Harvester Analysis

Overview

Harvester is a Hyperconverged Infrastructure (HCI) platform built on Kubernetes, designed to provide VM and container management on a unified platform. It combines compute, storage, and networking with built-in K3s for orchestration.

Key Facts:

• Latest Version: Harvester 1.4 (based on K3s 1.30+)
• Foundation: Built on RancherOS 2.0, K3s, and KubeVirt
• Support: Supported by SUSE (acquired Rancher)
• Architecture: HCI platform with VM + container workloads
• Management: Web UI + kubectl + Rancher integration

Kubernetes Installation Methods

Harvester includes K3s as its foundation - Kubernetes is built-in.

Built-in K3s (Only Option)

Installation Process:

1. Boot Harvester ISO (interactive installer or PXE)
2. Complete installation wizard (web UI or console)
3. Create cluster (automatic K3s deployment)
4. Access via web UI or kubectl

Interactive Installation:

# Boot from Harvester ISO
1. Choose "Create a new Harvester cluster"
2. Configure:
   - Cluster token
   - Node role (management/worker/witness)
   - Network interface (management network)
   - VIP (Virtual IP for cluster access)
   - Storage disk (Longhorn persistent storage)
3. Install completes (15-20 minutes)
4. Access web UI at https://<VIP>

Configuration (cloud-init for automated install):

# config.yaml
token: my-cluster-token
os:
  hostname: harvester-node-1
  modules:
    - kvm
  kernel_parameters:
    - intel_iommu=on
install:
  mode: create
  device: /dev/sda
  iso_url: https://releases.rancher.com/harvester/v1.4.0/harvester-v1.4.0-amd64.iso
  vip: 192.168.1.100
  vip_mode: static
  networks:
    harvester-mgmt:
      interfaces:
        - name: eth0
      default_route: true
      ip: 192.168.1.10
      subnet_mask: 255.255.255.0
      gateway: 192.168.1.1

Pros:

• Complete HCI solution (VMs + containers)
• Web UI for management (no CLI required)
• Built-in storage (Longhorn CSI)
• Built-in networking (multus, SR-IOV)
• VM live migration
• Rancher integration for multi-cluster management
• K3s built-in (no separate Kubernetes install)

Cons:

• Heavy resource requirements (8GB+ RAM per node)
• Complex architecture (steep learning curve)
• Larger attack surface than minimal OS
• Overkill for container-only workloads
• Requires 3+ nodes for production HA

Cluster Initialization Sequence

sequenceDiagram
    participant Admin
    participant Server as Bare Metal Server
    participant Harvester as Harvester HCI
    participant K3s as K3s / KubeVirt
    participant Storage as Longhorn Storage
    
    Admin->>Server: Boot Harvester ISO
    Server->>Harvester: Start installation wizard
    Harvester-->>Admin: Interactive console/web UI
    Admin->>Harvester: Configure cluster (token, VIP, storage)
    Harvester->>Server: Partition disks (OS + Longhorn storage)
    Harvester->>Server: Install RancherOS 2.0 base
    Harvester->>Server: Install K3s components
    Server->>Server: Reboot
    Harvester->>K3s: Start K3s server
    K3s->>Server: Initialize control plane
    K3s->>Server: Deploy Harvester operators
    K3s->>Storage: Deploy Longhorn for persistent storage
    K3s->>Server: Deploy KubeVirt for VM management
    K3s->>Server: Deploy multus CNI (multi-network)
    Harvester-->>Admin: Web UI ready at https://<VIP>
    Admin->>Harvester: Add additional nodes (join cluster)
    Harvester->>K3s: Join nodes to cluster
    K3s->>Storage: Replicate storage across nodes
    Harvester-->>Admin: Cluster ready (20-30 minutes)
    Admin->>Harvester: Create VMs or deploy containers

Maintenance Requirements

OS Updates

Harvester Upgrades (includes OS + K3s):

# Via Web UI:
# Settings → Upgrade → Select version → Start upgrade

# Via kubectl (after downloading upgrade image):
kubectl apply -f https://releases.rancher.com/harvester/v1.4.0/version.yaml

# Monitor upgrade progress
kubectl get upgrades -n harvester-system

Frequency:

• Harvester releases: Every 2-3 months (minor versions)
• Security patches: Included in Harvester releases
• K3s upgrades: Bundled with Harvester upgrades
• No separate OS patching (managed by Harvester)

Kubernetes Upgrades

K3s is upgraded with Harvester - no separate upgrade process.

