribution) all the parts of the operating system it cares about come with it.
The Linux kernel - the part that gets shared between containers - is mostly just responsible for process and memory management, networking and interacting with the computer hardware.
If that's were case, it would be easy to see how they might want to tie their OS upgrade to a hardware refresh rather than taking servers offline for a reinstall.