Ask HN: How do you version control your microservices?

When working on a project consisting of a large number of microservices, what solutions do you employ for controlling the composition of specific versions of each microservice. I currently use git submodules to track the application as a whole, with commit refs for each "green" version of microservice. This "master" repository is then tested with consumer driven contracts for each of the referenced submodules, with subsequent "green" masters for deployment to staging. This submodule approach requires a lot of discipline for small teams, and on more than one occasion we have encountered the usual submodule concerns. I'm concerned that this will only become more problematic as the team grows. What are your thoughts for a replacement process?