# Kh Assistant

> Use when users need help with kube-hetzner configuration, debugging, or questions - acts as an intelligent assistant with live repo access

- Skill: `mysticaltech/kh-assistant` (Agent Skill)
- Install (CLI): `npx skillmds@latest add mysticaltech/kh-assistant`
- Raw SKILL.md: https://api.skillmd.com/api/skills/mysticaltech/kh-assistant/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: mysticaltech (https://skillmd.com/u/mysticaltech)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/mysticaltech/kh-assistant

---


# KH Assistant

Expert assistant for **terraform-hcloud-kube-hetzner** — deploying production-ready k3s/RKE2 clusters on Hetzner Cloud.

## Startup Checklist

**ALWAYS do these first before answering any question:**

```bash
# 1. Get latest release version
gh release list --repo kube-hetzner/terraform-hcloud-kube-hetzner --limit 1 --json tagName,publishedAt

# 2. Read key files for context; use exact search to scope large files
# - variables.tf — all configurable options
# - docs/llms.md — PRIMARY comprehensive documentation (~60k tokens)
# - kube.tf.example — working example
# - CHANGELOG.md — recent changes
```

**For Hetzner-specific info** (server types, pricing, locations):
```bash
# Use web search
WebSearch "hetzner cloud server types pricing 2026"
```

---

## Route to Sibling Skills First

**Do not hand-solve a specialized workflow inline when a sibling skill matches.**
Recommend the skill, explain why it fits, and invoke it when available. End users
should mainly be routed to `migrate-v2-to-v3`, `upgrade-cluster`, and
`debug-node`; maintainer-only skills are for repository operations, not normal
cluster support.

| User intent | Skill | What it does | Invocation |
|-------------|-------|--------------|------------|
| Migrate an existing Terraform root or cluster from module v2.x to v3.x | `migrate-v2-to-v3` | Audits and rewrites the v2 contract, preserves state, and enforces the protected-infrastructure plan gate | `/migrate-v2-to-v3` |
| Upgrade or harden a live cluster, module/providers, k3s/RKE2, or replace nodes safely | `upgrade-cluster` | Separates module convergence from runtime rollout and proves Terraform plus Kubernetes health | `/upgrade-cluster` |
| Diagnose an unreachable node, SSH/cloud-init failure, or stuck provisioning | `debug-node` | Uses Hetzner rescue mode to mount and inspect the node without working node SSH | `/debug-node` |
| Validate module changes with Terraform and OpenTofu | `test-changes` | Runs formatting, validation, compatibility, example, and plan gates against a supplied test root | `/test-changes` |
| Implement a GitHub issue (**maintainer only**) | `fix-issue` | Fetches and verifies the issue, implements the root-cause fix, tests it, and preserves contributor credit | `/fix-issue <number>` |
| Classify and respond to a GitHub issue (**maintainer only**) | `triage-issue` | Checks evidence and duplicates, classifies the report, and drafts the appropriate response/action | `/triage-issue <number>` |
| Review a pull request (**maintainer only**) | `review-pr` | Performs a security, compatibility, regression, and code-quality review of an untrusted contribution | `/review-pr <number>` |
| Synchronize project documentation (**maintainer only**) | `sync-docs` | Keeps `variables.tf`, generated/reference docs, examples, migration docs, and skills coherent | `/sync-docs` |
| Prepare or execute a release (**maintainer only**) | `prepare-release` | Verifies release content and versions; tags/pushes only with explicit maintainer release authority | `/prepare-release` |
| Prove risky changes across the live v3 matrix (**maintainer only**) | `running-stabilization-loop` | Iteratively runs, diagnoses, fixes, and reruns the k3s/RKE2 matrix plus tagged-version upgrade paths | `/running-stabilization-loop` |

If the matching skill is not installed, tell the user to install from the
project repository and then invoke it:

```bash
# Interactive selection
npx skills add kube-hetzner/terraform-hcloud-kube-hetzner

# Install only the recommended skill (example)
npx skills add kube-hetzner/terraform-hcloud-kube-hetzner --skill migrate-v2-to-v3

# Install globally for supported agents
npx skills add kube-hetzner/terraform-hcloud-kube-hetzner -g
```

Do not recommend maintainer-only skills to end users unless they are explicitly
contributing to or maintaining this repository.

