Managing Kubernetes

Chapter 4. The Kubernetes API Server

As mentioned in the overview of the Kubernetes components, the API server is the gateway to the Kubernetes cluster. It is the central touch point that is accessed by all users, automation, and components in the Kubernetes cluster. The API server implements a RESTful API over HTTP, performs all API operations, and is responsible for storing API objects into a persistent storage backend. This chapter covers the details of this operation.

Basic Characteristics for Manageability

For all of its complexity, from the standpoint of management, the Kubernetes API server is actually relatively simple to manage. Because all of the API server’s persistent state is stored in a database that is external to the API server, the server itself is stateless and can be replicated to handle request load and for fault tolerance. Typically, in a highly available cluster, the API server is replicated three times.

The API server can be quite chatty in terms of the logs that it outputs. It outputs at least a single line for every request that it receives. Because of this, it is critical that some form of log rolling be added to the API server so that it doesn’t consume all available disk space. However, because the API server logs are essential to understanding the operation of the API server, we highly recommend that logs be shipped from the API server to a log aggregation service for subsequent introspection and querying to debug user or component requests to the ...