Ansible InstanceGroup should add/remove instances

products/compute/ansible.yaml

@@ -230,6 +230,21 @@ overrides: !ruby/object:Provider::ResourceOverrides
       timeoutSec: !ruby/object:Provider::Ansible::PropertyOverride
         aliases:
           - timeout_seconds
+  InstanceGroup: !ruby/object:Provider::Ansible::ResourceOverride
+    properties:
+      instances: !ruby/object:Provider::Ansible::PropertyOverride
+        version_added: '2.7'
+        exclude: false
+    update: |
+      instance = InstanceLogic(module)
+      instance.run()
+    post_action: |
+      if fetch:
+          instance = InstanceLogic(module)
+          instance.run()
+          fetch.update({'instances': instance.list_instances()})
+    provider_helpers:
+      - 'products/compute/helpers/python/instancegroup_instances.py'
   Instance: !ruby/object:Provider::Ansible::ResourceOverride
     provider_helpers:
       - 'products/compute/helpers/python/provider_instance.py'

products/compute/api.yaml

@@ -1866,6 +1866,20 @@ objects:
         imports: 'name'
         description: 'A reference to the zone where the instance group resides.'
         required: true
+      - !ruby/object:Api::Type::Array
+        name: 'instances'
+        description: |
+          The list of instances associated with this InstanceGroup.
+          All instances must be created before being added to an InstanceGroup.
+          All instances not in this list will be removed from the InstanceGroup
+          and will not be deleted.
+          Only the full identifier of the instance will be returned.
+        exclude: true
+        item_type: !ruby/object:Api::Type::ResourceRef
+          name: 'instance'
+          description: 'An instance being added to the InstanceGroup'
+          resource: 'Instance'
+          imports: 'selfLink'
     properties:
       - !ruby/object:Api::Type::Time
         name: 'creationTimestamp'

products/compute/helpers/python/instancegroup_instances.py

@@ -0,0 +1,64 @@
+<%
+# Instance Logic handling for Instance Groups
+# This code handles the adding + removing of instances from an instance group.
+# It should be run after all normal create/update/delete logic.
+
+-%>
+class InstanceLogic(object):
+    def __init__(self, module):
+        self.module = module
+        self.current_instances = self.list_instances()
+        self.module_instances = []
+
+        # Transform module list of instances (dicts of instance responses) into a list of selfLinks.
+        instances = self.module.params.get('instances')
+        if instances:
+            for instance in instances:
+                self.module_instances.append(replace_resource_dict(instance, 'selfLink'))
+
+    def run(self):
+        # Find all instances to add and add them
+        instances_to_add = list(set(self.module_instances) - set(self.current_instances))
+        if instances_to_add:
+            self.add_instances(instances_to_add)
+
+        # Find all instances to remove and remove them
+        instances_to_remove = list(set(self.current_instances) - set(self.module_instances))
+        if instances_to_remove:
+            self.remove_instances(instances_to_remove)
+
+    def list_instances(self):
+        auth = GcpSession(self.module, 'compute')
+        response = return_if_object(self.module, auth.post(self._list_instances_url(), {'instanceState': 'ALL'}),
+                                    'compute#instanceGroupsListInstances')
+
+        # Transform instance list into a list of selfLinks for diffing with module parameters
+        instances = []
+        for instance in response.get('items', []):
+            instances.append(instance['instance'])
+        return instances
+
+    def add_instances(self, instances):
+        auth = GcpSession(self.module, 'compute')
+        wait_for_operation(self.module, auth.post(self._add_instances_url(), self._build_request(instances)))
+
+    def remove_instances(self, instances):
+        auth = GcpSession(self.module, 'compute')
+        wait_for_operation(self.module, auth.post(self._remove_instances_url(), self._build_request(instances)))
+
+    def _list_instances_url(self):
+        return "https://www.googleapis.com/compute/v1/projects/{project}/zones/{zone}/instanceGroups/{name}/listInstances".format(**self.module.params)
+
+    def _remove_instances_url(self):
+        return "https://www.googleapis.com/compute/v1/projects/{project}/zones/{zone}/instanceGroups/{name}/removeInstances".format(**self.module.params)
+
+    def _add_instances_url(self):
+        return "https://www.googleapis.com/compute/v1/projects/{project}/zones/{zone}/instanceGroups/{name}/addInstances".format(**self.module.params)
+
+    def _build_request(self, instances):
+        request = {
+            'instances': []
+        }
+        for instance in instances:
+            request['instances'].append({'instance': instance})
+        return request

provider/ansible/resource_override.rb

@@ -27,6 +27,7 @@ module OverrideProperties
       attr_reader :hidden
       attr_reader :imports
       attr_reader :post_create
+      attr_reader :post_action
       attr_reader :provider_helpers
       attr_reader :return_if_object
       attr_reader :unwrap_resource
@@ -60,6 +61,7 @@ def validate
         check_optional_property :hidden, ::Array
         check_property :imports, ::Array
         check_optional_property :post_create, ::String
+        check_optional_property :post_action, ::String
         check_property :provider_helpers, ::Array
         check_optional_property :return_if_object, ::String
         check_optional_property :update, ::String

templates/ansible/resource.erb

@@ -196,6 +196,9 @@ def main():
         else:
             fetch = {}
 
+<% if object.post_action -%>
+<%= lines(indent(object.post_action, 4)) -%>
+<% end # ifobject.post_create -%>
     fetch.update({'changed': changed})
 <% end # object.readonly -%>