feat: Add support for configuring autoscaler scale_in on MIGs (#166)

Author: kir4h

autogen/main.tf.tmpl

@@ -25,7 +25,8 @@ locals {
     default = data.google_compute_zones.available.names
     user    = var.distribution_policy_zones
   }
-  distribution_policy_zones = local.distribution_policy_zones_base[length(var.distribution_policy_zones) == 0 ? "default" : "user"]
+  distribution_policy_zones    = local.distribution_policy_zones_base[length(var.distribution_policy_zones) == 0 ? "default" : "user"]
+  autoscaling_scale_in_enabled = var.autoscaling_scale_in_control.fixed_replicas != null || var.autoscaling_scale_in_control.percent_replicas != null
 }
 
 data "google_compute_zones" "available" {
@@ -129,6 +130,16 @@ resource "google_compute_region_autoscaler" "autoscaler" {
     max_replicas    = var.max_replicas
     min_replicas    = var.min_replicas
     cooldown_period = var.cooldown_period
+    dynamic "scale_in_control" {
+      for_each = local.autoscaling_scale_in_enabled ? [var.autoscaling_scale_in_control] : []
+      content {
+        max_scaled_in_replicas {
+          fixed   = lookup(scale_in_control.value, "fixed_replicas", null)
+          percent = lookup(scale_in_control.value, "percent_replicas", null)
+        }
+        time_window_sec = lookup(scale_in_control.value, "time_window_sec", null)
+      }
+    }
     dynamic "cpu_utilization" {
       for_each = var.autoscaling_cpu
       content {

autogen/variables.tf.tmpl

@@ -184,6 +184,20 @@ variable "autoscaling_lb" {
   default     = []
 }
 
+variable "autoscaling_scale_in_control" {
+  description = "Autoscaling, scale-in control block. https://www.terraform.io/docs/providers/google/r/compute_autoscaler.html#scale_in_control"
+  type = object({
+    fixed_replicas   = number
+    percent_replicas = number
+    time_window_sec  = number
+  })
+  default = {
+    fixed_replicas   = null
+    percent_replicas = null
+    time_window_sec  = null
+  }
+}
+
 ##########################
 
 variable "network" {

examples/mig/full/main.tf

@@ -76,12 +76,13 @@ module "mig" {
   health_check = var.health_check
 
   /* autoscaler */
-  autoscaling_enabled = var.autoscaling_enabled
-  max_replicas        = var.max_replicas
-  min_replicas        = var.min_replicas
-  cooldown_period     = var.cooldown_period
-  autoscaling_cpu     = var.autoscaling_cpu
-  autoscaling_metric  = var.autoscaling_metric
-  autoscaling_lb      = var.autoscaling_lb
+  autoscaling_enabled          = var.autoscaling_enabled
+  max_replicas                 = var.max_replicas
+  min_replicas                 = var.min_replicas
+  cooldown_period              = var.cooldown_period
+  autoscaling_cpu              = var.autoscaling_cpu
+  autoscaling_metric           = var.autoscaling_metric
+  autoscaling_lb               = var.autoscaling_lb
+  autoscaling_scale_in_control = var.autoscaling_scale_in_control
 }
 

examples/mig/full/variables.tf

@@ -266,6 +266,20 @@ variable "autoscaling_lb" {
   default     = []
 }
 
+variable "autoscaling_scale_in_control" {
+  description = "Autoscaling, scale-in control block. https://www.terraform.io/docs/providers/google/r/compute_autoscaler.html#scale_in_control"
+  type = object({
+    fixed_replicas   = number
+    percent_replicas = number
+    time_window_sec  = number
+  })
+  default = {
+    fixed_replicas   = 0
+    percent_replicas = 30
+    time_window_sec  = 600
+  }
+}
+
 variable "autoscaling_enabled" {
   description = "Creates an autoscaler for the managed instance group"
   type        = bool