---

## Knowledge Sources

### Primary Documentation Files

| File | Purpose | When to Use |
|------|---------|-------------|
| `docs/llms.md` | **PRIMARY** - Comprehensive variable reference | First stop for any variable question |
| `variables.tf` | Variable definitions with types/defaults | Verify exact syntax and defaults |
| `locals.tf` | Core logic and computed values | Understanding how features work |
| `kube.tf.example` | Complete working example | Template for configurations |
| `CHANGELOG.md` | Version history, breaking changes | Upgrade questions, "when was X added" |
| `MIGRATION.md` | Canonical old-to-new migration variable map | v2 -> v3 upgrade questions |
| `docs/v2-to-v3-migration.md` | v2 -> v3 operator playbook | Existing-cluster major upgrades |
| `docs/v3-release-evidence.md` | Live v3 proof, CI caveats, RKE2 sizing evidence | Release readiness, "is this proven?" questions |
| `docs/v3-topology-recommendations.md` | v3 topology chooser and "what not to choose" rules | New designs, multinetwork, Gateway API, registry mirror |
| `docs/selinux.md` | SELinux policy provenance and AVC workflow | Workload denials, policy proposals, disable-vs-fix decisions |
| `README.md` | Project overview, quick start | New user orientation |

### Specialized Documentation

| File | Topic |
|------|-------|
| `docs/terraform.md` | Auto-generated terraform docs |
| `docs/ssh.md` | SSH configuration, key formats |
| `docs/add-robot-server.md` | Hetzner dedicated server integration |
| `docs/private-network-egress.md` | NAT router setup for private clusters |
| `docs/customize-mount-path-longhorn.md` | Longhorn storage customization |

### GitHub (Live Data)

```bash
# Latest release
gh release list --repo kube-hetzner/terraform-hcloud-kube-hetzner --limit 1

# Search issues for errors
gh issue list --repo kube-hetzner/terraform-hcloud-kube-hetzner --search "<error>" --state all

# Search discussions for how-to
gh api repos/kube-hetzner/terraform-hcloud-kube-hetzner/discussions --jq '.[].title'

# Check if variable exists
grep 'variable "<name>"' variables.tf
```

### Current v3 Baseline

Verify the live tag at startup; the checked-in release baseline is **v3.2.1**.

| Fact | Current contract |
|------|------------------|
| Kubernetes distribution | k3s is the default; RKE2 is supported via `kubernetes_distribution = "rke2"` |
| Kubernetes version policy | k3s defaults to the upstream `stable` channel; pin a version/channel when reproducibility or v2 minor preservation matters |
| Node OS | Brand-new nodepools default to Leap Micro; existing MicroOS nodepools remain supported and are preserved on normal v2 upgrades |
| Addon versions | Unset addon version inputs use the reviewed deterministic module matrix; `latest` is an explicit opt-in to floating upstream behavior |

---

## Critical Rules

### MUST Follow — Never Violate

| Rule | Explanation |
|------|-------------|
| **At least 1 control plane** | `control_plane_nodepools` must have at least one entry with `count >= 1` |
| **Supported OS only** | New nodes default to Leap Micro; MicroOS is legacy/upgrade support. Never suggest Ubuntu, Debian, or other generic OS images. |
| **Network region coverage** | `network_region` must contain ALL node locations |
| **Odd control plane counts for HA** | Use 1, 3, or 5 — never 2 or 4 (quorum requirement) |
| **Autoscaler is separate** | `autoscaler_nodepools` is independent from `agent_nodepools` |
| **Latest version always** | Always fetch and use the latest release tag |

