Improve apiserver backend service zone spanning

* google_compute_backend_services use nested blocks to define
backends (instance groups heterogeneous controllers)
* Use Terraform v0.12.x dynamic blocks so the apiserver backend
service can refer to (up to zone-many) controller instance groups
* Previously, with Terraform v0.11.x, the apiserver backend service
had to list a fixed set of backends to span controller nodes across
zones in multi-controller setups. 3 backends were used because each
GCP region offered at least 3 zones. Single-controller clusters had
the cosmetic ugliness of unused instance groups
* Allow controllers to span more than 3 zones if avilable in a
region (e.g. currently only us-central1, with 4 zones)

Related:

* https://www.terraform.io/docs/providers/google/r/compute_backend_service.html
* https://www.terraform.io/docs/configuration/expressions.html#dynamic-blocks
This commit is contained in:
Dalton Hubble 2019-07-05 19:21:05 -07:00
parent 8d373b5850
commit 3fcb04f68c
3 changed files with 12 additions and 18 deletions

View File

@ -6,6 +6,11 @@ Notable changes between versions.
* Update Calico from v3.7.3 to [v3.7.4](https://docs.projectcalico.org/v3.7/release-notes/)
#### Google Cloud
* Allow controller nodes to span more than 3 zones if available in a region ([#504](https://github.com/poseidon/typhoon/pull/504))
* Eliminate extraneous controller instance groups in single-controller clusters ([#504](https://github.com/poseidon/typhoon/pull/504))
#### Addons
* Update Grafana from v6.2.4 to v6.2.5

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@ -45,16 +45,11 @@ resource "google_compute_backend_service" "apiserver" {
timeout_sec = "300"
# controller(s) spread across zonal instance groups
backend {
group = google_compute_instance_group.controllers[0].self_link
}
backend {
group = google_compute_instance_group.controllers[1].self_link
}
backend {
group = google_compute_instance_group.controllers[2].self_link
dynamic "backend" {
for_each = google_compute_instance_group.controllers
content {
group = backend.value.self_link
}
}
health_checks = [google_compute_health_check.apiserver.self_link]
@ -64,11 +59,7 @@ resource "google_compute_backend_service" "apiserver" {
resource "google_compute_instance_group" "controllers" {
count = length(local.zones)
name = format(
"%s-controllers-%s",
var.cluster_name,
element(local.zones, count.index),
)
name = format("%s-controllers-%s", var.cluster_name, element(local.zones, count.index))
zone = element(local.zones, count.index)
named_port {

View File

@ -20,9 +20,7 @@ data "google_compute_zones" "all" {
}
locals {
# TCP proxy load balancers require a fixed number of zonal backends. Spread
# controllers over up to 3 zones, since all GCP regions have at least 3.
zones = slice(data.google_compute_zones.all.names, 0, 3)
zones = data.google_compute_zones.all.names
controllers_ipv4_public = google_compute_instance.controllers.*.network_interface.0.access_config.0.nat_ip
}