The challenges were among others primarily scalability and costs. The scalability problem was not so much due to peaks or extra load. It was a high-availability, auto-scaling and continuous delivery for production without downtime challenge! Costs were considerably due to the usage of a managed private cloud, new services/changes/maintenance for example networking, patches, back-ups en restore fell under the hosting provider and were billed.
Tech challenges: how to set up the “monolith” in such a modular way that we can grow to a microservices architecture in the future if needed. Another challenge is how we can migrate the production platform to another cloud without a lift-and-shift.