tomevault-io Kubernetes (K8s) Developer Skill
Roadmap Alignment: roadmap.sh/kubernetes Reference: Kubernetes Official Docs | Kubectl Cheat Sheet
Context for Docker Users
Since you are familiar with Docker, here is how concepts translate to Kubernetes:
- Container → Pod (A pod is the smallest deployable unit and usually contains one container, sometimes more).
docker-compose.yml→ Manifests (Usually split into multiple YAML files likeDeployment,Service,ConfigMap).- Docker Volumes → PersistentVolume (PV) / PersistentVolumeClaim (PVC).
- Port Mapping (
-p 8080:80) → Service (Exposes your pods to the network). - Environment Variables (
.env) → ConfigMap (for non-sensitive data) and Secret (for sensitive data).
Core Standards & Best Practices
1. Declarative Configuration
- Always use YAML manifests and apply them via
kubectl apply -f file.yaml. - Avoid Imperative Commands: Do not use
kubectl createorkubectl runfor creating production resources. Keep everything version-controlled in Git (GitOps).
2. Workload Management
- Never create naked Pods. Always use a higher-level abstraction:
- Deployment: For stateless web servers, APIs, etc.
- StatefulSet: For databases or stateful applications requiring stable persistent storage.
- DaemonSet: For background agents running on every node (e.g., logging/monitoring).
- Job / CronJob: For one-off or scheduled batch tasks.
3. Resilience and Reliability
- Probes: Always configure
livenessProbe(restarts the pod if it crashes) andreadinessProbe(stops sending traffic to the pod if it's busy/starting up). - Resource Limits: Always define CPU and Memory
requests(what it needs to schedule) andlimits(maximum it can use). Without these, a memory leak in one pod can crash the entire node. - Replicas: Run at least 2 replicas for high availability, paired with a PodAntiAffinity rule to ensure they don't land on the same physical server.
4. Networking & Security
- Services: Use
ClusterIPfor internal communication. UseIngress(with a controller like NGINX) to expose HTTP/HTTPS traffic to the outside world, rather thanNodePortorLoadBalancer. - Namespaces: Use Namespaces to logically separate environments (e.g.,
dev,staging,prod) or different teams within the same cluster. - RBAC: Apply the principle of least privilege using Role-Based Access Control. Don't give pods administrative access to the K8s API unless absolutely necessary.
Common kubectl Commands for Docker Users
| Docker Command | Kubernetes Equivalent | Purpose |
|---|---|---|
docker ps |
kubectl get pods |
List running containers/pods |
docker logs -f <id> |
kubectl logs -f <pod-name> |
Tail logs |
docker exec -it <id> sh |
kubectl exec -it <pod-name> -- sh |
Open a shell inside |
docker stop <id> |
kubectl delete pod <pod-name> |
K8s will automatically restart it if managed by a Deployment |
Output Format
When generating Kubernetes YAMLs, ensure you use the apps/v1 (or current stable) API versions, include basic labels (app: [name]), and explain why certain blocks (like probes or limits) were included to help build intuition for K8s.
Source: jcchikikomori/skills-md — distributed by TomeVault.