typhoon/docs/advanced/nodes.md

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.

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.

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.

Labels: node.kubernetes.io/node=
Taints: <none>

On auto-scaling cloud platforms, you may add 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=v1.22.2"

  # 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=v1.22.2"

  # 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=v1.22.2"

  # 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=v1.22.2"

  # 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.