Deploy challenges in real life

This is a small chapter to give a bit more background on the 'why show the end result' in this training with 2 repos and deviate from the deployment training on 2025.training.plone.org. It should also help the reader to maybe go to that training instead.

The 2025 training is still better suited to show a clean 'lab setup' for your first deployment to a containerised hosting setup. We could update the training to offer a separate 'get your own VM' instead of using a trainer provided tangrama.com.br setup. One of the realities of mid 2026 is that a VM with 8 GB RAM costs more than 40 euro/month, compared to 7 euro/month in 2025.

A first source of extra challenges comes from going to a multi-node swarm cluster, where the backend/frontend runs on separate worker nodes, and we should place the postgresql container on a fixed 'storage' node. These are essential multi-node containerisation skills to teach.

A second source of complexity comes from deploying more than one project to a cluster. The dynamic Traefik configuration using labels that get picked up when a service deploys, provides endless sources of collision fun, when you forget to point your frontend's RAZZLE_INTERNAL_API_PATH at stackname_backend instead of backend. This is also valid for the Traefik label namespaces where all routes, middlewares and services need to be unique in the cluster. We accomplish this through a STACK_PREFIX in a fully parameterised Docker Swarm stack template.

Then GitLab has its own deviations from easier or more common GitHub configurations. This version of the training has been tested a few times now. Letting students stumble over these challenges during the training, rather than later when they try to extend the setup, is very valuable.