### Common Mistakes to Prevent

| Mistake | Correct |
|---------|---------|
| Empty control_plane_nodepools | At least one with count >= 1 |
| 2 control planes for "HA" | Use 3 (odd number for quorum) |
| Suggesting Ubuntu/Debian | Use Leap Micro by default; MicroOS only for legacy/explicit nodepools |
| Location not in network_region | network_region must cover all locations |
| Confusing autoscaler with agents | Autoscaler pools are completely separate |
| Using old version | Always check latest release first |
| Using v2 input names in v3 | Rewrite with `MIGRATION.md`: `enable_*` booleans, `kubernetes_distribution`, `k3s_channel`, `rke2_channel`, `node_transport_mode`, and `network_subnet_mode` |
| Raw Hetzner private multinetwork for >100 nodes | Use `node_transport_mode = "tailscale"` or the experimental Cilium public overlay; Hetzner private Networks do not route to each other |
| Treating external Tailscale hooks as node transport | Use `node_transport_mode = "tailscale"` for cluster transport; use `node_connection_overrides` only for user-owned operator access |
| Treating Cloudflare Mesh/WARP as supported node transport | Use Tailscale for kube-hetzner-managed secure node transport; Cloudflare Access/Tunnel is external operator/app access only |
| Assuming one Hetzner Network can exceed 100 nodes | Shard across multiple Hetzner Networks and count all attachments, including control planes, static agents, autoscaler `max_nodes`, NAT routers, and load balancers |
| Promising static 10k placement spread in one project | Hetzner spread groups are 10 servers each and 50 groups per project; use autoscaler/network shards or split across projects/clusters |
| Confusing Cilium Gateway API with Traefik Gateway provider | Use `cilium_gateway_api_enabled` for Cilium, `traefik_provider_kubernetes_gateway_enabled` for Traefik |
| Enabling Cilium Gateway API with kube-proxy | Requires `cni_plugin = "cilium"` and `enable_kube_proxy = false` |
| Enabling embedded registry mirror on low-trust nodes | Use only for equal-trust clusters; warn about credential sharing and tag poisoning |
| Disabling SELinux globally for one workload denial | Follow `docs/selinux.md`: collect AVCs, try udica, use per-pool `selinux = false` only as the last resort |
| Assuming RKE2 needs 8GB control planes | v3 size-aware kubelet reservations make 4GB `cx23` control planes viable; still size production for workload headroom |
| Manual cloud deletes during teardown | Use `scripts/destroy.sh` first; `scripts/cleanup.sh` is the forceful fallback and targets the token's entire HCloud project |

### v3 Topology Shortcuts

| Need | Recommendation |
|------|----------------|
| Small dev | Single control plane, one small agent pool, no ingress unless needed |
| Normal HA | 3 control planes, 2+ agents, one primary Hetzner Network |
| Private-only | NAT router and private control-plane LB on the primary Network |
| Secure API/SSH | `node_transport_mode = "tailscale"` and close public API/SSH firewall sources |
| Cloudflare-protected operator/app access | User-managed Cloudflare Access/Tunnel in front of kube API, SSH, Rancher, Grafana, or ingress; keep node transport as Hetzner private or Tailscale |
| +100 Cloud nodes | Tailscale node transport plus one external Hetzner Network shard per 100-node budget |
| 10k reference | Autoscaler-first Tailscale multinetwork; point to `examples/tailscale-node-transport/massive-10000-nodes.tf.example` |
| Cilium Gateway API | Cilium, `enable_kube_proxy = false`, `cilium_gateway_api_enabled = true` |
| Heavy image pulls | `embedded_registry_mirror.enabled = true` only on trusted clusters |

---

## Common Issues Catalog

### v3.0.0 Regressions Fixed in v3.0.1

- **Zero-agent post-apply plan failure (#2236, #2238):** v3.0.0 clusters
  with `agent_nodepools = []` failed later plans with
  `no change found for terraform_data.agents`. Upgrade to v3.0.1 or later; it routes
  readiness triggers through a single agent-id aggregator, without replacing
  or rerunning post-install readiness during the upgrade.
- **Static agents assigned to the wrong subnet (#2239):** v3.0.0 assigned
  primary-network static agents from the control-plane subnet. v3.0.1 or later restores
  per-nodepool addressing. Clusters first created on v3.0.0 require the release
  note's rolling agent migration: cordon/drain one agent, target-apply that
  agent's in-place private-NIC detach/reattach and k3s/RKE2 config restart,
  verify it is `Ready` on the intended subnet, uncordon it, and continue. If
  interface mapping does not recover, reboot so `kh-rename-interface.service`
  can verify it. Normal clusters upgraded from v2.x retain the v2 IP formula
  and are unaffected.

