121 lines
5.2 KiB
Markdown
121 lines
5.2 KiB
Markdown
# Kubernetes Flavor Decision
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## Decision: k3s (confirmed)
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k3s is the best fit for Lab. OpenShift and most other flavors conflict with
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the puppet-managed, multi-arch, lightweight approach.
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## Evaluation
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| Flavor | Puppet-Friendly | ARM | Multi-arch | Enterprise | License | Verdict |
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|--------|:-:|:-:|:-:|:-:|---------|---------|
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| **k3s** | ✓ binary + config files | ✓ | ✓ | Rancher/SUSE | Apache 2.0 | **CHOSEN** |
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| **k0s** | ✓ single binary, config-driven | ✓ | ✓ | Mirantis | Apache 2.0 | Good alternative |
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| **kubeadm** | ✓ well-understood bootstrap | ✓ | ✓ | Upstream K8s | Apache 2.0 | Viable but heavier |
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| **RKE2** | ✓ config files | ✓ | ✓ | Rancher/SUSE | Apache 2.0 | Heavier k3s |
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| **OpenShift** | ✗ operator-driven, fights puppet | ✗ limited | ✗ limited | Red Hat | Proprietary | REJECTED |
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| **MicroK8s** | ⚠ snap-based, puppet+snaps awkward | ✓ | ✓ | Canonical | Apache 2.0 | Not great |
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| **Talos** | ✗ immutable OS, no SSH, no puppet | ✓ | ✓ | Sidero Labs | MPL 2.0 | Incompatible |
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## Why NOT OpenShift — Deep Analysis
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### OpenShift Does Overlap With Lab
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OpenShift is the closest existing thing to what Lab does. The overlap is real:
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| Capability | OpenShift | Lab |
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|-----------|-----------|-----|
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| Manages nodes end-to-end | Yes (RHCOS + MCO) | Yes (OpenVox + labels) |
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| Immutable infrastructure | Yes (rpm-ostree, operator-driven) | Yes (puppet convergence) |
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| Fights config drift | Yes (operators reconcile) | Yes (puppet + sync pillar) |
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| Built-in monitoring | Yes (Prometheus + Alertmanager bundled) | Yes (health aggregator) |
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| Built-in secrets | Yes (etcd-encrypted secrets) | Yes (secret store + local cache) |
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| Certificate management | Yes (internal CA, auto-rotation) | Yes (identity layer) |
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| Node lifecycle | Yes (MachineSet, MachinePools) | Yes (onboard, labels, providers) |
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| Self-managing | Yes (operators update themselves) | Yes (lab manages itself) |
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### Why OpenShift Still Doesn't Fit
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**1. Single OS** — OpenShift control plane = RHCOS only. Can't run on Apple Silicon,
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Asahi Linux, or any non-RHCOS system. Lab needs Ubuntu, Debian, Fedora, AlmaLinux,
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XCP-ng, VyOS across x86 and ARM.
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**2. K8s only** — OpenShift manages k8s nodes. Lab manages everything: k8s nodes,
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standalone VMs, bare metal hypervisors, network appliances, physical servers that
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will never run k8s. Not everything is a container.
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**3. Single cluster scope** — OpenShift manages one cluster. Lab manages homelab k3s +
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enterprise AWS EKS + XCP-ng hypervisors + bare metal + OVH vRack. Cross-provider,
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cross-cluster.
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**4. Fights puppet** — OpenShift has ~30+ operators that each own a piece of the system.
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If puppet changes kubelet config, the Machine Config Operator detects "drift" and
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reverts it. Two reconciliation loops fighting each other, possibly rebooting nodes
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in a loop. You're supposed to change everything via CRDs, not external tools.
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**5. No XCP-ng/hypervisor management** — Can't provision VMs on XCP-ng, manage Xen
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hosts, or understand hypervisors that aren't VMware/OpenStack.
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**6. Throws away puppet modules** — Company has existing puppet modules. OpenShift's
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model is operators, not puppet. Complete rewrite of config management.
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**7. Heavyweight** — Minimum 6 nodes, 88GB RAM just for the platform. k3s uses 512MB.
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Our entire homelab is 5 nodes, 320GB RAM.
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**8. ARM limited** — RHCOS on Apple Silicon doesn't exist. ARM support is limited to
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AWS Graviton and some server ARM platforms.
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### The Scope Difference
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```
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OpenShift: "I am your platform. Everything runs in me. I control the OS."
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Scope: Kubernetes cluster + its nodes
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Lab: "I manage your infrastructure. K8s is one thing I deploy."
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Scope: Everything — VMs, bare metal, hypervisors, k8s,
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network gear, containers, across any provider
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```
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Lab is closer to what OpenShift + Satellite + RHCOS + ACM (Advanced Cluster Management)
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do **together** — but unified, lighter, open source, and not locked to Red Hat's ecosystem.
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## Why k3s
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- **Puppet-friendly** — it's just a binary and config files in `/etc/rancher/k3s/`
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- **Ultra-light** — runs on Mac Studio, ARM boxes, small VMs
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- **Multi-arch** — native x86 and ARM
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- **Same K8s API** as EKS/GKE — portable to cloud
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- **Single binary** — trivial to manage with puppet
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- **Proven** — CNCF certified, widely used in edge/IoT/homelab
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## k3s via Puppet (OpenVox)
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```puppet
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# Label: k8s-server → puppet class
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class kubernetes::server {
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class { 'k3s::server':
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token => lab::secret('k8s/cluster-token'),
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cluster_init => true,
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tls_san => [$facts['fqdn'], 'k8s.lab.internal'],
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}
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}
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# Label: k8s-worker → puppet class
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class kubernetes::worker {
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class { 'k3s::worker':
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server_url => 'https://k8s.lab.internal:6443',
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token => lab::secret('k8s/cluster-token'),
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}
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}
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```
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Same puppet classes work on bare metal, XCP-ng VM, EC2 instance, any architecture.
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## k0s as Backup Option
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If k3s ever becomes problematic, k0s is the closest alternative:
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- Also single binary, config-driven, multi-arch
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- `k0sctl` adds cluster management (bootstrap, upgrade, reset)
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- Mirantis backing (Lens, Docker EE)
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- Worth monitoring but no reason to switch from k3s today
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