typhoon/docs/advanced/nodes.md

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# Nodes
Typhoon clusters consist of controller node(s) and a (default) set of worker nodes.
## Overview
Typhoon nodes use the standard set of Kubernetes node labels.
```yaml
Labels: kubernetes.io/arch=amd64
kubernetes.io/hostname=node-name
kubernetes.io/os=linux
```
Controller node(s) are labeled to allow node selection (for rare components that run on controllers) and tainted to prevent ordinary workloads running on controllers.
```yaml
Labels: node.kubernetes.io/controller=true
Taints: node-role.kubernetes.io/controller:NoSchedule
```
Worker nodes are labeled to allow node selection and untainted. Workloads will schedule on worker nodes by default, baring any contraindications.
```yaml
Labels: node.kubernetes.io/node=
Taints: <none>
```
On auto-scaling cloud platforms, you may add [worker pools](/advanced/worker-pools/) with different groups of nodes with their own labels and taints. On platforms like bare-metal, with heterogeneous machines, you may manage node labels and taints per node.
## Node Labels
Add custom initial worker node labels to default workers or worker pool nodes to allow workloads to select among nodes that differ.
=== "Cluster"
```tf
module "yavin" {
source = "git::https://github.com/poseidon/typhoon//google-cloud/fedora-coreos/kubernetes?ref=v1.27.0"
# Google Cloud
cluster_name = "yavin"
region = "us-central1"
dns_zone = "example.com"
dns_zone_name = "example-zone"
# configuration
ssh_authorized_key = local.ssh_key
# optional
worker_count = 2
worker_node_labels = ["pool=default"]
}
```
=== "Worker Pool"
```tf
module "yavin-pool" {
source = "git::https://github.com/poseidon/typhoon//google-cloud/fedora-coreos/kubernetes/workers?ref=v1.27.0"
# Google Cloud
cluster_name = "yavin"
region = "europe-west2"
network = module.yavin.network_name
# configuration
name = "yavin-16x"
kubeconfig = module.yavin.kubeconfig
ssh_authorized_key = local.ssh_key
# optional
worker_count = 1
machine_type = "n1-standard-16"
node_labels = ["pool=big"]
}
```
In the example above, the two default workers would be labeled `pool: default` and the additional worker would be labeled `pool: big`.
## Node Taints
Add custom initial taints on worker pool nodes to indicate a node is unique and should only schedule workloads that explicitly tolerate a given taint key.
!!! warning
Since taints prevent workloads scheduling onto a node, you must decide whether `kube-system` DaemonSets (e.g. flannel, Calico, Cilium) should tolerate your custom taint by setting `daemonset_tolerations`. If you don't list your custom taint(s), important components won't run on these nodes.
=== "Cluster"
```tf
module "yavin" {
source = "git::https://github.com/poseidon/typhoon//google-cloud/fedora-coreos/kubernetes?ref=v1.27.0"
# Google Cloud
cluster_name = "yavin"
region = "us-central1"
dns_zone = "example.com"
dns_zone_name = "example-zone"
# configuration
ssh_authorized_key = local.ssh_key
# optional
worker_count = 2
daemonset_tolerations = ["role"]
}
```
=== "Worker Pool"
```tf
module "yavin-pool" {
source = "git::https://github.com/poseidon/typhoon//google-cloud/fedora-coreos/kubernetes/workers?ref=v1.27.0"
# Google Cloud
cluster_name = "yavin"
region = "europe-west2"
network = module.yavin.network_name
# configuration
name = "yavin-16x"
kubeconfig = module.yavin.kubeconfig
ssh_authorized_key = local.ssh_key
# optional
worker_count = 1
accelerator_type = "nvidia-tesla-p100"
accelerator_count = 1
node_taints = ["role=gpu:NoSchedule"]
}
```
In the example above, the the additional worker would be tainted with `role=gpu:NoSchedule` to prevent workloads scheduling, but `kube-system` components like flannel, Calico, or Cilium would tolerate that custom taint to run there.