Molly Gloss's The Dazzle of the Day is set on a generation ship and is literally cozy, in that its main focus is the relationships within the community that makes up the ship's crew, the customs that govern their society, and the strain that life in space puts on both. As I recall the ship never even reaches its destination over the course of the book. But it's not properly a cozy since there's no criminal investigation, more like various eruptions of socially unacceptable behavior that the community's members and leadership have to figure out how to deal with.