☁️ Containers and Kubernetes
Kubernetes basics are the fundamental concepts that explain how Kubernetes runs containers, keeps applications healthy, scales workloads, and abstracts infrastructure. Kubernetes is the evolution of virtualization: instead of managing VMs, you manage containerized workloads through declarative configuration and automated orchestration.
The concise takeaway: Kubernetes is a container orchestration platform that schedules, scales, heals, and exposes containerized applications.
🧩 What Kubernetes Actually Does
Section titled “🧩 What Kubernetes Actually Does”Kubernetes automates:
- Deployment
- Scaling
- Networking
- Storage
- Health checks
- Self‑healing
- Rolling updates
It treats infrastructure as a cluster and workloads as declarative objects.
🏗️ Core Kubernetes Architecture
Section titled “🏗️ Core Kubernetes Architecture”1. Cluster
Section titled “1. Cluster”A Kubernetes cluster consists of:
- Control Plane — API server, scheduler, controller manager
- Worker Nodes — run your containers
Nodes run the container runtime (containerd, CRI‑O) and the kubelet agent.
2. Pods
Section titled “2. Pods”The smallest deployable unit in Kubernetes.
A Pod contains:
- One or more containers
- Shared network namespace
- Shared storage volumes
Pods are ephemeral — Kubernetes replaces them automatically when needed.
3. Deployments
Section titled “3. Deployments”Deployments manage stateless applications.
They provide:
- Replica management
- Rolling updates
- Rollbacks
- Self‑healing
Deployments ensure your desired number of Pods always run.
4. Services
Section titled “4. Services”Services expose Pods to the network.
Types include:
- ClusterIP (internal)
- NodePort (external via nodes)
- LoadBalancer (cloud LB integration)
- Headless services (for stateful apps)
Services provide stable networking even when Pods change.
5. Ingress
Section titled “5. Ingress”Ingress manages HTTP/HTTPS routing into the cluster.
It supports:
- Path‑based routing
- Host‑based routing
- TLS termination
- Reverse proxying
Ingress controllers include NGINX, Traefik, HAProxy, and cloud‑native controllers.
6. ConfigMaps & Secrets
Section titled “6. ConfigMaps & Secrets”Configuration and sensitive data are stored separately from container images.
- ConfigMaps → non‑sensitive config
- Secrets → passwords, tokens, certificates
They are injected into Pods as environment variables or mounted files.
7. Volumes
Section titled “7. Volumes”Volumes provide persistent storage for Pods.
Types include:
- EmptyDir
- HostPath
- PersistentVolume (PV)
- PersistentVolumeClaim (PVC)
- Cloud storage (EBS, Azure Disk, GCP PD)
Stateful workloads use StatefulSets + persistent volumes.
8. StatefulSets
Section titled “8. StatefulSets”Used for stateful applications (databases, queues).
They provide:
- Stable network identities
- Ordered deployment
- Persistent storage binding
StatefulSets complement Deployments for workloads that require identity.
9. Namespaces
Section titled “9. Namespaces”Namespaces logically isolate resources.
Useful for:
- Multi‑team clusters
- Dev/Test/Prod separation
- RBAC boundaries
They help organize large clusters.
⚙️ How Kubernetes Works (The Control Loop)
Section titled “⚙️ How Kubernetes Works (The Control Loop)”Kubernetes uses a declarative model:
- You declare the desired state (e.g., 3 replicas).
- Kubernetes continuously compares desired vs actual state.
- Controllers reconcile differences automatically.
This is the core of Kubernetes automation.
🔐 Kubernetes Security Basics
Section titled “🔐 Kubernetes Security Basics”Security is enforced through:
- RBAC (Role‑Based Access Control)
- Network Policies
- Secrets encryption
- Pod Security Standards
- Service Accounts
Identity and access are central to cluster governance.
📈 Scaling & Self‑Healing
Section titled “📈 Scaling & Self‑Healing”Kubernetes automatically:
- Restarts failed Pods
- Replaces unhealthy nodes
- Scales workloads based on CPU/memory
- Distributes Pods across nodes
Horizontal Pod Autoscalers (HPA) and Vertical Pod Autoscalers (VPA) handle scaling.
🧪 Kubernetes in the Real World
Section titled “🧪 Kubernetes in the Real World”SysAdmins use Kubernetes for:
- Microservices
- API platforms
- Internal apps
- CI/CD pipelines
- Cloud‑native workloads
- Hybrid infrastructure
It’s the standard for container orchestration across AWS, Azure, GCP, and on‑prem (Kubernetes, AKS, EKS, GKE, OpenShift, Rancher).
📌 Summary
Section titled “📌 Summary”Kubernetes basics include:
- Clusters (control plane + nodes)
- Pods (containers)
- Deployments (stateless apps)
- StatefulSets (stateful apps)
- Services (stable networking)
- Ingress (HTTP routing)
- ConfigMaps/Secrets (configuration)
- Volumes/PVCs (storage)
- Namespaces (organization)
Kubernetes provides automated deployment, scaling, networking, and self‑healing for containerized applications.