ecs_update

#!/usr/bin/python2
# This file is part of Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.

DOCUMENTATION = '''
---
module: ecs_service
short_description: Update service on ECS cluster
description:
    - Usage Amazon ECS API to update a service definition.
version_added: ""
options:
  cluster:
    description:
      - The name of the ECS cluster to operate on
    required: true
    default: null
    aliases: []
  service:
    description:
      - The name of the ECS service to update
    required: true
    default: null
    aliases: []
  region:
    description:
      - The AWS region to operate in
    required: false
    default: region specified in boto configuration
    aliases: []
  desired_count:
    description:
      - The desired number of service instances to run
    required: true
    default: null
    aliases: []
  wait:
    description:
      - Wait for the call to complete, or exit after call has been submitted
    default: false
    aliases: []
'''

EXAMPLES = '''
# Update desired count of `service1` on `primary-cluster` to 2
- ecs_service:
    cluster: primary-cluster
    service: service1
    region: us-east-1
    desired_count: 2


# Stop all running instances of the service and wait for completion
- ecs_service:
    cluster: primary-cluster
    service: service1
    desired_count: 0
    region: us-east-1
    wait: true
'''

import json

HAS_BOTO3 = True
try:
    import boto3
except ImportError:
    HAS_BOTO3 = False


class ECSManager:
    def __init__(self, module):
        self.module = module
        self.cluster = module.params.get('cluster')
        self.service = module.params.get('service')
        self.desired_count = module.params.get('desired_count')
        self.region = module.params.get('region')
        self.wait = module.params.get('wait')

    def run(self):
        ecs = None
        if self.region:
            ecs = boto3.client('ecs', region_name=self.region)
        else:
            ecs = boto3.client('ecs')

        service = ecs.describe_services(
            cluster=self.cluster,
            services=[self.service]
        )['services'][0]

        if self.desired_count == service['runningCount']:
            self.module.exit_json(
                msg='desired_count == running_count (%s == %s)' % (service['desiredCount'], service['runningCount']),
                changed=False
            )
        else:
            changed = True

        ecs.update_service(
            cluster=self.cluster,
            service=self.service,
            desiredCount=self.desired_count
        )

        if self.wait:
            waiter = ecs.get_waiter('services_stable')
            waiter.wait(cluster=self.cluster, services=[self.service])

        self.module.exit_json(
            msg="Successfully changed %s instance count on %s to %s" % (
                self.service, self.cluster, self.desired_count
            ),
            changed=True,
            success=True,
            output="%s instance count on %s changed from %s to %s" % (
                self.service,
                self.cluster,
                service['runningCount'],
                self.desired_count
            )
        )

        # Check and Note any existing image to compare to
        self.module.exit_json(
            msg=msg,
            changed=changed,
            success=True,
            output=output
        )


def main():
    argument_spec = dict(
        cluster=dict(type='str'),
        service=dict(type='str'),
        desired_count=dict(type='int'),
        region=dict(default=None, type='str'),
        wait=dict(default=False, type='bool')
    )

    module = AnsibleModule(argument_spec=argument_spec)

    if not HAS_BOTO3:
        module.fail_json(
            msg='The Docker python client is required for this module'
        )

    manager = ECSManager(module)
    manager.run()


from ansible.module_utils.basic import *

main()

argument_spec = dict(
   cluster=dict(type='str'),
   service=dict(type='str'),
   desired_count=dict(type='int'),
   region=dict(default=None, type='str'),
   wait=dict(default=False, type='bool')

)

More readable?

argument_spec = {
    'cluster': { 'type': 'str' },
    'service': { 'type': 'str' },
    ...
}