### Known Error Patterns

| Error | Cause | Solution |
|-------|-------|----------|
| `cannot sum empty list` | control_plane_nodepools is empty or all counts are 0 | Add at least one control plane with count >= 1 |
| `NAT router primary IPs will be replaced` | Pre-v2.19.0 used deprecated 'datacenter' attribute | Allow recreation (IPs change) or do state migration |
| `Traefik returns 404 for all routes` | Traefik v34+ config change | Upgrade to module v2.19.0+ |
| `SSH connection refused or timeout` | Key format, firewall, or node not ready | Check ssh_public_key format, verify firewall_ssh_source |
| `Node stuck in NotReady` | Network region mismatch or token issues | Ensure network_region contains all node locations |
| `Error creating network subnet` | Subnet CIDR conflicts | Check network_ipv4_cidr doesn't overlap with existing |
| `cloud-init failed` | Leap Micro/MicroOS snapshot missing, wrong region, wrong architecture, or wrong distro label | Recreate snapshots with packer in the correct region/architecture and k3s/RKE2 SELinux variant |
| `resource_already_detaching` or LB network 422 during destroy | Known benign ingress-LB detach race between CCM and Terraform ownership | Run `scripts/destroy.sh`; it retries only this race and then prints an orphan report |
| Network/subnet destroy hangs with autoscaler enabled | Autoscaler-created servers are not in Terraform state and still pin the network | Wait until the control plane is dead, or scale autoscaler `min_nodes = 0`, then delete the orphan |
| SELinux `avc: denied` workload failures | Missing workload policy, not automatically a module bug | Follow `docs/selinux.md`; collect AVC evidence and try udica before upstreaming policy or disabling a pool |

### Debugging Workflow

```
1. Check Common Issues table above
2. Search GitHub issues: gh issue list --search "<error>" --state all
3. Search docs/llms.md for related variables
4. Check locals.tf for the logic
5. Provide: Root cause → Fix → Prevention
6. Link to relevant GitHub issues if found
```

---

## Hetzner Cloud Context

### Server Types (x86)

| Type | vCPU | RAM | Disk | Best For |
|------|------|-----|------|----------|
| `cx23` | 2 | 4GB | 40GB | Minimal dev, small k3s/RKE2 control planes |
| `cx33` | 4 | 8GB | 80GB | Production control plane, moderate workers |
| `cx43` | 8 | 16GB | 160GB | Production workers |
| `cx53` | 16 | 32GB | 320GB | Heavy workloads |

`cx23` is the current minimum used throughout the v3 examples. The RKE2 + Leap
Micro `cx23` control-plane shape is live-proven in `docs/v3-release-evidence.md`
after size-aware kubelet reservations landed.

### Server Types (ARM — CAX, cost-optimized)

| Type | vCPU | RAM | Disk | Best For |
|------|------|-----|------|----------|
| `cax11` | 2 | 4GB | 40GB | ARM dev |
| `cax21` | 4 | 8GB | 80GB | ARM workloads |
| `cax31` | 8 | 16GB | 160GB | ARM production |
| `cax41` | 16 | 32GB | 320GB | ARM heavy |

### Locations

| Region | Locations | Network Zone |
|--------|-----------|--------------|
| Germany | `fsn1`, `nbg1` | `eu-central` |
| Finland | `hel1` | `eu-central` |
| USA East | `ash` | `us-east` |
| USA West | `hil` | `us-west` |
| Singapore | `sin` | `ap-southeast` |

**Rule**: All locations must be in the same `network_region`.

---

## Configuration Workflows

### Workflow: Creating kube.tf

```
1. FIRST: Get latest release
   gh release list --repo kube-hetzner/terraform-hcloud-kube-hetzner --limit 1

2. Ask clarifying questions:
   - Use case: Production / Development / Testing?
   - Kubernetes distribution: k3s (default) / RKE2?
   - HA: Single node / 3 control planes / Super-HA (multi-location)?
   - Budget: Which server types?
   - Network: Public / Private with NAT router?
   - CNI: Flannel (default) / Cilium / Calico?
   - Storage: Longhorn needed?
   - Ingress: Traefik (default) / Nginx / HAProxy?

3. Query variables.tf and docs/llms.md for relevant options

4. Generate complete config with:
   - Module source and version (latest!)
   - Required: hcloud_token, SSH keys, `kubernetes_distribution` only when not default k3s
   - Requested features
   - Helpful comments

5. Validate syntax:
   terraform fmt -recursive
   terraform validate
```

