Added support for Stateful Managed Instance Groups (#367)

* First iteration updates

* All tests passing

* Updated README and var descriptions

* Updated README

* Updated example README

* Consolidated stateful vars

* consolidated stateful vars

* Updated README

* Requested changes to try

* Fixed README examples and try

Co-authored-by: Ludovico Magnocavallo <ludomagno@google.com>

tests/modules/compute_mig/fixture/main.tf

@@ -14,6 +14,15 @@
  * limitations under the License.
  */
 
+# Used in stateful disk test
+resource "google_compute_disk" "default" {
+  name                      = "test-disk"
+  type                      = "pd-ssd"
+  zone                      = "europe-west1-c"
+  image                     = "debian-9-stretch-v20200805"
+  physical_block_size_bytes = 4096
+}
+
 module "test" {
   source      = "../../../../modules/compute-mig"
   project_id  = "my-project"
@@ -28,6 +37,8 @@ module "test" {
   health_check_config = var.health_check_config
   named_ports         = var.named_ports
   regional            = var.regional
-  update_policy       = var.update_policy
-  versions            = var.versions
+  stateful_config     = var.stateful_config
+
+  update_policy = var.update_policy
+  versions      = var.versions
 }

tests/modules/compute_mig/fixture/variables.tf

@@ -60,6 +60,37 @@ variable "regional" {
   default = false
 }
 
+variable "stateful_config" {
+  description = "Stateful configuration can be done by individual instances or for all instances in the MIG. They key in per_instance_config is the name of the specific instance. The key of the stateful_disks is the 'device_name' field of the resource. Please note that device_name is defined at the OS mount level, unlike the disk name."
+  type = object({
+    per_instance_config = map(object({
+      #name is the key
+      #name = string
+      stateful_disks = map(object({
+        #device_name is the key
+        source      = string
+        mode        = string # READ_WRITE | READ_ONLY 
+        delete_rule = string # NEVER | ON_PERMANENT_INSTANCE_DELETION
+      }))
+      metadata = map(string)
+      update_config = object({
+        minimal_action                   = string # NONE | REPLACE | RESTART | REFRESH
+        most_disruptive_allowed_action   = string # REPLACE | RESTART | REFRESH | NONE
+        remove_instance_state_on_destroy = bool
+      })
+    }))
+
+    mig_config = object({
+      stateful_disks = map(object({
+        #device_name is the key
+        delete_rule = string # NEVER | ON_PERMANENT_INSTANCE_DELETION
+      }))
+    })
+
+  })
+  default = null
+}
+
 variable "update_policy" {
   type = object({
     type                 = string # OPPORTUNISTIC | PROACTIVE

tests/modules/compute_mig/test_plan.py

@@ -24,6 +24,7 @@ def test_defaults(plan_runner):
   "Test variable defaults."
   _, resources = plan_runner(FIXTURES_DIR)
   assert len(resources) == 1
+  print(resources[0]['type'])
   mig = resources[0]
   assert mig['type'] == 'google_compute_instance_group_manager'
   assert mig['values']['target_size'] == 2
@@ -35,7 +36,6 @@ def test_defaults(plan_runner):
   assert mig['values']['target_size'] == 2
   assert mig['values']['region']
 
-
 def test_health_check(plan_runner):
   "Test health check resource."
   health_check_config = '{type="tcp", check={port=80}, config=null, logging=false}'
@@ -75,3 +75,81 @@ def test_autoscaler(plan_runner):
   assert len(resources) == 2
   autoscaler = resources[0]
   assert autoscaler['type'] == 'google_compute_region_autoscaler'
+  
+def test_stateful_mig(plan_runner):
+  "Test stateful instances - mig."
+
+  stateful_config = (
+    '{'
+      'per_instance_config = {},'
+      'mig_config = {'
+        'stateful_disks = {'
+          'persistent-disk-1 = {delete_rule="NEVER"}'
+        '}' 
+      '}'
+    '}'
+  )
+  _, resources = plan_runner(
+      FIXTURES_DIR, stateful_config=stateful_config)
+  assert len(resources) == 1
+  statefuldisk = resources[0]
+  assert statefuldisk['type'] == 'google_compute_instance_group_manager'
+  assert statefuldisk['values']['stateful_disk'] == [{
+      'device_name': 'persistent-disk-1',
+      'delete_rule': 'NEVER',
+  }]
+  
+def test_stateful_instance(plan_runner):
+  "Test stateful instances - instance."
+  stateful_config = (
+    '{'
+      'per_instance_config = {'
+        'instance-1 = {'
+          'stateful_disks = {'
+            'persistent-disk-1 = {'
+              'source = "test-disk",' 
+              'mode = "READ_ONLY",'
+              'delete_rule= "NEVER",'
+            '},'
+          '},'
+          'metadata = {'
+            'foo = "bar"'
+          '},'
+          'update_config = {'
+            'minimal_action                   = "NONE",'
+            'most_disruptive_allowed_action   = "REPLACE",'
+            'remove_instance_state_on_destroy = false,'
+            
+          '},'
+        '},'
+      '},'
+      'mig_config = {'
+        'stateful_disks = {'
+          'persistent-disk-1 = {delete_rule="NEVER"}'
+        '}' 
+      '}'
+    '}'
+  )
+  _, resources = plan_runner(
+      FIXTURES_DIR, stateful_config=stateful_config)
+  assert len(resources) == 2
+  instanceconfig = resources[0]
+  assert instanceconfig['type'] == 'google_compute_instance_group_manager'
+  instanceconfig = resources[1]
+  assert instanceconfig['type'] == 'google_compute_per_instance_config'
+  
+  assert instanceconfig['values']['preserved_state'] == [{
+      'disk': [{
+        'device_name': 'persistent-disk-1',
+        'delete_rule': 'NEVER',
+        'source': 'test-disk',
+        'mode': 'READ_ONLY',
+      }],
+      'metadata': {
+        'foo': 'bar'
+      }
+  }]
+
+  assert instanceconfig['values']['minimal_action'] == 'NONE'
+  assert instanceconfig['values']['most_disruptive_allowed_action'] == 'REPLACE'
+  assert instanceconfig['values']['remove_instance_state_on_destroy'] == False