What is Talos?
Talos is a made up of a few pieces. The first piece is an API-driven, purpose-built OS, based on Linux. Its entire purpose is to host a Kubernetes cluster, so it is not a general purpose OS. The OS consists of the Linux kernel, a simplified init system, and a series of components that run in containers on the system, managing things like connections between the nodes, routes and networking, and serving APIs. It doesn't have SSH or a package manager. Instead, all of the management of Talos happens over an API.
The second piece of Talos is osctl: the command-line interface to manage your Talos-based Kubernetes cluster. It lets you do all of the basic system administration on your cluster. You can view process lists, download log files, and so forth. It's designed specifically to help you debug problems on the cluster during development and testing.
How is Talos different than CoreOS/RancherOS/Linuxkit?
Talos shares a lot of attributes with these systems, but there are some important differences. Talos integrates tightly with Kubernetes, and is not meant to be a general-purpose operating system. The most important difference is that Talos is fully controlled by an API via a gRPC interface, instead of an ordinary shell. We don't ship SSH, and there is no console access. Removing components such as these has allowed us to dramatically reduce the footprint of Talos, and in turn, improve a number of other areas like security, predictability, reliability, and consistency across platforms. It's a big change from how operating systems have been managed in the past, but we believe that API-driven OSes are the future.
Why no shell or SSH?
Since Talos is fully API-driven, all maintenance and debugging operations should be possible via the OS API. We would like for Talos users to start thinking about what a "machine" is in the context of a Kubernetes cluster. That is, that a Kubernetes cluster can be thought of as one massive machine, and the nodes are merely additional, undifferentiated resources. We don't want humans to focus on the nodes, but rather on the machine that is the Kubernetes cluster. Should an issue arise at the node level, osctl should provide the necessary tooling to assist in the identification, debugging, and remedation of the issue. However, the API is based on the Principle of Least Privilege, and exposes only a limited set of methods. We envision Talos being a great place for the application of control theory in order to provide a self-healing platform.
Why the name "Talos"?
Talos was an automaton created by the Greek God of the forge to protect the island of Crete. He would patrol the coast and enforce laws throughout the land. We felt it was a fitting name for a security focused operating system designed to run Kubernetes.