### Workflow: Debugging

```
1. Parse the error:
   - Terraform error vs k3s error vs provider error
   - Which resource?
   - What operation?

2. Check Common Issues Catalog (above)

3. Search GitHub:
   gh issue list --search "<error keyword>" --state all

4. Read relevant code:
   - locals.tf for logic
   - variables.tf for options
   - Specific .tf files based on error

5. Provide solution:
   - Root cause explanation
   - Fix (config change or upgrade)
   - Prevention steps
   - Link to related issues
```

For K3s certificate expiry, remind the operator that the admin kubeconfig also
contains client certificates. After restarting or rotating control-plane
certificates, retrieve a fresh `/etc/rancher/k3s/k3s.yaml` over SSH from a
healthy control-plane node, save it with mode `0600`, and replace its
`https://127.0.0.1:6443` server with the cluster's reachable API endpoint before
testing it with `kubectl`. Do not tell operators to keep using a stale local
kubeconfig after certificate recovery.

### Workflow: Teardown / Destroy

```
1. Run from the user's Terraform root:
   <module-checkout>/scripts/destroy.sh -auto-approve
2. Let the wrapper detect the initialized Terraform/OpenTofu engine. It retries
   only recognized benign LB-detach/network-in-use convergence races, then
   always prints a read-only hcloud orphan report when credentials and the
   cluster name are available.
3. If autoscaler-created servers pin network/subnet deletion, either set every
   autoscaler pool `min_nodes = 0` and apply before destroy, or wait until the
   control plane is dead. Then use the orphan report to identify and delete only
   the autoscaler-created servers, and rerun `scripts/destroy.sh`.
4. Use <module-checkout>/scripts/cleanup.sh only when state is already broken or
   the read-only report identifies leftovers. It treats the token's entire
   HCloud project as cluster-dedicated, so review its dry run before deletion
   and include persistent data only deliberately.
```

### Workflow: Feature Questions

```
1. Check docs/llms.md FIRST (primary reference)
2. Verify in variables.tf (exact syntax)
3. Check kube.tf.example for usage
4. Search GitHub discussions for examples
5. Provide answer with file references
```

### Workflow: Upgrades

```
1. Get current and target versions
2. If this is v2.x -> v3.x, use the /migrate-v2-to-v3 skill workflow
3. Read CHANGELOG.md, MIGRATION.md, and docs/v2-to-v3-migration.md
4. Check for:
   - Removed/renamed variables
   - Changed defaults
   - Required migrations
   - Inverted boolean semantics
   - State migration requirements
   - Network/subnet/LB/server replacement risk
   - Production no-destroy gate from `MIGRATION.md`
5. Generate upgrade steps:
   - Update version in kube.tf
   - terraform init -upgrade
   - terraform validate
   - terraform plan -out=<planfile> (check for destructions!)
   - terraform show -json <planfile> and run the protected hcloud no-destroy gate from `MIGRATION.md`
   - terraform apply
6. Warn if terraform plan shows resource recreation
```

### Workflow: v2 -> v3 Migrations

Use `.claude/skills/migrate-v2-to-v3/SKILL.md` for the exact workflow.

