Load balancer to target servers with specific labels?

[mixman]

Currently the load balancer targets all the agent_nodepools[] by default. This leads to uncertain latency with nodes in Finland and Germany. Wondering on best way to have country specific LB only use nodes from same country. The Hetzner load balancer can target servers with specific labels using a label_selector:

resource "hcloud_load_balancer_target" "load_balancer_target" {
  type             = "label_selector"
  label_selector   = "country_code in (fi,dev)"

What is the most straightforward way to have agent_nodepools[] labels added to hcloud_server (agent_nodepools[].labels seem to apply to k8s nodes) and instruct the hcloud_load_balancer to target those specific labels only?

Specifying the label_selector value in kube.tf as a variable would be a start, then a bit perplexed on how to label the servers to finish the job.

[mixman]

I looked at the code and couldn't figure out how the hcloud_load_balancer is even created to be able to modify its label_selector. 😅

Is the templates/ccm.yaml.tpl involved? The resource seems to be kubectl get service traefik -n traefik (k3s-traefik).
How https://registry.terraform.io/providers/hetznercloud/hcloud/latest/docs/resources/load_balancer maps to https://github.com/hetznercloud/hcloud-cloud-controller-manager/blob/main/docs/load_balancers.md metadata.annotations is also unclear to me.
There seems to be a load-balancer.hetzner.cloud/node-selector (https://github.com/hetznercloud/hcloud-cloud-controller-manager/blob/main/internal/annotation/load_balancer.go) annotation and providing this to traefik_values could solve the node_selector -bit.

What would be the cleanest way to add labels to the agent_nodepools[] themselves? Introducing a new vm_labels dictionary variable and modifying agents.tf like labels = merge(local.labels, local.labels_agent_node, each.value.vm_labels)?

[mixman]

Given modifying traefik_values annotations works to modify load-balancer.hetzner.cloud/node-selector = "location in (nbg1)", then this should be enough of a change:

# agents.tf, module "agents":
  labels = merge(local.labels, local.labels_agent_node, {"location": each.value.location})

[mixman]

Solved in #1191