HashiCorp Vault Intermediate CA Setup with Cert-Manager and Microsoft Root CA

In this post, we’ll explore how to set up HashiCorp Vault as an Intermediate Certificate Authority (CA) on a Kubernetes cluster, using a Microsoft CA as the Root CA. We’ll then integrate this setup with cert-manager, a powerful Kubernetes add-on for automating the management and issuance of TLS certificates.

The following is an architecture diagram for the use case I’ve built.

• A Microsoft Windows server is used as the Root CA of the environment.
• A Kubernetes cluster hosting shared/common services, including HashiCorp Vault. This is a cluster that can serve many other purposes/solutions, consumed by other clusters. The Vault server is deployed on this cluster and serves as an intermediate CA server, under the Microsoft Root CA server.
• A second Kubernetes cluster hosting the application(s). Cert-Manager is deployed on this cluster, integrated with Vault, and handles the management and issuance of TLS certificates against Vault using the ClusterIssuer resource. A web application, exposed via ingress, is running on this cluster. The ingress resource consumes its TLS certificate from Vault.

Prerequisites

• Atleast one running Kubernetes cluster. To follow along, you will need two Kubernetes clusters, one serving as the shared services cluster and the other as the workload/application cluster.
• Access to a Microsoft Root Certificate Authority (CA).
• The Helm CLI installed.
• Clone my GitHub repository. This repository contains all involved manifests, files and configurations needed.

Setting Up HashiCorp Vault as Intermediate CA

Deploy Initialize and Configure Vault

Install the Vault CLI. In the following example, Linux Ubuntu is used. If you are using a different operating system, refer to these instructions.

Streamlining and Customizing Windows Image Builder for TKG

Tanzu Kubernetes Grid (TKG) is one of the few platforms providing out-of-the-box support and streamlined deployment of Windows Kubernetes clusters. VMware is actively investing in this area and constantly improving the support and capabilities around Windows on Kubernetes.

Unlike Linux-based clusters, for which VMware provides pre-packaged base OS images (typically based on Ubuntu and Photon OS), VMware cannot offer Windows pre-packaged images, primarily due to licensing restrictions, I suppose. Therefore, building your own Windows base OS image is one of the prerequisites for deploying a TKG Windows workload cluster. Fortunately, VMware leverages the upstream Image Builder project - a fantastic collection of cross-provider Kubernetes virtual machine image-building utilities intended to simplify and streamline the creation of base OS images for Kubernetes.

Tanzu Kubernetes Grid GPU Integration

I recently had to demonstrate Tanzu Kubernetes Grid and its GPU integration capabilities. Developing a good use case and assembling the demo required some preliminary research.

During my research, I reached out to Jay Vyas, staff engineer at VMware, SIG Windows lead for Kubernetes, a Kubernetes legend, and an awesome guy in general. :) For those who don’t know Jay, he is also one of the authors of the fantastic book Core Kubernetes (look it up!).