Kubernetes Patterns

Kubernetes is a container orchestration platform that forms the foundation of other platforms built on top of it.

Kubernetes is a container orchestration platform that forms the foundation of other platforms built on top of it. Distributed primitives. Kubernetes introduces a new set of distributed primitives for building cloud-native applications. These include Pods (groups of containers), Services (for networking and load balancing), and various controllers for managing application lifecycle. These primitives provide a higher level of abstraction compared to traditional in-process building blocks, allowing developers to focus on application logic rather than infrastructure concerns. Declarative approach. Kubernetes adopts a declarative model where developers specify the desired state of their applications, and the platform continuously works to maintain that state. This approach simplifies application management and enables automated healing and scaling. Key Kubernetes concepts include: Containers: Packaged, isolated units of application code and dependencies Pods: The smallest deployable units, consisting of one or more containers Services: Stable network endpoints for accessing groups of Pods Labels and Annotations: Metadata for organizing and selecting resources Namespaces: Virtual clusters for resource isolation and multi-tenancy

To be fully automatable, a cloud-native application must be highly observable by allowing its state to be inferred so that Kubernetes can detect whether the application is up and whether it is ready to serve requests. Predictable Demands. Applications should declare their resource requirements and runtime dependencies. This enables Kubernetes to make intelligent decisions about placement and scaling. Key aspects include: Resource Profiles: Specifying CPU and memory requests and limits Quality of Service (QoS) classes: Best-Effort, Burstable, and Guaranteed Pod Priority: Indicating the relative importance of Pods Declarative Deployment. Kubernetes provides mechanisms for updating applications with minimal downtime: Rolling updates: Gradually replacing old Pods with new ones Blue-Green deployments: Switching traffic between two versions Canary releases: Gradually increasing traffic to a new version Health Probes and Managed Lifecycle. Applications should implement health checks and respond to lifecycle events: Liveness probes: Detecting if an application is running Readiness probes: Determining if an application is ready to serve traffic Lifecycle hooks: Responding to start and stop events

The Singleton Service pattern ensures only one instance of an application is active at a time and yet is highly available. Job Management. Kubernetes provides abstractions for managing different types of workloads: Batch Jobs: For running finite, completable tasks Periodic Jobs (CronJobs): For scheduled, recurring tasks Daemon Services: For running system-level services on every node Stateful Services. Kubernetes offers StatefulSets for managing applications that require stable network identities and persistent storage: Ordered deployment and scaling Stable network identities Persistent storage per Pod Service Discovery. Kubernetes provides multiple mechanisms for service discovery: ClusterIP Services: For internal communication NodePort and LoadBalancer Services: For external access Ingress: For…