Fully support mixed instance policy

Previously, setting instances_distribution was not supported.
instances_distribution should be supported, to allow users to enable
spot instances within their mixed instance ASGs.

Note: The type and significance of the mixed_instance_policy has
changed. It now captures all of the mixed_instance_policy configuration
parameters, rather than just a list of instance types.

Fixes ansible-collections#231

plugins/modules/ec2_asg.py

@@ -93,6 +93,60 @@
           - A list of instance_types.
         type: list
         elements: str
+        required: false
+      instances_distribution:
+        description:
+          - >-
+            Specifies the distribution of On-Demand Instances and Spot Instances, the maximum price
+            to pay for Spot Instances, and how the Auto Scaling group allocates instance types
+            to fulfill On-Demand and Spot capacity.
+          - 'See also U(https://docs.aws.amazon.com/autoscaling/ec2/APIReference/API_InstancesDistribution.html)'
+        required: false
+        type: dict
+        suboptions:
+          on_demand_allocation_strategy:
+            description:
+              - Indicates how to allocate instance types to fulfill On-Demand capacity.
+            type: str
+            required: false
+          on_demand_base_capacity:
+            description:
+              - >-
+                The minimum amount of the Auto Scaling group's capacity that must be fulfilled by On-Demand
+                Instances. This base portion is provisioned first as your group scales.
+              - >-
+                Default if not set is 0. If you leave it set to 0, On-Demand Instances are launched as a
+                percentage of the Auto Scaling group's desired capacity, per the OnDemandPercentageAboveBaseCapacity setting.
+            type: int
+            required: false
+          on_demand_percentage_above_base_capacity:
+            description:
+              - Controls the percentages of On-Demand Instances and Spot Instances for your additional capacity beyond OnDemandBaseCapacity.
+              - Default if not set is 100. If you leave it set to 100, the percentages are 100% for On-Demand Instances and 0% for Spot Instances.
+              - 'Valid range: 0 to 100'
+            type: int
+            required: false
+          spot_allocation_strategy:
+            description:
+              - Indicates how to allocate instances across Spot Instance pools.
+            type: str
+            required: false
+          spot_instance_pools:
+            description:
+              - >-
+                The number of Spot Instance pools across which to allocate your Spot Instances. The Spot pools are determined from
+                the different instance types in the Overrides array of LaunchTemplate. Default if not set is 2.
+              - Used only when the Spot allocation strategy is lowest-price.
+              - 'Valid Range: Minimum value of 1. Maximum value of 20.'
+            type: int
+            required: false
+          spot_max_price:
+            description:
+              - The maximum price per unit hour that you are willing to pay for a Spot Instance.
+              - If you leave the value of this parameter blank (which is the default), the maximum Spot price is set at the On-Demand price.
+              - To remove a value that you previously set, include the parameter but leave the value blank.
+            type: str
+            required: false
     type: dict
   placement_group:
     description:
@@ -339,6 +393,9 @@
             - t3a.large
             - t3.large
             - t2.large
+        instances_distribution:
+            on_demand_percentage_above_base_capacity: 0
+            spot_allocation_strategy: capacity-optimized
     min_size: 1
     max_size: 10
     desired_capacity: 5
@@ -448,10 +505,32 @@
     type: int
     sample: 1
 mixed_instance_policy:
-    description: Returns the list of instance types if a mixed instance policy is set.
+    description: Returns the dictionary representation of the mixed instance policy.
     returned: success
-    type: list
-    sample: ["t3.micro", "t3a.micro"]
+    type: dict
+    sample: {
+        "InstancesDistribution": {
+            "OnDemandAllocationStrategy": "prioritized",
+            "OnDemandBaseCapacity": 0,
+            "OnDemandPercentageAboveBaseCapacity": 0,
+            "SpotAllocationStrategy": "capacity-optimized"
+        },
+        "LaunchTemplate": {
+            "LaunchTemplateSpecification": {
+                "LaunchTemplateId": "lt-53c2425cffa544c23",
+                "LaunchTemplateName": "random-LaunchTemplate",
+                "Version": "2"
+            },
+            "Overrides": [
+                {
+                    "InstanceType": "m5.xlarge"
+                },
+                {
+                    "InstanceType": "m5a.xlarge"
+                },
+            ]
+        }
+    }
 pending_instances:
     description: Number of instances in pending state
     returned: success
@@ -526,6 +605,7 @@
 '''
 
 import time
+import traceback
 
 try:
     import botocore
@@ -537,6 +617,7 @@
 from ansible_collections.amazon.aws.plugins.module_utils.core import AnsibleAWSModule
 from ansible_collections.amazon.aws.plugins.module_utils.core import is_boto3_error_code
 from ansible_collections.amazon.aws.plugins.module_utils.ec2 import AWSRetry
+from ansible_collections.amazon.aws.plugins.module_utils.ec2 import snake_dict_to_camel_dict
 