Core rules:
- Back up state before editing.
- Rewrite v2-only inputs using `MIGRATION.md`.
- Invert positive/negative booleans carefully.
- Preserve the first-apply compatibility freeze unless the operator deliberately
  chooses a topology/runtime change: `k3s_channel = "stable"` is the v3 default,
  but v2 upgrades usually pin `k3s_channel = "v1.33"` or `k3s_version`; unset
  addon versions become deterministic reviewed defaults; `network_subnet_mode`
  stays `per_nodepool`; `node_transport_mode` stays `hetzner_private`.
- Remove `network_id = 0`; omitted/null means the primary Network in v3.
- Remove control-plane `network_id`; control planes stay on the primary Network.
- For secure Tailnet access or private multinetwork scale, prefer `node_transport_mode = "tailscale"`. For v2-to-v3 upgrades, introduce large multinetwork scale in a separate audited plan after the base upgrade. Tailscale mode keeps Kubernetes node IPs on Hetzner private addresses and can advertise node-private `/32` routes with Tailscale subnet-route SNAT disabled. Active agent/autoscaler nodepools in Tailscale mode must set `network_scope = "primary"` or `network_scope = "external"` so invalid same-root external Network configs fail at plan time.
- Do not suggest Calico with Tailscale node transport yet. Flannel is first supported; Cilium is still explicitly experimental in this transport mode.
- For Cloudflare, recommend only the external Access/Tunnel pattern for kube API, SSH, Rancher, Grafana, or ingress. Do not suggest Cloudflare Mesh/WARP as kube-hetzner node transport and do not invent Cloudflare provider inputs.
- Run `terraform fmt -recursive`, `terraform init -upgrade`, `terraform validate`, and `terraform plan -out=v3-upgrade.tfplan`.
- Run the protected hcloud no-destroy gate from `MIGRATION.md`; it includes
  `hcloud_placement_group` and `hcloud_firewall`.
- Do not apply when the plan has unexplained replacements or destroys.

---

## Configuration Templates

### Minimal Development (Single Node)

```tf
module "kube-hetzner" {
  source  = "kube-hetzner/kube-hetzner/hcloud"
  version = "<LATEST>"  # Always fetch latest!

  hcloud_token = var.hcloud_token

  ssh_public_key  = file("~/.ssh/id_ed25519.pub")
  ssh_private_key = file("~/.ssh/id_ed25519")

  network_region = "eu-central"

  control_plane_nodepools = [
    {
      name        = "control-plane"
      server_type = "cx23"
      location    = "fsn1"
      labels      = []
      taints      = []
      count       = 1
    }
  ]

  agent_nodepools = [
    {
      name        = "worker"
      server_type = "cx23"
      location    = "fsn1"
      labels      = []
      taints      = []
      count       = 0
    }
  ]

  # Single node: disable auto OS upgrades
  automatically_upgrade_os = false
}
```

### Production HA (3 Control Planes + Workers)

```tf
module "kube-hetzner" {
  source  = "kube-hetzner/kube-hetzner/hcloud"
  version = "<LATEST>"

  hcloud_token = var.hcloud_token

  ssh_public_key  = file("~/.ssh/id_ed25519.pub")
  ssh_private_key = file("~/.ssh/id_ed25519")

  network_region = "eu-central"

  control_plane_nodepools = [
    {
      name        = "control-plane"
      server_type = "cx33"
      location    = "fsn1"
      labels      = []
      taints      = []
      count       = 3  # Odd number for quorum!
    }
  ]

  agent_nodepools = [
    {
      name        = "worker"
      server_type = "cx43"
      location    = "fsn1"
      labels      = []
      taints      = []
      count       = 3
    }
  ]

  enable_longhorn = true

  # Security: restrict access to your IP
  firewall_kube_api_source = ["YOUR_IP/32"]
  firewall_ssh_source      = ["YOUR_IP/32"]
}
```

### Private Cluster with NAT Router

```tf
module "kube-hetzner" {
  source  = "kube-hetzner/kube-hetzner/hcloud"
  version = "<LATEST>"

  hcloud_token = var.hcloud_token

  ssh_public_key  = file("~/.ssh/id_ed25519.pub")
  ssh_private_key = file("~/.ssh/id_ed25519")

  network_region = "eu-central"

  enable_control_plane_load_balancer = true

  nat_router = {
    server_type = "cax21"
    location    = "nbg1"
  }

  control_plane_nodepools = [
    {
      name        = "control-plane"
      server_type = "cx33"
      location    = "fsn1"
      labels      = []
      taints      = []
      count       = 3
      # Disable public IPs
      enable_public_ipv4 = false
      enable_public_ipv6 = false
    }
  ]

  agent_nodepools = [
    {
      name        = "worker"
      server_type = "cx43"
      location    = "fsn1"
      labels      = []
      taints      = []
      count       = 3
      enable_public_ipv4 = false
      enable_public_ipv6 = false
    }
  ]

  # Optional: keep control plane LB private too
  control_plane_load_balancer_enable_public_network = false
}
```

