The rapid development and commercial adoption of the Internet of Things (IoT) has led to ubiquitous presence of relatively powerful and network-connected devices at the network Edge. Software running on such Edge infrastructures installed at customers' premises and acting as network gateways is often required to be updated, for example, to react to emerging business requirements, contextual changes or sudden security threats. The amount of effort required to deploy and operate software components at the Edge-i.e. to perform fleet management-grows proportionally to the size and complexity of the IoT fleet, and goes beyond manual capabilities of IoT vendors, aiming to achieve economies of scale. Addressing this challenge has become possible with the recent advances in the containerisation technology supported by IoT Cloud platforms, which offered IoT vendors an automated way to deploy and manage software components at scale. Accordingly, this paper focuses on this emerging technological domain and provides an overview of the current baseline, existing challenges, and future trends.