Case file SS-01
Fleet IoT cloud modernisation
A phased route from a long-lived fleet platform to containerised AWS services, private data paths and controlled PKI certificate rotation.
- In deliveryECS migration and device certificate rotation
- 20-yearmonolith being decomposed without a big-bang cutover
The brief
The group operates a long-lived fleet platform whose application, database and device-trust concerns had grown together over two decades. The goal is not a cosmetic re-host. It is to create a cloud operating model that can evolve without interrupting the connected estate already in service.
The engagement is anonymised because delivery is active. This account describes the engineering shape of the work without naming the organisation, its products or confidential implementation details.
The constraint
A fleet migration has two timelines. Cloud workloads can move through ordinary release cycles; deployed devices and their certificates cannot all be upgraded at once. The platform therefore has to support old and new paths during transition, preserve trust, and leave evidence for the organisation’s compliance obligations.
That ruled out a big-bang rewrite. The migration was sequenced around reversible boundaries: cloud foundation, private data connectivity, container runtime, workload decomposition and certificate lifecycle.
The engineering approach
The target runtime uses ECS for independently deployable services and TimescaleDB behind private network boundaries for time-series workloads. Infrastructure is defined in OpenTofu and delivered through reviewed automation rather than manual console configuration.
PKI rotation is treated as a system capability, not a one-off maintenance event. The design separates issuer, policy, distribution, overlap and revocation concerns so certificates can move through controlled states while the fleet remains available. Rotation evidence and exception handling are part of the delivery path because a technically valid certificate change is not enough if it cannot be demonstrated later.
Shipped so far
The cloud foundation and private connectivity required by the migration are in place. The ECS workload transition and automated certificate-rotation path remain in delivery, progressed in stages so each boundary can be verified before the next is moved.
The practical outcome is a route off the monolith that respects the installed fleet: modernise the control plane first, coexist where necessary, and retire old paths only when production evidence supports it.