Pi Kubernetes Cluster
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K3S Kubernetes Cluster at home automated with Ansible and FluxCD
This is an educational project to build a hybrid x86/ARM Kubernetes cluster at home, using Raspberry Pi and refurbished x86 mini PCs, learn to deploy basic kubernetes services and automate its deployment and configuration applying IaC (infrastructure as a code) and GitOps methodologies.
The entire process for creating this cluster at home, from cluster design and architecture to step-by-step manual configuration guides, has been documented and it is published in the project website: https://picluster.ricsanfre.com.
This repository contains all source code used to automate all manual tasks described in the documentation: Cloud-init’s configuration files, Ansible’s source code (playbooks/roles), and packaged Kubernetes applications (helm and kustomize) to be deployed using FluxCD.
Since its deployment is completely automated, the cluster can be re-deployed in minutes as many times as needed for testing new cluster configurations, new software versions or just take you out of any mesh you could cause playing with the cluster.
Scope
The scope of this project is to build a hybrid x86/ARM kubernetes cluster at home, using low cost Raspeberry PIs and old refurbished mini PCs, and automate its deployment and configuration applying IaC (infrastructure as a code) and GitOps methodologies with tools like Ansible, OpenTofu / Terraform, cloud-init and Flux CD.
As part of the project, the goal is to use a lightweight Kubernetes flavor based on K3S and deploy cluster basic services such as:
- Distributed block storage for POD’s persistent volumes, LongHorn.
- S3 Object storage, RustFS.
- Backup/restore solution for the cluster, Velero and Restic.
- Certificate management, Cert-Manager.
- Secrets Management solution with Vault and External Secrets
- Identity Access Management(IAM) providing Single-sign On, Keycloak
- Observability platform based on:
- Metrics monitoring solution, Prometheus
Also deployment of services for building a cloud-native microservices architecture are include as part of the scope:
- Service mesh architecture, Istio
- API security with Oauth2.0 and OpenId Connect, using IAM solution, Keycloak
- Streaming platform, Kafka
Technology Stack
The following picture shows the set of opensource solutions used so far in the cluster, which installation process has been documented and its deployment has been automated with Ansible/FluxCD:
| Name | Description | |
|---|---|---|
| Ansible | Automate OS configuration, external services installation and k3s installation and bootstrapping | |
| FluxCD | GitOps tool for deploying applications to Kubernetes | |
| OpenTofu | Automate the provisioning of external services (Vault, DNS, S3 buckets, etc) required for the cluster operation | |
| Cloud-init | Automate OS initial installation | |
| Ubuntu | Cluster nodes OS | |
| OpenWRT | Router/Firewall OS | |
| K3S | Lightweight distribution of Kubernetes | |
| containerd | Container runtime integrated with K3S | |
 | Cilium | Kubernetes Networking (CNI) and Load Balancer |
| CoreDNS | Kubernetes DNS | |
| ExternalDNS | External DNS synchronization | |
| Kube-VIP | Kubernetes API Load-balancer | |
| Envoy Gateway | Kubernetes Gateway API Controller | |
| Longhorn | Kubernetes distributed block storage | |
| RustFS | S3 Object Storage solution | |
| Cert-manager | TLS Certificates management | |
| Hashicorp Vault | Secrets Management solution | |
| External Secrets Operator | Sync Kubernetes Secrets from Hashicorp Vault | |
| Keycloak | Identity Access Management | |
| Velero | Kubernetes Backup and Restore solution | |
| Restic | OS Backup and Restore solution | |
| Prometheus | Metrics monitoring and alerting | |
| Fluentd | Logs forwarding and distribution | |
 | Fluentbit | Logs collection |
| Loki | Logs aggregation | |
| Elasticsearch | Logs analytics | |
| Kibana | Logs analytics Dashboards | |
| Tempo | Distributed tracing monitoring | |
| Grafana | Monitoring Dashboards | |
| Istio | Kubernetes Service Mesh | |
| Strimzi Kafka | Kubernetes Operator for running Kafka streaming platform | |
| CloudNative PosgreSQL | Kubernetes Operator for running PosgreSQL | |
| MongoDB Kubernetes Operator | Kubernetes Operator for running MongoDB | |
| Valkey Operator | Kubernetes Operator for running Valkey (Redis-compatible memory database) |
Deprecated Technology
The following technologies have been used in previous releases of PiCluster but they have been deprecated and not longer maintained
| Name | Description | |
|---|---|---|
 | Metal-LB | Load-balancer implementation for bare metal Kubernetes clusters. Replaced by Cilium CNI load balancing capabilities |
| Traefik | Kubernetes Ingress Controller. Replaced by NGINX Ingress Controller | |
| ArgoCD | GitOps tool. Replaced by FluxCD | |
| Flannel | Kubernetes CNI plugin. Embedded into K3s. Replaced by Cilium CNI | |
| HAProxy | Kubernetes API Load-balancer. Replaced by Kube-VIP | |
| NGINX Ingress Controller | Kubernetes Ingress Controller. Replaced by Envoy Gateway | |
| OAuth2 Proxy | OAuth2.0 Proxy. Replaced by Envoy Gateway with OIDC integration with Keycloak | |
| MinIO | S3 Object Storage. Replaced by RustFS after progressive degradation of open-source community edition |
External Resources and Services
Even whe the premise is to deploy all services in the kubernetes cluster, there is still a need for a few external services/resources. Below is a list of external resources/services and why we need them.
Cloud external services
| Provider | Resource | Purpose | |
|---|---|---|---|
 | Letsencrypt | TLS CA Authority | Signed valid TLS certificates |
 | IONOS | DNS | DNS and DNS-01 challenge for certificates |
NOTE: These resources are optional, the homelab still works without them but it won’t have trusted certificates
Alternatives:
- Use a private PKI (custom CA to sign certificates).
Currently supported. Only minor changes are required. See details in Doc: Quick Start instructions. - Use other DNS provider.
Cert-manager / Certbot, which are the tools that automatically obtain certificates from Let’s Encrypt, can be configured to use other DNS providers. It will need further modifications in the way cert-manager application is deployed (new providers and/or webhooks/plugins might be required).
Currently only acme issuer (letsencytp) using IONOS as dns-01 challenge provider is configured. Check list of supported dns01 providers.
Self-hosted external services
There is another list of services that I have decided to run outside the kubernetes cluster, self-hosting them.
| External Service | Resource | Purpose | |
|---|---|---|---|
| RustFS | S3 Object Store | Cluster Backup | |
| Hashicorp Vault | Secrets Management | Cluster secrets management |
Vault and RustFS services are running in one of the cluster nodes, node1, to keep them locally accessible to the cluster and to avoid exposing them to the public internet.
Cluster architecture and hardware
Home lab architecture, showed in the picture below, consist of a Kubernetes cluster of ARM (Rasbperry PI) and x86 (HP elitedesk 800 G3 mini PCs) nodes and a firewall, built with another Raspberry PI, to isolate cluster network from your home network.
See further details about the architecture and hardware in the documentation
Official Site
You can browse more information about Pi Cluster Project on https://picluster.ricsanfre.com/.
The content of this website and the source code to build it (Jekyll static based website) are also stored in this repo: /docs folder.
Usage
Check out the documentation Quick Start guide to know how to use and tweak cloud-init files (/cloud-init folder), Ansible playbooks (/ansible folder) and packaged Kubernetes applications ( /kubernetes folder) contained in this repository, so you can use in for your own homelab.