def lambda_handler()

in BackendServices/functions/scaler.py [0:0]

• 34 lines of code
• 13 McCabe index (conditional complexity)

def lambda_handler(event, context):

    print("Running scheduled Lambda function to start new game server tasks when necessary")

    # Get the resources from ECS and Task CLoudFormation Stacks from environment variables
    ecs_cluster_name = os.environ['ECS_CLUSTER_NAME'] 
    ecs_task_definition = ""

    cloudformation = boto3.client("cloudformation")
    # Get the Task to deploy (as this changes dynamically)
    stack = cloudformation.describe_stacks(StackName="fleetiq-game-servers-task-definition")["Stacks"][0]
    for output in stack["Outputs"]:
        print('%s=%s (%s)' % (output["OutputKey"], output["OutputValue"], output["Description"]))
        if output["OutputKey"] == "TaskDefinition":
            ecs_task_definition = output["OutputValue"]

    # Track start time
    start_time = time.time()

    ### Run the scaler up to 60 seconds (next one will be triggered after 1 minute)
    while (time.time() - start_time) < 59.0:

        try:
            # 1. Check Fleet CPU and Memory capacity
            total_cpu, total_memory = get_available_memory_and_cpu(ecs_cluster_name)
            print("Total CPU: " + str(total_cpu) + " Total Memory: " + str(total_memory))

            # 2. Check how many game server Tasks we can start
            max_tasks_based_on_cpu = int(total_cpu / cpu_per_task)
            max_tasks_based_on_memory = int(total_memory / memory_per_task)

            print("Total to start cpu: " + str(max_tasks_based_on_cpu) + " total to start mem: " + str(max_tasks_based_on_memory))

            # Start the lowest value of cpu and memory bound and max of 10 per round
            total_to_start = min(max_tasks_based_on_cpu, max_tasks_based_on_memory, 10)

            print("Will start: " + str(total_to_start))

            # Spin up the missing servers
            if total_to_start > 0:
                # Start a game server ECS Task for each missing game serve
                    client = boto3.client('ecs')
                    response = client.run_task(
                        cluster=ecs_cluster_name,
                        launchType = 'EC2',
                        taskDefinition=ecs_task_definition,
                        count = total_to_start
                    )
        except Exception as e:
            print("Exception occured in starting Tasks")
            print(e)
        # Wait for next round unless this was the last on this minute
        if time.time() - start_time < 59.0:
            print("Wait 1 second before next round")
            time.sleep(1.0)