Kubernetes – Bits of .NET

Kubernetes: Use ConfigMaps for Configuration

- 12.07.26 - ErcanOPAK comment

⚙️ ConfigMaps = Configuration Hardcoding config is bad. ConfigMaps externalize configuration. Change settings without rebuilding. 📝 Creating ConfigMaps # From literal values kubectl create configmap app-config \ –from-literal=env=production \ –from-literal=log-level=debug \ –from-literal=api-url=https://api.example.com # From file kubectl create configmap app-config \ –from-file=./configs/app.properties \ –from-file=./configs/log4j.properties # From YAML apiVersion: v1 kind: ConfigMap metadata: name: app-config data: env: […]

Kubernetes: Use Ingress Controllers for HTTP Routing

- 12.07.26 - ErcanOPAK comment

🚪 Ingress = HTTP Routing NodePort and LoadBalancer are basic. Ingress provides advanced HTTP routing. Single entry point, multiple services. 📝 Ingress Basics # Install NGINX Ingress Controller kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v1.8.1/deploy/static/provider/cloud/deploy.yaml # Ingress Resource apiVersion: networking.k8s.io/v1 kind: Ingress metadata: name: my-ingress spec: rules: – host: app.example.com http: paths: – path: / pathType: Prefix backend: […]

Kubernetes: Manage Storage with Persistent Volumes

- 12.07.26 - ErcanOPAK comment

💾 Persistent Volumes = Storage Management Data outlives pods. Persistent Volumes store data. PV, PVC, StorageClass — storage done right. 📝 PV and PVC # PersistentVolume (PV) apiVersion: v1 kind: PersistentVolume metadata: name: postgres-pv spec: capacity: storage: 10Gi volumeMode: Filesystem accessModes: – ReadWriteOnce persistentVolumeReclaimPolicy: Retain hostPath: path: /data/postgres # PersistentVolumeClaim (PVC) apiVersion: v1 kind: PersistentVolumeClaim […]

Kubernetes: Understand Service Discovery (DNS)

- 11.07.26 - ErcanOPAK comment

🌐 Service Discovery = DNS Services need to find each other. Service Discovery uses DNS. Automatic, built-in, easy. 📝 DNS Basics # Service DNS format service-name.namespace.svc.cluster.local # Example my-service.default.svc.cluster.local # Short form (same namespace) my-service # With port my-service.default.svc.cluster.local:8080 # Headless Service (No cluster IP) apiVersion: v1 kind: Service metadata: name: headless-service spec: clusterIP: None […]

Kubernetes: Use Pod Lifecycle Hooks

- 11.07.26 - ErcanOPAK comment

🔄 Pod Lifecycle Hooks Pods have lifecycle events. Lifecycle hooks run at specific times. Init, pre-stop, post-start. 📝 Hook Types apiVersion: v1 kind: Pod metadata: name: app spec: containers: – name: app image: myapp:latest lifecycle: postStart: exec: command: [“/bin/sh”, “-c”, “echo ‘Container started'”] preStop: exec: command: [“/bin/sh”, “-c”, “echo ‘Container stopping’ && sleep 5”] # […]

Kubernetes: Use Init Containers for Setup Tasks

- 11.07.26 - ErcanOPAK comment

⚙️ Init Containers = Setup Tasks Apps need setup before start. Init containers run before main containers. Database migrations, permissions, downloads. 📝 Init Container Basics apiVersion: v1 kind: Pod metadata: name: app-with-init spec: initContainers: – name: init-db image: busybox command: [‘sh’, ‘-c’, ‘echo “Initializing database…” && sleep 5’] – name: init-permissions image: busybox command: [‘sh’, […]

Kubernetes: Use CronJobs for Scheduled Tasks

- 10.07.26 - ErcanOPAK comment

⏰ CronJobs = Scheduled Tasks Regular tasks need automation. CronJobs schedule tasks in Kubernetes. Backups, cleanup, reports — automatic. 📝 CronJob Setup apiVersion: batch/v1 kind: CronJob metadata: name: daily-backup spec: schedule: “0 2 * * *” # Daily at 2 AM jobTemplate: spec: template: spec: containers: – name: backup image: alpine:latest command: – /bin/sh – […]

