  Edge computing seeks to enable applications with strict latency requirements
by utilizing compute resources deployed closer to the users. The diverse,
dynamic, and constrained nature of edge infrastructures necessitates a flexible
orchestration framework that dynamically supports application QoS requirements.
However, existing state-of-the-art orchestration platforms were designed for
datacenter environments and make strict assumptions about underlying
infrastructures that do not hold for edge computing. This work proposes a novel
hierarchical orchestration framework specifically designed for supporting
service operation over edge infrastructures. Through its novel federated
cluster management, delegated task scheduling, and semantic overlay networking,
our system can flexibly consolidate multiple infrastructure operators and
absorb dynamic variations at the edge. We comprehensively evaluate our
proof-of-concept implementation -- Oakestra -- against state-of-the-art
solutions in both controlled and realistic testbeds and demonstrate the
significant benefits of our approach as we achieve approximately 10x and 30%
reduction in CPU and memory consumption, respectively.
