Using secrets stored in Key Vault
In the previous section, we explored secrets that were stored natively in Kubernetes. This means they were stored base64-encoded on the Kubernetes API server (in the background, they will be stored in an etcd database, but that is part of the managed service provided by Microsoft). We saw in the previous section that base64-encoded secrets are not secure at all. For highly secure environments, you will want to use a better secret store.
Azure offers an industry-compliant secrets storage solution called Azure Key Vault. It is a managed service that makes creating, storing, and retrieving secrets easy, and offers good monitoring of access to your secrets. Microsoft maintains an open-source project that allows you to mount secrets in Key Vault to your application. This solution is called Key Vault FlexVolume and is available here: https://github.com/Azure/kubernetes-keyvault-flexvol.
In this section, we will create a Key Vault and install Key Vault...