Existing microservice architecture languages do not allow for the distinction and expression of intertwined cross-cutting architectural concerns, i.e. aspects that affect several microservices, without the possibility of being encapsulated in any of them. To address this problem, this paper proposes the Concern-Oriented Microservice Architecture metamodel where cross-cutting architectural concerns are first-class citizens and show how the worldwide-used Docker Compose language can be equipped with new concern-oriented constructions. This extension is applied to the TeaStore microservice reference application.