Kubernetes: Choose the Right Service Type

- 10.07.26 - ErcanOPAK comment

🔌 Service Types = How to Expose Apps Pods need access. Service types control exposure. ClusterIP, NodePort, LoadBalancer — choose right one. 📝 Service Types # ClusterIP (Default) apiVersion: v1 kind: Service metadata: name: internal-app spec: type: ClusterIP selector: app: myapp ports: – port: 80 targetPort: 8080 # NodePort apiVersion: v1 kind: Service metadata: name: […]

Kubernetes: Use HPA for Automatic Scaling

- 10.07.26 - ErcanOPAK comment

📈 HPA = Automatic Scaling Traffic changes constantly. Horizontal Pod Autoscaler scales automatically. More pods when needed, less when not. 📝 HPA Setup # Install metrics-server kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml # Verify metrics-server kubectl top pods kubectl top nodes # Create HPA apiVersion: autoscaling/v2 kind: HorizontalPodAutoscaler metadata: name: web-hpa spec: scaleTargetRef: apiVersion: apps/v1 kind: Deployment […]

Kubernetes: Set Resource Limits for Stability

- 09.07.26 - ErcanOPAK comment

⚖️ Resource Limits = Stability Pods can consume all resources. Resource limits ensure stability. CPU, memory — protect your cluster. 📝 Setting Limits apiVersion: v1 kind: Pod metadata: name: myapp spec: containers: – name: app image: myapp:latest resources: requests: memory: “64Mi” cpu: “250m” limits: memory: “128Mi” cpu: “500m” # Requests: Minimum guaranteed # Limits: Maximum […]

Kubernetes: Secure Your Cluster with Network Policies

- 09.07.26 - ErcanOPAK comment

🛡️ Network Policies = Cluster Security Default is allow all. Network Policies control traffic. Zero trust, micro-segmentation, security. 📝 Network Policy Basics # Deny all (Default deny) apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: deny-all spec: podSelector: {} policyTypes: – Ingress – Egress # Allow specific ingress apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-nginx spec: podSelector: […]

Kubernetes: Use PodDisruptionBudget for High Availability

- 09.07.26 - ErcanOPAK comment

🛡️ PodDisruptionBudget = High Availability Pods fail, nodes upgrade. PodDisruptionBudget ensures availability. Minimum pods running, safe operations. 📝 PDB Basics apiVersion: policy/v1 kind: PodDisruptionBudget metadata: name: app-pdb spec: minAvailable: 2 # Minimum 2 pods running selector: matchLabels: app: myapp — # Or use maxUnavailable apiVersion: policy/v1 kind: PodDisruptionBudget metadata: name: app-pdb spec: maxUnavailable: 1 # […]

Kubernetes: Use Operators for Automated Management

- 07.07.26 - ErcanOPAK comment

🤖 Operators = Automated Management Manual operations are error-prone. Operators automate complex applications. Database, monitoring, custom apps — self-healing. 📝 Popular Operators # Databases – Postgres Operator (Crunchy Data) – MySQL Operator (Oracle) – MongoDB Operator – Elasticsearch Operator – Redis Operator # Monitoring – Prometheus Operator – Grafana Operator – Datadog Operator # Infrastructure […]

Kubernetes: Use Ingress Controllers for HTTP Routing

- 07.07.26 - ErcanOPAK comment

🚪 Ingress = HTTP Routing NodePort and LoadBalancer are basic. Ingress provides advanced HTTP routing. Single entry point, multiple services, SSL. 📝 Ingress Basics # Install NGINX Ingress Controller kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v1.8.1/deploy/static/provider/cloud/deploy.yaml # Ingress Resource apiVersion: networking.k8s.io/v1 kind: Ingress metadata: name: my-ingress spec: rules: – host: app.example.com http: paths: – path: / pathType: Prefix […]

Kubernetes: Use Helm Charts for Package Management

- 07.07.26 - ErcanOPAK comment

📦 Helm = Kubernetes Package Manager Kubernetes YAML is repetitive. Helm packages Kubernetes apps. Templates, versioning, sharing — like apt/yum for K8s. 📝 Helm Commands # Install Helm curl https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-3 | bash # Add repositories helm repo add bitnami https://charts.bitnami.com/bitnami helm repo add stable https://charts.helm.sh/stable helm repo update # Search charts helm search repo nginx […]