Version Compatibility:

• Harvester 1.4.x → K3s 1.30+
• Harvester 1.3.x → K3s 1.28+
• Harvester 1.2.x → K3s 1.26+

Upgrade Process:

1. Web UI or kubectl to trigger upgrade
2. Rolling upgrade of nodes (one at a time)
3. VM live migration during node upgrades
4. Automatic rollback on failure

Resource Overhead

Single Node (Harvester HCI):

• RAM: 8GB minimum (16GB recommended for VMs)
• CPU: 4 cores minimum (8 cores recommended)
• Disk: 250GB minimum (SSD recommended)
  • 100GB for OS/Harvester components
  • 150GB+ for Longhorn storage (VM disks)
• Network: 1 Gbps minimum (10 Gbps for production)

Three-Node Cluster (Production HA):

• RAM: 32GB per node (64GB for VM-heavy workloads)
• CPU: 8 cores per node minimum
• Disk: 500GB+ per node (NVMe SSD recommended)
• Network: 10 Gbps recommended (separate storage network ideal)

Comparison:

• Ubuntu + k3s: 1GB RAM
• Talos: 768MB RAM
• Harvester: 8GB+ RAM (much heavier)

Note: Harvester is designed for multi-node HCI, not single-node homelabs.

Security Posture

Strengths:

• SELinux-based (RancherOS 2.0 foundation)
• Immutable OS layer (similar to Talos)
• RBAC built-in (Kubernetes + Rancher)
• Network segmentation (multus CNI)
• VM isolation (KubeVirt)
• Signed images and secure boot support

Attack Surface:

• Larger than Talos/k3s: Includes web UI, VM management, storage layer
• KubeVirt adds additional components
• Web UI is additional attack vector
• More processes than minimal OS (~50+ services)

Security Features:

# VM network isolation example
apiVersion: network.harvesterhci.io/v1beta1
kind: VlanConfig
metadata:
  name: production-vlan
spec:
  vlanID: 100
  uplink:
    linkAttributes: 1500

Hardening:

• Firewall rules (web UI or kubectl)
• RBAC policies (restrict VM/namespace access)
• Network policies (isolate workloads)
• Rancher authentication integration (LDAP, SAML)

Learning Curve

Ease of Adoption: ⭐⭐⭐ (Moderate)

• Web UI simplifies management (no CLI required for basic tasks)
• Requires understanding of VMs + containers
• Kubernetes knowledge helpful but not required initially
• Longhorn storage concepts (replicas, snapshots)
• KubeVirt for VM management (learning curve)

Required Knowledge:

• Basic Kubernetes concepts (pods, services)
• VM management (KubeVirt/libvirt)
• Storage concepts (Longhorn, CSI)
• Networking (VLANs, SR-IOV optional)
• Web UI navigation

Debugging:

# Access via kubectl (kubeconfig from web UI)
kubectl get nodes -n harvester-system

# View Harvester logs
kubectl logs -n harvester-system <pod-name>

# VM console access (via web UI or virtctl)
virtctl console <vm-name>

# Storage debugging
kubectl get volumes -A

Community Support

Ecosystem Maturity: ⭐⭐⭐⭐ (Good)

• Documentation: Excellent official docs
• Community: Active Slack, GitHub Discussions, forums
• Commercial Support: Available from SUSE/Rancher
• Third-Party Tools: Rancher ecosystem integration
• Tutorials: Growing number of guides and videos

Resources:

• Harvester Documentation
• Harvester GitHub
• Rancher Community Slack
• SUSE Support

Pros and Cons Summary

Pros

• Good, because unified platform for VMs + containers (no separate hypervisor)
• Good, because built-in K3s (Kubernetes included)
• Good, because web UI simplifies management (no CLI required)
• Good, because built-in persistent storage (Longhorn CSI)
• Good, because VM live migration (no downtime during maintenance)
• Good, because multi-network support (multus CNI, SR-IOV)
• Good, because Rancher integration (multi-cluster management)
• Good, because automatic upgrades (OS + K3s + components)
• Good, because commercial support available (SUSE)
• Good, because designed for bare-metal HCI (no cloud dependencies)
• Neutral, because immutable OS layer (similar to Talos benefits)

