Why Orchestration?
Containerization has revolutionized deployment management for developers, offering unparalleled flexibility. However, as applications become more granular, managing their deployment becomes increasingly complex. Tasks such as scheduling container deployment, managing networking between containers, and resource allocation require orchestration.
Today’s applications must address a variety of challenges:
- Replication of components
- Load Balancing
- Auto Scaling
- Rolling Updates
- Logging across components
- Monitoring and health checking
- Service Discovery
- Security
Container Orchestration:
Container orchestration is the process of efficiently organizing and managing multiple containers within an environment. It automates deployment, management, scaling, and networking of containers across clusters, thereby streamlining operations. Enterprises dealing with hundreds or thousands of Linux®️ containers and hosts greatly benefit from container orchestration. Examples include Docker Swarm, ECS, Kubernetes, and Azure Service Fabric.
Certified Kubernetes Distributions:
Kubernetes, a leading container orchestration technology, offers various distributions catering to different needs:
- Cloud Managed: EKS by AWS, AKS by Microsoft, and GKE by Google
- Self Managed: OpenShift by Redhat and Docker Enterprise
- Local dev/test: MicroK8s by Canonical, Minikube
- Vanilla Kubernetes: The core Kubernetes project (bare metal), Kubeadm
- Special builds: K3s by Rancher, a lightweight Kubernetes distribution for edge devices
What is Kubernetes?
Kubernetes, often dubbed as the operating system for microservices applications, orchestrates the deployment and management of numerous containers in clustered environments. It supports diverse workloads, including stateless, stateful, and data-processing tasks. If an application can run in a container, it can thrive on Kubernetes.
Key Points:
- Originating from Greek, “Kubernetes” means helmsman or pilot, reflecting its role in guiding applications.
- It manages containerized applications and services, ensuring predictability, scalability, and high availability.
- Written in Golang, Kubernetes orchestrates computing, networking, and storage infrastructure.
- It simplifies application deployment, scales easily, and fosters efficient management.
History:
- 2003: Google develops The Borg System to manage large-scale container clusters.
- 2013: Docker revolutionizes computing, spurring container adoption.
- 2014: Google engineers create Kubernetes, an open-source orchestrator.
- 2015: Kubernetes 1.0 releases, leading to widespread adoption.
- 2016: Kubernetes gains mainstream acceptance, with supporting products like Minikube and Helm.
- 2017 onwards: Kubernetes emerges as the dominant orchestration system, with major cloud providers offering fully managed services.
Kubernetes: A Container Platform
Kubernetes serves as a
- Container platform
- Microservices platform
- Portable cloud platform
Why Kubernetes?
- Leveraging decades of Google’s experience in running containerized workloads.
- Vibrant open-source community and extensive feature set.
- Support from multiple OS and infrastructure vendors.
- Rapid feature releases and modern tooling, including CLI and REST API support.
Important Features of Kubernetes:
Kubernetes simplifies application deployment, offers rolling updates, enables service discovery, provides storage provisioning, facilitates load balancing and scaling, ensures self-healing for high availability, and supports DevOps practices.
Kubernetes vs. Docker:
Kubernetes complements Docker and isn’t a competitor to it. While Docker Swarm provides container orchestration, Kubernetes excels in scalability, auto-scaling, and rolling updates.
Kubernetes Architecture:
Kubernetes clusters comprise master and worker nodes:
- Master Node: Hosts control plane components and manages the cluster.
- Worker Nodes: Run containerized applications.
Master Node Components:
- API Server: Exposes a REST API for cluster management.
- Etcd: Stores cluster configuration and state information.
- Scheduler: Assigns pods to suitable worker nodes.
- Controller Manager: Ensures the cluster state matches the desired state.
Worker Node Components:
- Kubelet: Communicates with the master and manages pods.
- Container Runtime: Runs containers defined in workloads.
- Kubernetes Proxy Service: Routes network traffic to services.
- cAdvisor: Monitors resource usage and performance.
Kubernetes Objects:
Kubernetes employs various objects to manage applications, including Pods, Replication Controllers, Deployments, Services, StatefulSets, DaemonSets, Jobs, and CronJobs.
Kubernetes Pods:
- Pods are the smallest units in Kubernetes, representing running processes.
- Each pod contains one or more application containers and shared storage.
- Pods are ephemeral and don’t survive scheduling or node failures.
Replication Controllers and ReplicaSets:
- Controllers manage pod lifecycle, ensuring a specified number of replicas are running.
- ReplicaSets extend replication controllers, supporting set-based selectors.
Deployments:
- Deployments manage application instances, offering self-healing mechanisms and rolling updates.
Services:
- Services facilitate communication between components within and outside applications.
- They provide externally visible URLs to pods and enable loose coupling between microservices.
Ingresses:
- Ingresses provide HTTP load balancing and SSL termination, exposing services to the outside world.
StatefulSets:
- StatefulSets ensure data persistence and ordered pod naming, ideal for stateful applications like databases.
DaemonSets:
- DaemonSets ensure all nodes run specific pods, useful for system-level resources like monitoring.
Jobs and Cron Jobs:
- Jobs create pods to execute tasks, ensuring completion before termination.
- CronJobs run periodic jobs on schedules defined in Cron format.
In conclusion, Kubernetes revolutionizes container orchestration, providing a robust platform for deploying, managing, and scaling containerized applications with ease and efficiency.
-Thank you, happy coding !!