Kubernetes: Use Persistent Volumes for Data Persistence

- 05.07.26 - ErcanOPAK comment

💾 Persistent Data in Kubernetes Pods are ephemeral. Data disappears. Persistent Volumes store data beyond pod life. Essential for databases, files, state. 📝 PV and PVC # PersistentVolume (PV) apiVersion: v1 kind: PersistentVolume metadata: name: postgres-pv spec: capacity: storage: 10Gi volumeMode: Filesystem accessModes: – ReadWriteOnce persistentVolumeReclaimPolicy: Retain hostPath: path: /data/postgres # PersistentVolumeClaim (PVC) apiVersion: v1 […]

Kubernetes: Use ConfigMaps for Configuration Management

- 05.07.26 - ErcanOPAK comment

⚙️ Centralized Configuration Hardcoding config is bad. ConfigMaps externalize configuration. Change settings without rebuilding. 📝 Creating ConfigMaps # From literal values kubectl create configmap app-config \ –from-literal=env=production \ –from-literal=log-level=debug \ –from-literal=api-url=https://api.example.com # From file kubectl create configmap app-config \ –from-file=./configs/app.properties \ –from-file=./configs/log4j.properties # From directory kubectl create configmap app-config \ –from-file=./configs/ # From YAML apiVersion: […]

Kubernetes: Use Secrets to Store Sensitive Data Securely

- 05.07.26 - ErcanOPAK comment

🔐 Secure Secrets Management Passwords, tokens, keys — never hardcode. Kubernetes Secrets store sensitive data securely. Use in pods via environment variables or volumes. 📝 Creating Secrets # Create from literal values kubectl create secret generic app-secret \ –from-literal=db-password=SecurePass123 \ –from-literal=api-key=abc-123-xyz # Create from file kubectl create secret generic app-secret \ –from-file=./secrets/db-password.txt \ –from-file=./secrets/api-key.txt # […]

Kubernetes: Use Service Mesh (Istio) for Advanced Traffic Management

- 04.07.26 - ErcanOPAK comment

🚦 Advanced Traffic Management for Microservices Service Mesh adds features to Kubernetes. Istio provides traffic routing, load balancing, security, observability. 📝 Install Istio # Download Istio curl -L https://istio.io/downloadIstio | sh – cd istio-1.20.0 export PATH=$PWD/bin:$PATH # Install Istio istioctl install –set profile=demo -y # Enable sidecar injection kubectl label namespace default istio-injection=enabled # Deploy […]

Kubernetes: Use PodDisruptionBudget for Zero Downtime

- 04.07.26 - ErcanOPAK comment

🛡️ Prevent Simultaneous Pod Evictions Node draining can evict all pods at once. PodDisruptionBudget ensures minimum availability during disruptions. 📝 PDB Example apiVersion: policy/v1 kind: PodDisruptionBudget metadata: name: app-pdb spec: minAvailable: 2 selector: matchLabels: app: myapp — apiVersion: policy/v1 kind: PodDisruptionBudget metadata: name: app-pdb spec: maxUnavailable: 1 selector: matchLabels: app: myapp 🎯 PDB Status # […]

Kubernetes: Use StatefulSets for Stateful Applications

- 04.07.26 - ErcanOPAK comment

Kubernetes: Use HPA to Auto-Scale Pods Based on Load

- 24.06.26 - ErcanOPAK comment

📈 Scale Pods Automatically Fixed replicas waste resources. HorizontalPodAutoscaler scales pods based on CPU/memory. Scale up during load, down during low traffic. 📝 HPA Configuration apiVersion: autoscaling/v2 kind: HorizontalPodAutoscaler metadata: name: myapp-hpa spec: scaleTargetRef: apiVersion: apps/v1 kind: Deployment name: myapp minReplicas: 2 maxReplicas: 10 metrics: – type: Resource resource: name: cpu target: type: Utilization averageUtilization: […]

