The goal of the Open Search Foundation is to establish a decentralized open search infrastructure for navigating, searching, and analyzing the internet. Due to the variety of requirements, the need for a robust and extensible architecture arises. This paper gives first thoughts on an architecture for such an infrastructure. As a starting point, a basic architecture for a Data-Lake-based document-centric search engine is proposed. Afterwards, components are added and extended to meet further requirements of the envisaged search infrastructure.