Kubernetes Architecture: Demystifying etcd Data Store.

The kubernetes API server is the gateway to the kubernetes cluster. This is the primary medium through which we interact with our cluster. The front end of the kubernetes control plane. It is also the medium of communication between resources on the control node and those on the worker node. Nothing escapes the Kube API server. All communication passes through it.

However, anybody who has worked with Kubernetes long enough knows that the API server is stateless. This is where etcd comes in. The etcd data store is where cluster configuration is stored. All configurations and secrets are persisted in the etcd data store in order to maintain state. While this is obvious, what is not so obvious is that extra steps must be taken, especially in a production environment, to protect this data and ensure its continuous availability. This etcd is deployed as a pod on the control node and has a its default data directory location in /var/lib/etcd.

This is why knowing how to backup and restore the etcd data store becomes important. For instance, you need to recover from an administrative error such as a delete operation in which you accidentally deleted the data store. Or perhaps, you lost the server in which etcd was being hosted. Knowing how to backup and restore your etcd server is a very important skill which you must add to your skillset.

For starters, etcdctl is the command line client for interacting with etcd. It also provides backup and restore capabilities for etcd data stores. When you backup etcd, it creates a backup file which will contain the complete state of the data stored in etcd. Etcdctl is not installed by default, so you may need to download it first. You can either download the binary from GitHub or you can run the image as a container.

Before making a backup of your etcd, you need to have a backup plan. When making a backup plan, there are a few factors you must consider. The first is encrypting your backup file. Since they are plain-text by default, you need to ensure that they are encrypted after backup. The second factor to consider is an offsite location for storing your backup file(s). You do not want to lose your backup file alongside your etcd data store if the server goes down or you lose access to your cluster.