Container runtimes allocate network namespaces for containers deployed on the host. A network interface (like docker0, bridge, or host) is configured inside the namespace to facilitate the communication with host, the internet, or other containers. The Container Network Interface (CNI) project provides specifications and libraries for implementing a plugin-based solution for managing network interfaces for containers. The runtime executes the CNI plugins provided as binary executable files. A network configuration is passed to the runtime as a JSON file....

Package managers like dnf and apt increase the convenience of installing, updating, and maintaining applications on operating systems. For developers, a package manager provides a standardized way of packaging and distributing their applications. Helm is a package manager for Kubernetes. It is implemented in Go and installed as a binary helm. It interacts with the Kubernetes cluster using Kubernetes API. Charts Helm distributes Kubernetes-based applications in a format called Chart....

An Operator Bundle Image (OBI) is created to package custom resources and metadata associated with an operator. It’s like any other container image only difference is that it couldn’t be executed but it could be distributed through an OCI-compliant image registry. Contents of a bundle image are: Kubernetes Custom Resource Definitions (CRDs) ClusterServiceVersion (CSV) Specification of operator’s dependencies Operator metadata like its name, version, channels, etc. The control loops associated with the operator are defined in its Controller Manager....

OpenShift provides an Operators section in its web console UI for the installation and management of operators on the cluster. OperatorHub The OperatorHub is an interface for searching and installing operators. It has the following categories of operators: Red Hat Operators: Operators developed and supported by Red Hat. Example: Red Hat Quay Operator Certified Operators: Operators listed by Red Hat’s Independent Software Vendors (ISVs). Example: CockroachDB Operator Red Hat Marketplace Operators: Applications purchased from Red Hat Marketplace available as Operators....

Applications built to be deployed on Kubernetes could be packaged as Operators. Operators automate the process of installation, updates, and management of the application. These automations are defined by developers based on the application’s business logic. An Operator consists of: Custom Resources (CRs) required by the application Custom controller for managing these CRs Control Loop A control loop is an infinite loop for monitoring the state of a system....