modules/mig/README.md

@@ -22,6 +22,7 @@ The current version is 2.X. The following guides are available to assist with up
 | autoscaling\_enabled | Creates an autoscaler for the managed instance group | `string` | `"false"` | no |
 | autoscaling\_lb | Autoscaling, load balancing utilization policy block as single element array. https://www.terraform.io/docs/providers/google/r/compute_autoscaler.html#load_balancing_utilization | `list(map(number))` | `[]` | no |
 | autoscaling\_metric | Autoscaling, metric policy block as single element array. https://www.terraform.io/docs/providers/google/r/compute_autoscaler.html#metric | <pre>list(object({<br>    name   = string<br>    target = number<br>    type   = string<br>  }))</pre> | `[]` | no |
+| autoscaling\_scale\_in\_control | Autoscaling, scale-in control block. https://www.terraform.io/docs/providers/google/r/compute_autoscaler.html#scale_in_control | <pre>object({<br>    fixed_replicas   = number<br>    percent_replicas = number<br>    time_window_sec  = number<br>  })</pre> | <pre>{<br>  "fixed_replicas": null,<br>  "percent_replicas": null,<br>  "time_window_sec": null<br>}</pre> | no |
 | cooldown\_period | The number of seconds that the autoscaler should wait before it starts collecting information from a new instance. | `number` | `60` | no |
 | distribution\_policy\_zones | The distribution policy, i.e. which zone(s) should instances be create in. Default is all zones in given region. | `list(string)` | `[]` | no |
 | health\_check | Health check to determine whether instances are responsive and able to do work | <pre>object({<br>    type                = string<br>    initial_delay_sec   = number<br>    check_interval_sec  = number<br>    healthy_threshold   = number<br>    timeout_sec         = number<br>    unhealthy_threshold = number<br>    response            = string<br>    proxy_header        = string<br>    port                = number<br>    request             = string<br>    request_path        = string<br>    host                = string<br>  })</pre> | <pre>{<br>  "check_interval_sec": 30,<br>  "healthy_threshold": 1,<br>  "host": "",<br>  "initial_delay_sec": 30,<br>  "port": 80,<br>  "proxy_header": "NONE",<br>  "request": "",<br>  "request_path": "/",<br>  "response": "",<br>  "timeout_sec": 10,<br>  "type": "",<br>  "unhealthy_threshold": 5<br>}</pre> | no |

modules/mig/main.tf

@@ -25,7 +25,8 @@ locals {
     default = data.google_compute_zones.available.names
     user    = var.distribution_policy_zones
   }
-  distribution_policy_zones = local.distribution_policy_zones_base[length(var.distribution_policy_zones) == 0 ? "default" : "user"]
+  distribution_policy_zones    = local.distribution_policy_zones_base[length(var.distribution_policy_zones) == 0 ? "default" : "user"]
+  autoscaling_scale_in_enabled = var.autoscaling_scale_in_control.fixed_replicas != null || var.autoscaling_scale_in_control.percent_replicas != null
 }
 
 data "google_compute_zones" "available" {
@@ -113,6 +114,16 @@ resource "google_compute_region_autoscaler" "autoscaler" {
     max_replicas    = var.max_replicas
     min_replicas    = var.min_replicas
     cooldown_period = var.cooldown_period
+    dynamic "scale_in_control" {
+      for_each = local.autoscaling_scale_in_enabled ? [var.autoscaling_scale_in_control] : []
+      content {
+        max_scaled_in_replicas {
+          fixed   = lookup(scale_in_control.value, "fixed_replicas", null)
+          percent = lookup(scale_in_control.value, "percent_replicas", null)
+        }
+        time_window_sec = lookup(scale_in_control.value, "time_window_sec", null)
+      }
+    }
     dynamic "cpu_utilization" {
       for_each = var.autoscaling_cpu
       content {

modules/mig/variables.tf

@@ -169,6 +169,20 @@ variable "autoscaling_lb" {
   default     = []
 }
 
+variable "autoscaling_scale_in_control" {
+  description = "Autoscaling, scale-in control block. https://www.terraform.io/docs/providers/google/r/compute_autoscaler.html#scale_in_control"
+  type = object({
+    fixed_replicas   = number
+    percent_replicas = number
+    time_window_sec  = number
+  })
+  default = {
+    fixed_replicas   = null
+    percent_replicas = null
+    time_window_sec  = null
+  }
+}
+
 ##########################
 
