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

Mon, 01 Jan 2024 09:00:00 -0400

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.

Using HashiCorp Vault as Ingress TLS Certificate Issuer in TAP

Mon, 01 Jan 2024 09:00:00 -0400

Using HashiCorp Vault as Ingress TLS Certificate Issuer in TAP

Tanzu Application Platform (TAP) uses Contour HTTPProxy resources to expose several web components externally via ingress. Some of these components include the API Auto Registration, API Portal, Application Live View, Metadata Store, and TAP GUI. Web workloads deployed through TAP also leverage the same method for their ingress resources. For example:

$ kubectl get httpproxy -A

NAMESPACE NAME FQDN TLS SECRET STATUS STATUS DESCRIPTION
api-auto-registration api-auto-registration-controller api-auto-registration.tap.cloudnativeapps.cloud api-auto-registration-cert valid Valid HTTPProxy
api-portal api-portal api-portal.tap.cloudnativeapps.cloud api-portal-tls-cert valid Valid HTTPProxy
app-live-view appliveview appliveview.tap.cloudnativeapps.cloud appliveview-cert valid Valid HTTPProxy
metadata-store amr-cloudevent-handler-ingress amr-cloudevent-handler.tap.cloudnativeapps.cloud amr-cloudevent-handler-ingress-cert valid Valid HTTPProxy
metadata-store amr-graphql-ingress amr-graphql.tap.cloudnativeapps.cloud amr-ingress-cert valid Valid HTTPProxy
metadata-store metadata-store-ingress metadata-store.tap.cloudnativeapps.cloud ingress-cert valid Valid HTTPProxy
tap-demo-01 spring-petclinic-contour-76691bbb1936a7b010ca900ce58a3f57spring spring-petclinic.tap-demo-01.svc.cluster.local valid Valid HTTPProxy
tap-demo-01 spring-petclinic-contour-88f827fbdc09abbb4ee2b887bba100edspring spring-petclinic.tap-demo-01.tap.cloudnativeapps.cloud tap-demo-01/route-a4b7b2c7-0a56-48b9-ad26-6b0e06ca1925 valid Valid HTTPProxy
tap-demo-01 spring-petclinic-contour-spring-petclinic.tap-demo-01 spring-petclinic.tap-demo-01 valid Valid HTTPProxy
tap-demo-01 spring-petclinic-contour-spring-petclinic.tap-demo-01.svc spring-petclinic.tap-demo-01.svc valid Valid HTTPProxy
tap-gui tap-gui tap-gui.tap.cloudnativeapps.cloud tap-gui-cert valid Valid HTTPProxy

TAP uses a shared ingress issuer as a centralized certificate authority representation, providing a method to set up TLS for the entire platform. All participating components get their ingress certificates issued by it. This is the recommended best practice for issuing ingress certificates on the platform.

Pki on Build. Run. Repeat.

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

Prerequisites

Setting Up HashiCorp Vault as Intermediate CA

Deploy Initialize and Configure Vault

Using HashiCorp Vault as Ingress TLS Certificate Issuer in TAP

Using HashiCorp Vault as Ingress TLS Certificate Issuer in TAP