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K3S Riotkit Cluster "Space Harbor"

DANGER: This project is highly in WORK IN PROGRESS state. Subscribe this repository for releases if you want to be notified. We will release soon.

Creates a lightweight, opinionated single-node or multi-node cluster managed fully by ArgoCD. Requires write access to GIT repository.

GitOps flow

GitOps flow

GitOps flow

GitOps flow

How it is installed

Installation flow

Proposed VPN setup

This Ansible setup can handle multiple setups:

  • One primary, no any compute nodes
  • One primary + multiple compute nodes in same network without VPN
  • One primary + multiple compute nodes exposed via WireGuard VPN remotely

VPN setup

Architecture

Provided by K3S:

  • CoreDNS + Flannel: Networking
  • Canal: Network Policies
  • Embedded service load balancer (Rancher's Klipper Load Balancer)
  • SQLite3 (can be replaced with etcd, there is a migration possibility)

Of choice:

  • Cluster management: ArgoCD Core connected with a single "cluster-wide" GIT repository. Components synchronized on-click
  • Gateway: Traefik + Let's Encrypt (lightweight comparing to NGINX + cert-manager)
  • Health checks: Infracheck - health checks provided via HTTPS endpoint for external monitoring service (e.g. UptimeRobot), very lightweight comparing to Kuberhealthy
  • Metrics: Telegraf, passing-through to centralized Telegraf instance over TLS authentication (own CA)
  • Secrets management: https://github.com/bitnami-labs/sealed-secrets (lighttest solution possible, no maintenace except key backup)
  • SMTP relay: https://artifacthub.io/packages/helm/docker-postfix/mail
  • Backup: Backup Maker (part of Backup Repository)
  • WireGuard VPN (if wanting to use VPN, kernel-level VPN, fastest and most secure, easy to setup and manage)

Most of the above components can be disabled in Ansible vars. Selection criterias: lightweight, security, easy to setup

Security

Kubernetes API is private, accessible only on localhost:6443 and via VPN. ArgoCD is accessible on a public domain behind basic auth.

Target security considerations

  1. Access Cluster via VPN
  2. Use Network Policies to limit egress and ingress traffic
  3. Access ArgoCD management panel on local machine using ArgoCLI instead of exposing service to the internet

Pre-setup of networking

Notice: for clusters that are placed in different places on the world. Requirement: Python 3 and pip command

  1. Make sure you do not have any changes in local git repository, commit or stash your current changes
  2. Create database.csv as central information of your VPN configuration

This step is required only FIRST TIME

make wg-meshconf-init
  1. Add nodes to your setup

This step is required each time you need to ADD A NEW NODE

Suggested setup:

  • Each node has its own subnet to not overlap and not screw up routing
  • In mesh-mode every node is pointing to it's public IP address
  • Wireguard integration in Flannel (Kubernetes CNI - network driver) will automatically create a second VPN with subnet per node and maintain it
make wg-meshconf-open
./vpn-add-peer.sh compute-1 --address 10.161.0.1/16 --endpoint COMPUTE-1-PUBLIC-IP
./vpn-add-peer.sh compute-2 --address 10.162.0.1/16 --endpoint COMPUTE-2-PUBLIC-IP
  1. Save your configuration

IF ANY NODE WAS ADDED, then you need to redeploy all changes

make wg-meshconf-commit
make wg-meshconf-deploy
  1. Check your VPN

Each node should ping each other e.g. 10.161.0.1 -> 10.162.0.1, login via SSH and perform pings. Check network interfaces, there should be new network interfaces with names e.g. compute-1, compute-2.

When you deploy K3s cluster there will be additional interfaces like flannel.1 created dynamically by Flannel inside Kubernetes cluster especially for Pods to be visible across machines.