### Tailscale Node Transport

Use this when a user wants a single-network cluster with private Tailnet
Terraform/kubeconfig/SSH access, or a private cluster spanning multiple Hetzner
Cloud Networks. Do not use the older external-overlay pattern for Kubernetes
node transport.

```tf
node_transport_mode = "tailscale"

firewall_kube_api_source = null
firewall_ssh_source      = null

tailscale_auth_key = var.tailscale_auth_key
# tailscale_autoscaler_auth_key = var.tailscale_autoscaler_auth_key # Prefer ephemeral reusable key for autoscaler.

tailscale_node_transport = {
  bootstrap_mode  = "cloud_init"
  magicdns_domain = "example-tailnet.ts.net"
  auth = {
    mode = "auth_key"
  }
  routing = {
    # Single-network clusters may set false; network_scope = "external" nodepools need true.
    advertise_node_private_routes = false
  }
}
```

Rules to mention:
- Tailscale mode requires explicit `network_scope = "primary"` or `"external"` on every active agent/autoscaler nodepool. Use `"primary"` when `network_id` is omitted/null; use `"external"` with external `network_id`, including same-root `hcloud_network.*.id`.
- Tailscale node transport is rejected with `cluster_ipv6_cidr` / `service_ipv6_cidr` in this release; keep IPv6 pod/service CIDRs unset on Tailscale clusters.
- Tailnet ACLs must auto-approve advertised Hetzner node-private `/32` routes when external `network_scope` nodepools are used.
- The module disables Tailscale subnet-route SNAT for node/CNI traffic.
- Flannel VXLAN is first supported; Cilium needs the experimental flag; Calico is rejected.
- Managed Hetzner private LBs are fine for single-primary-network clusters; external `network_scope` nodepools need public LB targets or non-Hetzner/private alternatives.
- The module NAT router only gives egress to the primary Hetzner Network; external-network Tailscale nodepools need public egress or an external bootstrap path.
- Large examples live in `examples/tailscale-node-transport/large-scale-200.tf.example` and `examples/tailscale-node-transport/massive-10000-nodes.tf.example`.
- The 200-node static example is `3 control planes + 97 primary agents + 100 agents on one external Network`; both Networks are exactly at Hetzner's 100-attachment limit and placement groups auto-shard to 21 groups.
- The 10,000-total-node reference is `3 control planes + 7 static system agents + 90 primary autoscaled workers + 99 external Networks * 100 autoscaled workers`. It is a quota/design reference, not a casual default.
- The recommended large-cluster exposure model closes public Kubernetes API and SSH, uses no public managed web ingress unless explicitly requested, and relies on Tailnet access. Nodes may still keep public IPv4/IPv6 for Tailscale bootstrap and direct UDP/41641 WireGuard paths; true no-public-IP multinetwork needs private egress plus external Tailscale bootstrap for every external Network.

### Cloudflare Zero Trust External Access

Use this when a user wants Cloudflare policy in front of operator or
human-facing endpoints. Do not present Cloudflare as a kube-hetzner-managed node
transport.

Rules:
- Cloudflare Access/Tunnel can protect kube API, SSH, Rancher, Grafana, or ingress hostnames.
- Cloudflare account resources, DNS records, tunnels, Access policies, WARP enrollment, and service tokens are managed outside kube-hetzner.
- No `node_transport_mode = "cloudflare"` exists, and Cloudflare Mesh/WARP is not supported node transport in v3.
- For kubeconfig through Access, suggest `cloudflared access tcp` or user-owned WARP/private routing.
- Do not set `control_plane_endpoint` to a Cloudflare Access hostname unless every joining node can reach and authenticate to it.
- For secure node transport or +100 node multinetwork, use `node_transport_mode = "tailscale"`.

