BOSH is an open-source software project that offers a toolchain for release engineering, software deployment and application lifecycle management of large-scale distributed services.
BOSH is a project that unifies release engineering, deployment, and lifecycle management of small and large-scale cloud software. BOSH can provision and deploy software over hundreds of VMs. It also performs monitoring, failure recovery, and software updates with zero-to-minimal downtime.
It is an open source software project written in Ruby, Go and Bash and one of the core component of Cloud Foundry.BOSH and its IaaS-specific Cloud Provider Interfaces (CPIs) are what let PCF run on multiple IaaSes.
Reference :