Kubernetes: Use DaemonSets to Run Pods on Every Node

- 24.06.26 - ErcanOPAK comment

📡 One Pod Per Node — Automatically Need monitoring agent on every node? Log collector? DaemonSet runs one pod per node. New nodes get pod automatically. 📝 DaemonSet Example apiVersion: apps/v1 kind: DaemonSet metadata: name: node-monitor namespace: kube-system spec: selector: matchLabels: name: node-monitor template: metadata: labels: name: node-monitor spec: containers: – name: monitor image: prom/node-exporter […]

Kubernetes: Use StorageClasses for Dynamic Volume Provisioning

- 24.06.26 - ErcanOPAK comment

💾 StorageClasses Create Volumes Automatically Manual volume creation is tedious. StorageClasses provision volumes dynamically. Specify storage type, size, performance. 📝 StorageClass Examples apiVersion: storage.k8s.io/v1 kind: StorageClass metadata: name: fast-ssd provisioner: kubernetes.io/aws-ebs parameters: type: gp3 encrypted: “true” iopsPerGB: “50” allowVolumeExpansion: true — apiVersion: storage.k8s.io/v1 kind: StorageClass metadata: name: standard provisioner: kubernetes.io/aws-ebs parameters: type: gp2 encrypted: “true” […]

Kubernetes: Use Node Affinity to Control Pod Placement

- 21.06.26 - ErcanOPAK comment

🎯 Put Pods Where They Belong Some nodes have GPUs. Some are in different zones. Node affinity schedules pods on specific nodes. Control placement precisely. 📝 Node Affinity apiVersion: v1 kind: Pod metadata: name: gpu-pod spec: affinity: nodeAffinity: requiredDuringSchedulingIgnoredDuringExecution: nodeSelectorTerms: – matchExpressions: – key: gpu operator: In values: – “nvidia” – “amd” containers: – name: […]

Kubernetes: Extend Kubernetes with Custom Resource Definitions

- 21.06.26 - ErcanOPAK comment

🔌 Define Your Own Kubernetes Objects Kubernetes has Pods, Services, Deployments. Custom Resource Definitions (CRD) create your own objects. Extend Kubernetes for your needs. 📝 Create a CRD apiVersion: apiextensions.k8s.io/v1 kind: CustomResourceDefinition metadata: name: databases.myapp.com spec: group: myapp.com versions: – name: v1 served: true storage: true schema: openAPIV3Schema: type: object properties: spec: type: object properties: […]

Kubernetes: Use Service Accounts for Pod Authentication

- 21.06.26 - ErcanOPAK comment

Kubernetes: Use Security Context to Control Pod Permissions

- 20.06.26 - ErcanOPAK comment

🔐 Run Containers as Non-Root User Containers run as root by default. Security context runs as non-root. Less privilege, better security. 📝 Security Context apiVersion: v1 kind: Pod metadata: name: secure-pod spec: securityContext: runAsUser: 1000 runAsGroup: 3000 fsGroup: 2000 containers: – name: myapp image: myapp:latest securityContext: allowPrivilegeEscalation: false readOnlyRootFilesystem: true capabilities: drop: [“ALL”] add: [“NET_ADMIN”] […]

Kubernetes: Use Persistent Volumes for Data Storage

- 20.06.26 - ErcanOPAK comment

💾 Pods Are Ephemeral. Data Shouldn’t Be. Pod restarts lose data. Persistent Volumes (PV) store data outside pods. Databases, uploads, logs survive restarts. 📝 Persistent Volume Claim apiVersion: v1 kind: PersistentVolumeClaim metadata: name: postgres-pvc spec: accessModes: – ReadWriteOnce resources: requests: storage: 10Gi storageClassName: standard — apiVersion: v1 kind: Pod metadata: name: postgres spec: containers: – […]

Kubernetes: Understand Service Types — ClusterIP, NodePort, LoadBalancer

- 20.06.26 - ErcanOPAK comment

🌐 Internal vs External Access Pods have IPs, but they change. Services provide stable access. Choose the right type: ClusterIP (internal), NodePort (external on node IP), LoadBalancer (cloud load balancer). 📝 Service Types ClusterIP (default): – Internal cluster access only – Virtual IP accessible inside cluster – Use for microservices communicating internally apiVersion: v1 kind: […]

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