# File lib/fog/aws/requests/ecs/start_task.rb, line 43
        def start_task(params={})
          response = Excon::Response.new
          response.status = 200

          unless task_def_id = params.delete('taskDefinition')
            msg = 'ClientException => TaskDefinition cannot be empty.'
            raise Fog::AWS::ECS::Error, msg
          end

          unless instances_id = params.delete('containerInstances')
            msg = 'ClientException => Container instances cannot be empty.'
            raise Fog::AWS::ECS::Error, msg
          end

          begin
            result = describe_task_definition('taskDefinition' => task_def_id).body
            task_def = result["DescribeTaskDefinitionResult"]["taskDefinition"]
            task_def_arn = task_def["taskDefinitionArn"]
          rescue Fog::AWS::ECS::Error => e
            msg = 'ClientException => TaskDefinition not found.'
            raise Fog::AWS::ECS::Error, msg
          end

          if %w(startedBy overrides).any? { |k| params.has_key?(k) }
            Fog::Logger.warning("you used parameters not mocked yet [light_black](#{caller.first})[/]")
            Fog::Mock.not_implemented
          end

          cluster_id = params.delete('cluster') || 'default'
          cluster_arn = nil
          owner_id = Fog::AWS::Mock.owner_id

          if cluster_id.match(/^arn:aws:ecs:.+:\d{1,12}:cluster\/(.+)$/)
            cluster_arn = cluster_id
          else
            cluster_path = "cluster/#{cluster_id}"
            cluster_arn = Fog::AWS::Mock.arn('ecs', owner_id, cluster_path, region)
          end

          task_path = "task/#{UUID.uuid}"
          task_arn = Fog::AWS::Mock.arn('ecs', owner_id, task_path, region)
          instance_path = "container-instance/#{UUID.uuid}"

          instance_id = [*instances_id].first
          if instance_id.match(/^arn:aws:ecs:.+:\d{1,12}:container-instance\/(.+)$/)
            container_instance_arn = instance_id
          else
            instance_path = "container-instance/#{instance_id}"
            container_instance_arn = Fog::AWS::Mock.arn('ecs', owner_id, instance_path, region)
          end

          containers = []
          task_def["containerDefinitions"].each do |c|
            container_path = "container/#{UUID.uuid}"
            containers << {
              'name'         => c['name'],
              'taskArn'      => task_arn,
              'lastStatus'   => 'PENDING',
              'containerArn' => Fog::AWS::Mock.arn('ecs', owner_id, container_path, region)
            }
          end

          task = {
            'clusterArn'           => cluster_arn,
            'desiredStatus'        => 'RUNNING',
            'taskDefinitionArn'    => task_def_arn,
            'lastStatus'           => 'PENDING',
            'taskArn'              => task_arn,
            'containerInstanceArn' => container_instance_arn,
            'containers'           => containers
          }
          self.data[:tasks] << task

          response.body = {
            'StartTaskResult' => {
              'failures' => [],
              'tasks' => [] << task
            },
            'ResponseMetadata' => {
              'RequestId' => Fog::AWS::Mock.request_id
            }
          }
          response
        end