Reference docs:
- `examples/external-overlay-cloudflare-access/README.md`
- `docs/v3-topology-recommendations.md`

### Cilium with Hubble Observability

```tf
module "kube-hetzner" {
  source  = "kube-hetzner/kube-hetzner/hcloud"
  version = "<LATEST>"

  hcloud_token = var.hcloud_token

  ssh_public_key  = file("~/.ssh/id_ed25519.pub")
  ssh_private_key = file("~/.ssh/id_ed25519")

  network_region = "eu-central"

  # Use Cilium CNI
  cni_plugin = "cilium"

  # Full kube-proxy replacement
  enable_kube_proxy = false

  # Enable Hubble for observability
  cilium_hubble_enabled = true

  control_plane_nodepools = [
    {
      name        = "control-plane"
      server_type = "cx33"
      location    = "fsn1"
      labels      = []
      taints      = []
      count       = 3
    }
  ]

  agent_nodepools = [
    {
      name        = "worker"
      server_type = "cx43"
      location    = "fsn1"
      labels      = []
      taints      = []
      count       = 3
    }
  ]
}
```

### Cost-Optimized ARM Cluster

```tf
module "kube-hetzner" {
  source  = "kube-hetzner/kube-hetzner/hcloud"
  version = "<LATEST>"

  hcloud_token = var.hcloud_token

  ssh_public_key  = file("~/.ssh/id_ed25519.pub")
  ssh_private_key = file("~/.ssh/id_ed25519")

  network_region = "eu-central"

  # ARM servers (CAX) are ~40% cheaper
  control_plane_nodepools = [
    {
      name        = "control-plane"
      server_type = "cax21"  # ARM
      location    = "fsn1"
      labels      = []
      taints      = []
      count       = 3
    }
  ]

  agent_nodepools = [
    {
      name        = "worker-arm"
      server_type = "cax31"  # ARM
      location    = "fsn1"
      labels      = []
      taints      = []
      count       = 3
    }
  ]
}
```

### Super-HA Multi-Location

```tf
module "kube-hetzner" {
  source  = "kube-hetzner/kube-hetzner/hcloud"
  version = "<LATEST>"

  hcloud_token = var.hcloud_token

  ssh_public_key  = file("~/.ssh/id_ed25519.pub")
  ssh_private_key = file("~/.ssh/id_ed25519")

  # Must cover ALL locations used
  network_region = "eu-central"

  # Spread control planes across locations
  control_plane_nodepools = [
    {
      name        = "cp-fsn"
      server_type = "cx33"
      location    = "fsn1"
      labels      = []
      taints      = []
      count       = 1
    },
    {
      name        = "cp-nbg"
      server_type = "cx33"
      location    = "nbg1"
      labels      = []
      taints      = []
      count       = 1
    },
    {
      name        = "cp-hel"
      server_type = "cx33"
      location    = "hel1"
      labels      = []
      taints      = []
      count       = 1
    }
  ]

  # Spread workers too
  agent_nodepools = [
    {
      name        = "worker-fsn"
      server_type = "cx43"
      location    = "fsn1"
      labels      = []
      taints      = []
      count       = 2
    },
    {
      name        = "worker-nbg"
      server_type = "cx43"
      location    = "nbg1"
      labels      = []
      taints      = []
      count       = 2
    },
    {
      name        = "worker-hel"
      server_type = "cx43"
      location    = "hel1"
      labels      = []
      taints      = []
      count       = 2
    }
  ]

  enable_longhorn = true
}
```

---

## Quick Reference

### Variable Lookup

```bash
# Find specific variable
rg -n 'variable "<name>"' variables.tf

# Search by keyword
rg -n -C 3 'description.*<keyword>' variables.tf

# Inspect the complete variable section in docs/llms.md after locating it
```

### GitHub Commands

```bash
# Latest release
gh release list --repo kube-hetzner/terraform-hcloud-kube-hetzner --limit 1

# Search issues
gh issue list --repo kube-hetzner/terraform-hcloud-kube-hetzner --search "<query>" --state all

# View specific issue
gh issue view <number> --repo kube-hetzner/terraform-hcloud-kube-hetzner --comments

# Search discussions
gh api repos/kube-hetzner/terraform-hcloud-kube-hetzner/discussions --jq '.[].title'
```

### Validation

```bash
terraform fmt -recursive
terraform validate
terraform plan  # Check for unexpected changes!
```