Setting up etcd certificates for RBAC

When using etcd it is a good idea to protect the data stored there. This is even more true when you have multiple components using a common etcd cluster. This set of tutorials guide you through the process of locking down and segmenting access to the data in your etcd datastore.

Why you might be interested in this guide

  • You want to restrict the operations that support staff are able to perform to minimize accidental corruption or deletion of etcd data.
  • You want to use a single etcd cluster for Calico and Kubernetes (rather than having an etcd cluster for Calico and a separate etcd cluster for Kubernetes.
  • You want to restrict the read/write access of the various Calico components as an additional safety measure.

Configuration Concept

The central piece that will link the components together is the Certificate Authority(CA). It will be used to generate certificates and keys that the etcd members (and proxies) and components (like Calico and Kubernetes) will need to authenticate with the etcd cluster. Because all the certificates will be generated from the same CA and all the components will have the CA certificate, they can authenticate their connections with each other.

The certificates and keys generated for the components accessing etcd will allow access to particular key prefixes or paths in etcd. The certificates are linked with an etcd username by being generated with a Common Name (CN) that matches the etcd username. The etcd username is linked with a role or multiple roles that allow access to the appropriate data in etcd.

Requirements

  • If using only the v2 API with etcd, as Calico does, then the minimum etcd version required is 3.0.12.
  • If using the v3 API with etcd, as Kubernetes can, then the minimum etcd version required is 3.2. (Note: The 3.x version of etcd supports both the v2 and the v3 API.)

Setup

  1. Generate CA, certificates, and keys.
  2. Setup etcd with the CA cert and the certificates generated in step 1. See the etcd security op-guide for help configuing etcd.
  3. Create Users and Roles in etcd.
  4. Configure components. For example: