Kubernetes (K8s)
An open-source system for automating deployment, scaling, and management of containerized applications.
Detailed Explanation
Kubernetes is the industry standard for container orchestration. It manages clusters of machines and decides where to run containers based on resource availability. It provides features like self-healing (restarting failed containers), load balancing, and zero-downtime rolling updates. It is the backbone of modern cloud-native infrastructure.
Quick Summary
Kubernetes orchestrates containers across a fleet of machines: scheduling, scaling, healing, and rolling updates. You declare the desired state with YAML, and the control plane works to make reality match.
Key Takeaways
- Declarative model: you describe what you want (3 replicas of this image), and controllers continuously reconcile actual state toward it.
- Core objects: Pod (group of containers), Deployment (manages Pods), Service (stable network endpoint), Ingress (HTTP routing).
- Self-healing: failed Pods are rescheduled automatically; failed nodes are drained and workloads moved.
- Horizontal Pod Autoscaler adjusts replica counts based on CPU, memory, or custom metrics.
- K8s is powerful but operationally heavy, for small teams, managed offerings (EKS, GKE, AKS) or simpler PaaS often beat self-hosting.
When to use it
- Running microservices at scale across many machines with built-in service discovery and load balancing.
- Batch and ML workloads via Jobs, CronJobs, and GPU node pools.
- Multi-tenant platforms where teams ship containers and the platform team manages the cluster.
- Hybrid and multi-cloud deployments using the same manifests across providers.
Common Mistakes
- Reaching for Kubernetes before it's needed; for a single small app, a VM or PaaS is usually a better fit.
- Skipping resource requests/limits, leading to noisy-neighbor outages and OOMKilled pods.
- Storing state in Pods instead of using PersistentVolumes or external databases, containers are ephemeral.
- Treating kubectl edit as the source of truth; manifests should live in git for IaC and audit.
Kubernetes (K8s), Frequently Asked
Do I need Kubernetes?
Probably not for one app or a small team. Kubernetes pays off when you have many services, heterogeneous workloads, or a platform-engineering team running the cluster. Otherwise the operational cost outweighs the benefits.
Kubernetes vs. Docker Swarm or Nomad?
Swarm is simpler but largely abandoned; Nomad is lighter and easier to operate but has a smaller ecosystem. Kubernetes wins on community, integrations, and managed offerings, pick alternatives only when its complexity is unjustified.
Should I self-host Kubernetes or use a managed service?
Managed services (EKS, GKE, AKS) handle the control plane, upgrades, and HA for you and are almost always the right choice. Self-hosting makes sense only when regulatory or air-gapped requirements force it.