 variable "network" {

modules/mig_with_percent/README.md

@@ -21,6 +21,7 @@ The current version is 2.X. The following guides are available to assist with up
 | autoscaling\_enabled | Creates an autoscaler for the managed instance group | `string` | `"false"` | no |
 | autoscaling\_lb | Autoscaling, load balancing utilization policy block as single element array. https://www.terraform.io/docs/providers/google/r/compute_autoscaler.html#load_balancing_utilization | `list(map(number))` | `[]` | no |
 | autoscaling\_metric | Autoscaling, metric policy block as single element array. https://www.terraform.io/docs/providers/google/r/compute_autoscaler.html#metric | <pre>list(object({<br>    name   = string<br>    target = number<br>    type   = string<br>  }))</pre> | `[]` | no |
+| autoscaling\_scale\_in\_control | Autoscaling, scale-in control block. https://www.terraform.io/docs/providers/google/r/compute_autoscaler.html#scale_in_control | <pre>object({<br>    fixed_replicas   = number<br>    percent_replicas = number<br>    time_window_sec  = number<br>  })</pre> | <pre>{<br>  "fixed_replicas": null,<br>  "percent_replicas": null,<br>  "time_window_sec": null<br>}</pre> | no |
 | cooldown\_period | The number of seconds that the autoscaler should wait before it starts collecting information from a new instance. | `number` | `60` | no |
 | distribution\_policy\_zones | The distribution policy, i.e. which zone(s) should instances be create in. Default is all zones in given region. | `list(string)` | `[]` | no |
 | health\_check | Health check to determine whether instances are responsive and able to do work | <pre>object({<br>    type                = string<br>    initial_delay_sec   = number<br>    check_interval_sec  = number<br>    healthy_threshold   = number<br>    timeout_sec         = number<br>    unhealthy_threshold = number<br>    response            = string<br>    proxy_header        = string<br>    port                = number<br>    request             = string<br>    request_path        = string<br>    host                = string<br>  })</pre> | <pre>{<br>  "check_interval_sec": 30,<br>  "healthy_threshold": 1,<br>  "host": "",<br>  "initial_delay_sec": 30,<br>  "port": 80,<br>  "proxy_header": "NONE",<br>  "request": "",<br>  "request_path": "/",<br>  "response": "",<br>  "timeout_sec": 10,<br>  "type": "",<br>  "unhealthy_threshold": 5<br>}</pre> | no |

modules/mig_with_percent/main.tf

@@ -25,7 +25,8 @@ locals {
     default = data.google_compute_zones.available.names
     user    = var.distribution_policy_zones
   }
-  distribution_policy_zones = local.distribution_policy_zones_base[length(var.distribution_policy_zones) == 0 ? "default" : "user"]
+  distribution_policy_zones    = local.distribution_policy_zones_base[length(var.distribution_policy_zones) == 0 ? "default" : "user"]
+  autoscaling_scale_in_enabled = var.autoscaling_scale_in_control.fixed_replicas != null || var.autoscaling_scale_in_control.percent_replicas != null
 }
 
 data "google_compute_zones" "available" {
@@ -122,6 +123,16 @@ resource "google_compute_region_autoscaler" "autoscaler" {
     max_replicas    = var.max_replicas
     min_replicas    = var.min_replicas
     cooldown_period = var.cooldown_period
+    dynamic "scale_in_control" {
+      for_each = local.autoscaling_scale_in_enabled ? [var.autoscaling_scale_in_control] : []
+      content {
+        max_scaled_in_replicas {
+          fixed   = lookup(scale_in_control.value, "fixed_replicas", null)
+          percent = lookup(scale_in_control.value, "percent_replicas", null)
+        }
+        time_window_sec = lookup(scale_in_control.value, "time_window_sec", null)
+      }
+    }
     dynamic "cpu_utilization" {
       for_each = var.autoscaling_cpu
       content {

modules/mig_with_percent/variables.tf

@@ -177,6 +177,20 @@ variable "autoscaling_lb" {
   default     = []
 }
 
+variable "autoscaling_scale_in_control" {
+  description = "Autoscaling, scale-in control block. https://www.terraform.io/docs/providers/google/r/compute_autoscaler.html#scale_in_control"
+  type = object({
+    fixed_replicas   = number
+    percent_replicas = number
+    time_window_sec  = number
+  })
+  default = {
+    fixed_replicas   = null
+    percent_replicas = null
+    time_window_sec  = null
+  }
+}
+
 ##########################
 
 variable "network" {