You may want to read more about https://github.com/k4yt3x/wg-meshconf

Installing

  1. Create your own repository from this repository - use it as a template

  2. Install roles from Ansible Galaxy

ansible-galaxy install -r requirements.yml

  1. Prepare playbook.yaml, inventory/hosts.yaml - adjust variables to your needs

  2. Put credentials - passwords and ssh keys in inventory/group_vars/all.yaml

  3. Encrypt file inventory/group_vars/all.yaml using ansible-vault encrypt inventory/group_vars/all.yaml, so your passwords, ssh keys will stay secure while stored in GIT repository

  4. Install Kubernetes

7.1. Primary node at first

ansible-playbook ./playbook.yaml -k -i inventory/hosts.yaml --limit k3s-primary

7.2. Next on agent nodes (if any)

ansible-playbook ./playbook.yaml -k -i inventory/hosts.yaml --limit k3s-node

Upgrading

Following upgrade commands will only execute

Compute node

ansible-playbook ./playbook.yaml -k -i inventory/hosts.cfg -t cluster --limit k3s-node -e force_k3s_upgrade=true

Primary node

ansible-playbook ./playbook.yaml -k -i inventory/hosts.cfg -t k3s --limit k3s-primary -e force_k3s_upgrade=true

Updating services - e.g Traefik, Infracheck

When Ansible values are changed you may want to update the services, so there is a simplified procedure to update internal services.

Service tags:

  • git_argocd: Rewrite ArgoCD configuration in GIT
  • git_traefik: Rewrite Traefik configuration in GIT
  • git_infracheck: Rewrite Infracheck configuration in GIT
  • git_smtp: Rewrite SMTP configuration in GIT
  • git_telegraf: Rewrite Telegraf configuration in GIT
  • sealed_secrets: Reinstall Bitnami Sealed Secrets operator
  • argocd: Reinstall ArgoCD
  • git_all: Rewrite all applications that are written in GIT repository, push
# Tags explanation:
#  git_argocd: Produce ArgoCD configuration in GIT repository (to be replaced with other app e.g. git_traefik). Requires "git" tag.
#  git: Push changes to GIT repository
#  sync: Synchronize pushed changes immediately in ArgoCD

ansible-playbook ./playbook.yaml -i inventory/hosts.yaml --limit k3s-primary -t git_argocd,git,sync

Management commands

Primary

  • View logs: journalctl --unit k3s --follow
  • Start: systemctl start k3s
  • Stop: systemctl stop k3s
  • List nodes: k3s kubectl get nodes
  • Check node details: kubectl describe node ...

Using Sealed Secrets mechanism

After installing ArgoCD and synchronizing "sealed-secrets" application Ansible will store "sealed-secrets.cert.pem" file in artifacts local project directory. Use kubeseal cli locally using this secret, or on the server using certificate at path /etc/rancher/k3s/sealed-secrets.cert.pem.

# on primary node
cat configmap.yaml | kubeseal --cert /etc/rancher/k3s/sealed-secrets.cert.pem

# locally
cat configmap.yaml | kubeseal --cert ./artifacts/sealed-secrets.cert.pem

Disconnecting nodes

Procedure is to stop all pods, stop the agent, then delete the agent on primary.

# PART 1: On primary node
# stop or move all running pods on given machine
kubectl drain compute-xyz --ignore-daemonsets=true

# PART 2: On compute node
systemctl stop k3s-agent

# PART 3: On primary node - optionally, as this node will be anyway unschedulable 
# delete stopped agent from primary node list
kubectl delete node compute-xyz

Management model

To save resources Space Harbor is not providing any extra management services via HTTP, instead CLI tools are provided that requires cluster access.

ArgoCD is installed in Core variant without Web UI, RBAC, SSO. Use argocd admin dashboard --core while being at argocd namespace context, authenticated to the cluster to run fully-blown ArgoCD management panel in local WWW browser.

WARNING: Do not run argocd admin dashboard --core on your primary server, ArgoCD Core does not have authorization. Instead copy kube-config to your local computer and run this command on local computer with access to the cluster via Kubernetes HTTPS API server endpoint.