Cloud Foundry Summit 2026

Building a CPI is not only a matter of implementing methods. It is a set of design choices about how BOSH expresses placement, identity, storage, networking, recovery, and operator intent on a specific platform.

We learned this while building a Proxmox VE CPI for Cloud Foundry BOSH. As part of that work, we studied six existing CPIs—AWS, Azure, Google, OpenStack, vSphere, and Alicloud—from their handler code, not just their documentation. We looked for the techniques each CPI uses to preserve the BOSH contract while adapting to its IaaS.

This session distills that work into a practical guide for CPI authors, platform engineers, and BOSH operators. We will compare the concepts every CPI must handle: placement, lifecycle identity, disk and stemcell management, networking, long-running operations, retry boundaries, rollback, hooks, observability, and operator controls.

Proxmox is the case study, but the talk is about CPI design. We will show how platform capabilities shape implementation choices, what belongs in the CPI, what belongs in the platform, and what should remain configurable.