Draft: Autoscaling

cluster/main.tf

@@ -62,7 +62,7 @@ resource "digitalocean_ssh_key" "default" {
 
 resource "digitalocean_droplet" "nomad_server" {
   count = var.nomad_servers_count
-  image = data.digitalocean_images.cluster_server.images[0].id
+  image = var.snapshot
   # Consul members name must be unique
   name   = "nomad-cluster-server-${count.index}"
   region = var.do_region
@@ -78,7 +78,7 @@ resource "digitalocean_droplet" "nomad_server" {
 
 resource "digitalocean_droplet" "nomad_client" {
   count = var.nomad_clients_count
-  image = data.digitalocean_images.cluster_server.images[0].id
+  image = var.snapshot
   # Consul members name must be unique
   name   = "nomad-cluster-general-client-${count.index}"
   region = var.do_region
@@ -93,7 +93,7 @@ resource "digitalocean_droplet" "nomad_client" {
 }
 
 resource "digitalocean_droplet" "ingress_client" {
-  image = data.digitalocean_images.cluster_server.images[0].id
+  image = var.snapshot
   # Consul members name must be unique
   name     = "nomad-cluster-ingress"
   region   = var.do_region

cluster/outputs.tf

@@ -7,6 +7,11 @@ output "server_droplet_ips" {
   value = join(",", digitalocean_droplet.nomad_server[*].ipv4_address)
 }
 
+output "nomad_address" {
+  // This makes the provider definition a bit simpiler
+  value = "http://${digitalocean_droplet.nomad_server[0].ipv4_address}:4646"
+}
+
 output "ingress_droplet_ip" {
   value = digitalocean_droplet.ingress_client.ipv4_address
 }

cluster/variables.tf

@@ -2,6 +2,10 @@ variable "do_token" {
   type = string
 }
 
+variable "snapshot" {
+  type = string
+}
+
 variable "do_region" {
   type    = string
   default = "lon1"

image/main.tf

@@ -0,0 +1,48 @@
+terraform {
+  required_providers {
+    digitalocean = {
+      source  = "digitalocean/digitalocean"
+      version = "2.8.0"
+    }
+  }
+}
+
+
+locals {
+  build_image = var.image == ""
+  image       = local.build_image ? data.digitalocean_image.built[0] : data.digitalocean_image.existing[0]
+}
+
+resource "random_pet" "name" {
+  count = local.build_image ? 1 : 0
+}
+
+resource "null_resource" "packer_build" {
+  count = local.build_image ? 1 : 0
+
+  provisioner "local-exec" {
+    command = <<EOF
+cd ${path.module}/packer && \
+  packer build -force \
+    -var 'name=hashi-${random_pet.name[0].id}' \
+    -var 'region=${var.region}' \
+    -var 'token=${var.do_token}' \
+    do-packer.pkr.hcl
+EOF
+  }
+}
+
+data "digitalocean_image" "built" {
+  depends_on = [null_resource.packer_build]
+  count      = local.build_image ? 1 : 0
+  name       = "hashi-${random_pet.name[0].id}"
+}
+
+data "digitalocean_image" "existing" {
+  count = local.build_image ? 0 : 1
+  name  = var.image
+}
+
+output "snapshot_id" {
+  value = local.image.id
+}

image/variables.tf

@@ -0,0 +1,10 @@
+variable "do_token" {}
+
+variable "region" {
+  type = string
+}
+
+variable "image" {
+  type    = string
+  default = ""
+}

main.tf

@@ -0,0 +1,53 @@
+terraform {
+  required_providers {
+    digitalocean = {
+      source  = "digitalocean/digitalocean"
+      version = "2.8.0"
+    }
+  }
+}
+
+provider "digitalocean" {
+  token = var.do_token
+}
+
+provider "nomad" {
+  address = module.cluster.nomad_address
+}
+
+# Pre-flight check.
+resource "null_resource" "preflight_check" {
+  provisioner "local-exec" {
+    command = <<EOF
+curl --version && \
+packer --version && \
+nomad --version
+EOF
+  }
+}
+
+module "image" {
+  depends_on = [null_resource.preflight_check]
+}
+
+
+module "cluster" {
+  depends_on = [null_resource.preflight_check]
+  source     = "./cluster"
+  do_token    = var.do_token
+  snapshot_id = module.image.snapshot_id
+  ssh_key     = var.ssh_key
+  region      = var.region
+  ip_range    = var.ip_range
+}
+
+
+module "jobs" {
+  depends_on = [null_resource.preflight_check]
+}
+
+module "vault" {
+  depends_on = [null_resource.preflight_check]
+}
+
+

shared/config/nomad.hcl

@@ -24,4 +24,12 @@ plugin "raw_exec" {
   config {
     enabled = true
   }
+}
+
+telemetry {
+  collection_interval = "1s"
+  disable_hostname = true
+  prometheus_metrics = true
+  publish_allocation_metrics = true
+  publish_node_metrics = true
 }

shared/config/nomad_client.hcl

@@ -20,3 +20,11 @@ vault {
   enabled = true
   address = "http://active.vault.service.consul:8200"
 }
+
+telemetry {
+  collection_interval = "1s"
+  disable_hostname = true
+  prometheus_metrics = true
+  publish_allocation_metrics = true
+  publish_node_metrics = true
+}