applications/docusaurus/asset/docs/services/kubernetes.md

sidebar_position

sidebar_position
1

Kubernetes (K3s)

Overview

We use K3s, a lightweight Kubernetes distribution, as our container orchestration platform.

Cluster Setup

Nodes

• Master Node: oracle-master

  • Control plane components
  • etcd database
  • ArgoCD installation

• Worker Nodes: mayne-worker-1, mayne-worker-2, etc.

  • Application workloads
  • Monitoring stack
  • Service deployments

Access

# SSH to master node
ssh oracle-master

# Use kubectl (requires sudo on master)
sudo kubectl get nodes
sudo kubectl get pods -A

Common Operations

View All Resources

# Get all namespaces
sudo kubectl get namespaces

# Get all pods in all namespaces
sudo kubectl get pods -A

# Get services
sudo kubectl get services -A

Check Application Status

# Check specific namespace
sudo kubectl get all -n <namespace>

# View pod logs
sudo kubectl logs -n <namespace> <pod-name>

# Describe pod for troubleshooting
sudo kubectl describe pod -n <namespace> <pod-name>

Managing Applications

Most applications are managed by ArgoCD, so manual kubectl operations are rarely needed.

# Check ArgoCD applications
sudo kubectl get applications -n argocd

# Force sync an application (if needed)
sudo kubectl patch application -n argocd <app-name> \
  -p '{"metadata": {"annotations": {"argocd.argoproj.io/refresh": "hard"}}}' \
  --type merge

Namespaces

Each service runs in its own namespace for isolation:

Namespace	Purpose
argocd	ArgoCD deployment
cert-manager	Certificate management
ingress-nginx	Ingress controller
monitoring	Prometheus, Grafana
gitea	Git service
vault	Secrets management

Storage

Storage Classes

• local-path: Default storage class
  • Uses local disk on worker nodes
  • Good for development and non-critical data

Persistent Volumes

# View PVCs
sudo kubectl get pvc -A

# View PVs
sudo kubectl get pv

Networking

Ingress

External traffic flows through nginx-ingress-controller:

Internet → nginx-ingress → Service → Pod

Services

• ClusterIP: Internal only (default)
• LoadBalancer: External access (rarely used)
• Ingress: HTTPS with custom domains

Troubleshooting

Pod Not Starting

# Check pod events
sudo kubectl describe pod -n <namespace> <pod-name>

# Check logs
sudo kubectl logs -n <namespace> <pod-name>

# Check previous container logs (if crashed)
sudo kubectl logs -n <namespace> <pod-name> --previous

Resource Issues

# Check node resources
sudo kubectl top nodes

# Check pod resources
sudo kubectl top pods -A

Network Issues

# Check services
sudo kubectl get svc -A

# Check ingress
sudo kubectl get ingress -A

# Test connectivity from a pod
sudo kubectl run -it --rm debug --image=nicolaka/netshoot --restart=Never -- /bin/bash

Best Practices

1. Use namespaces for logical separation
2. Set resource limits on all containers
3. Use health checks (readiness and liveness probes)
4. Label everything for better organization
5. Don't run as root (use securityContext)

Next Steps

• ArgoCD Setup
• Monitoring Stack