Launched by the European Commission in December 2021, under the sponsorship of Commissioner Thierry Breton, the European Alliance for Industrial Data, Edge and Cloud has the objectives of strengthening the position of the EU industry on cloud and edge technologies, and meeting the needs of EU businesses and public administrations that process sensitive categories of data. The Alliance brings together relevant stakeholders from the private and public sector to jointly define strategic investment roadmaps to enable the next generation of highly-secure, distributed, interoperable, and resource-efficient sovereign cloud and edge technologies. This talk will provide a summary of the role that open source plays in the EU technological roadmap that the Alliance will be publishing by the end of January 2023, and will explore the different ways in which collaboration around open source technologies can contribute to building a future European sovereign cloud.