 ASG_ATTRIBUTES = ('AvailabilityZones', 'DefaultCooldown', 'DesiredCapacity',
                   'HealthCheckGracePeriod', 'HealthCheckType', 'LaunchConfigurationName',
@@ -740,9 +821,7 @@ def get_properties(autoscaling_group):
     properties['termination_policies'] = autoscaling_group.get('TerminationPolicies')
     properties['target_group_arns'] = autoscaling_group.get('TargetGroupARNs')
     properties['vpc_zone_identifier'] = autoscaling_group.get('VPCZoneIdentifier')
-    raw_mixed_instance_object = autoscaling_group.get('MixedInstancesPolicy')
-    if raw_mixed_instance_object:
-        properties['mixed_instances_policy'] = [x['InstanceType'] for x in raw_mixed_instance_object.get('LaunchTemplate').get('Overrides')]
+    properties['mixed_instances_policy'] = autoscaling_group.get('MixedInstancesPolicy')
 
     metrics = autoscaling_group.get('EnabledMetrics')
     if metrics:
@@ -792,6 +871,7 @@ def get_launch_object(connection, ec2_connection):
 
         if mixed_instances_policy:
             instance_types = mixed_instances_policy.get('instance_types', [])
+            instances_distribution = mixed_instances_policy.get('instances_distribution', {})
             policy = {
                 'LaunchTemplate': {
                     'LaunchTemplateSpecification': launch_object['LaunchTemplate']
@@ -802,6 +882,14 @@ def get_launch_object(connection, ec2_connection):
                 for instance_type in instance_types:
                     instance_type_dict = {'InstanceType': instance_type}
                     policy['LaunchTemplate']['Overrides'].append(instance_type_dict)
+            if instances_distribution:
+                instances_distribution_params = dict(
+                    (key.capitalize(), value)  # To Pascal-case.
+                    for key, value
+                    in instances_distribution.items()
+                    if value is not None
+                )
+                policy['InstancesDistribution'] = snake_dict_to_camel_dict(instances_distribution_params)
             launch_object['MixedInstancesPolicy'] = policy
         return launch_object
 
@@ -1661,6 +1749,18 @@ def main():
                     type='list',
                     elements='str'
                 ),
+                instances_distribution=dict(
+                    type='dict',
+                    default=None,
+                    options=dict(
+                        on_demand_allocation_strategy=dict(type='str'),
+                        on_demand_base_capacity=dict(type='int'),
+                        on_demand_percentage_above_base_capacity=dict(type='int'),
+                        spot_allocation_strategy=dict(type='str'),
+                        spot_instance_pools=dict(type='int'),
+                        spot_max_price=dict(type='str'),
+                    )
+                )
             )
         ),
         placement_group=dict(type='str'),

tests/integration/targets/ec2_asg/tasks/main.yml

@@ -629,7 +629,7 @@
       until: status is finished
       retries: 200
       delay: 15
-    
+
     # we need a launch template, otherwise we cannot test the mixed instance policy
     - name: create launch template for autoscaling group to test its mixed instance policy
       ec2_launch_template:
@@ -648,7 +648,7 @@
     - name: update autoscaling group with mixed-instance policy
       ec2_asg:
         name: "{{ resource_prefix }}-asg"
-        launch_template: 
+        launch_template:
           launch_template_name: "{{ resource_prefix }}-lt"
         desired_capacity: 1
         min_size: 1
@@ -659,14 +659,18 @@
           instance_types:
             - t3.micro
             - t3a.micro
+          instances_distribution:
+            on_demand_percentage_above_base_capacity: 0
+            spot_allocation_strategy: capacity-optimized
         wait_for_instances: yes
       register: output
 
     - assert:
         that:
-          - "output.mixed_instances_policy | length == 2"
-          - "output.mixed_instances_policy[0] == 't3.micro'"
-          - "output.mixed_instances_policy[1] == 't3a.micro'"
+          - "output.mixed_instances_policy['LaunchTemplate']['Overrides'][0]['InstanceType'] == 't3.micro'"
+          - "output.mixed_instances_policy['LaunchTemplate']['Overrides'][1]['InstanceType'] == 't3a.micro'"
+          - "output.mixed_instances_policy['InstancesDistribution']['OnDemandPercentageAboveBaseCapacity'] == 0"
+          - "output.mixed_instances_policy['InstancesDistribution']['SpotallocationStrategy'] == 'capacity-optimized'"
 
 # ============================================================