Cons

• Bad, because very heavy resource requirements (8GB+ RAM minimum)
• Bad, because complex architecture (KubeVirt, Longhorn, multus, etc.)
• Bad, because overkill for container-only workloads (use k3s/Talos instead)
• Bad, because larger attack surface than minimal OS (web UI, VM layer)
• Bad, because requires 3+ nodes for production HA (not single-node friendly)
• Bad, because steep learning curve for full feature set (VMs + storage + networking)
• Bad, because relatively new platform (less mature than Ubuntu/Fedora)
• Bad, because limited to Rancher ecosystem (vendor lock-in)
• Bad, because slower to adopt latest Kubernetes versions (depends on K3s bundle)
• Neutral, because opinionated HCI design (pro for VM use cases, con for simplicity)

Recommendations

Best for:

• Hybrid workloads (VMs + containers on same platform)
• Homelab users wanting to consolidate VM hypervisor + Kubernetes
• Teams familiar with Rancher ecosystem
• Multi-node clusters (3+ nodes)
• Environments requiring VM live migration
• Users wanting web UI for infrastructure management
• Replacing VMware/Proxmox + Kubernetes with unified platform

Best Installation Method:

• Only option: Interactive ISO install or PXE with cloud-init

Avoid if:

• Running container-only workloads (use k3s or Talos instead)
• Limited resources (< 8GB RAM per node)
• Single-node homelab (Harvester designed for multi-node)
• Want minimal attack surface (use Talos)
• Prefer traditional Linux shell access (use Ubuntu/Fedora)
• Need latest Kubernetes versions immediately (Harvester lags upstream)

Comparison with Other Options

Verdict: Harvester is excellent for VM + container hybrid workloads with 3+ nodes, but overkill for container-only infrastructure. Use Talos or k3s for Kubernetes-only clusters, Ubuntu/Fedora for general-purpose servers.

Advanced Features

VM Management (KubeVirt)

Create VMs via YAML:

apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  name: ubuntu-vm
spec:
  running: true
  template:
    spec:
      domain:
        devices:
          disks:
            - name: root
              disk:
                bus: virtio
        resources:
          requests:
            memory: 4Gi
            cpu: 2
      volumes:
        - name: root
          containerDisk:
            image: docker.io/harvester/ubuntu:22.04

Live Migration

Move VMs between nodes:

# Via web UI: VM → Actions → Migrate

# Via kubectl
kubectl patch vm ubuntu-vm --type merge -p '{"spec":{"running":false}}'
kubectl patch vm ubuntu-vm --type merge -p '{"spec":{"running":true}}'

Backup and Restore

Harvester supports VM backups:

# Configure S3 backup target (web UI)
# Create VM snapshot
# Restore from snapshot or backup

Rancher Integration

Manage multiple clusters:

# Import Harvester cluster into Rancher
# Deploy workloads across clusters
# Central authentication and RBAC

Use Case Examples

Use Case 1: Replace VMware + Kubernetes

Scenario: Currently running VMware ESXi for VMs + separate Kubernetes cluster

Harvester Solution:

• Consolidate to 3-node Harvester cluster
• Migrate VMs to KubeVirt
• Deploy containers on same cluster
• Save VMware licensing costs

Benefits:

• Single platform for VMs + containers
• Unified management (web UI + kubectl)
• Built-in HA and live migration

Use Case 2: Homelab with Mixed Workloads

Scenario: Need Windows VMs + Linux containers + storage server

Harvester Solution:

• Windows VMs via KubeVirt (GPU passthrough supported)
• Linux containers via K3s workloads
• Longhorn for persistent storage (NFS export supported)

Benefits:

• No need for separate Proxmox/ESXi
• Kubernetes-native management
• Learn enterprise HCI platform

Use Case 3: Edge Computing

Scenario: Deploy compute at remote sites (3-5 nodes each)

Harvester Solution:

• Harvester cluster at each edge location
• Rancher for central management
• VM + container workloads

Benefits:

• Autonomous operation (no cloud dependency)
• Rancher multi-cluster management
• Built-in storage and networking

Production Readiness

Production Use: ✅ Yes (used in enterprise environments)

High Availability:

• 3+ nodes required for HA
• Witness node for even-node clusters
• VM live migration during maintenance
• Longhorn 3-replica storage

Monitoring:

• Built-in Prometheus + Grafana
• Rancher monitoring integration
• Alerting and notifications

Disaster Recovery:

• VM backups to S3
• Cluster backups (etcd + config)
• Restore to new cluster

Enterprise Features:

• Rancher authentication (LDAP, SAML, OAuth)
• Multi-tenancy (namespaces, RBAC)
• Audit logging
• Network policies