Manage security and best-practices with policies.

Production-Grade Container Orchestration

The Kubernetes API server stores objects, relying on an etcd-compatible backing store (often, the backing storage is etcd itself). Each object is serialized using a particular version of that API type; for example, the v1 representation of a ConfigMap. Kubernetes uses the term storage version to describe how an object is stored in your cluster. The Kubernetes API also relies on automatic conversion; for example, if you have a HorizontalPodAutoscaler, then you can interact with that HorizontalPodAutoscaler using any mix of the v1 and v2 versions of the HorizontalPodAutoscaler API.

This page provides an overview of init containers: specialized containers that run before app containers in a Pod. Init containers can contain utilities or setup scripts not present in an app image. You can specify init containers in the Pod specification alongside the containers array (which describes app containers). In Kubernetes, a sidecar container is a container that starts before the main application container and continues to run. This document is about init containers: containers that run to completion during Pod initialization.

FEATURE STATE: Kubernetes v1.25 [stable] This page provides an overview of ephemeral containers: a special type of container that runs temporarily in an existing Pod to accomplish user-initiated actions such as troubleshooting. You use ephemeral containers to inspect services rather than to build applications. Understanding ephemeral containers Pods are the fundamental building block of Kubernetes applications. Since Pods are intended to be disposable and replaceable, you cannot add a container to a Pod once it has been created.

Use kubeconfig files to organize information about clusters, users, namespaces, and authentication mechanisms. The kubectl command-line tool uses kubeconfig files to find the information it needs to choose a cluster and communicate with the API server of a cluster. Note:A file that is used to configure access to clusters is called a kubeconfig file. This is a generic way of referring to configuration files. It does not mean that there is a file named kubeconfig.

Kubernetes volumes provide a way for containers in a pod to access and share data via the filesystem. There are different kinds of volume that you can use for different purposes, such as: populating a configuration file based on a ConfigMap or a Secret providing some temporary scratch space for a pod sharing a filesystem between two different containers in the same pod sharing a filesystem between two different pods (even if those Pods run on different nodes) durably storing data so that it stays available even if the Pod restarts or is replaced passing configuration information to an app running in a container, based on details of the Pod the container is in (for example: telling a sidecar container what namespace the Pod is running in) providing read-only access to data in a different container image Data sharing can be between different local processes within a container, or between different containers, or between Pods.

In Kubernetes, Services are an abstract way to expose an application running on a set of Pods. Services can have a cluster-scoped virtual IP address (using a Service of type: ClusterIP). Clients can connect using that virtual IP address, and Kubernetes then load-balances traffic to that Service across the different backing Pods. How Service ClusterIPs are allocated? When Kubernetes needs to assign a virtual IP address for a Service, that assignment happens one of two ways:

FEATURE STATE: Kubernetes v1.33 [stable](enabled by default) Sidecar containers are the secondary containers that run along with the main application container within the same Pod. These containers are used to enhance or to extend the functionality of the primary app container by providing additional services, or functionality such as logging, monitoring, security, or data synchronization, without directly altering the primary application code. Typically, you only have one app container in a Pod.

When using client certificate authentication, you can generate certificates manually through easyrsa, openssl or cfssl. easyrsa easyrsa can manually generate certificates for your cluster. Download, unpack, and initialize the patched version of easyrsa3. curl -LO https://dl.k8s.io/easy-rsa/easy-rsa.tar.gz tar xzf easy-rsa.tar.gz cd easy-rsa-master/easyrsa3 ./easyrsa init-pki Generate a new certificate authority (CA). --batch sets automatic mode; --req-cn specifies the Common Name (CN) for the CA's new root certificate. ./easyrsa --batch "--req-cn=${MASTER_IP}@`date +%s`" build-ca nopass Generate server certificate and key.