the flag config.filter-label not work

[denghejun]

{
        name      = "prometheus-ecs-discovery"
        command   = ["-config.write-to=/output/ecs_file_sd.yml -config.filter-label=ENV_TAG=mydev"]
        cpu       = 0
        essential = true
        image     = "tkgregory/prometheus-ecs-discovery:latest"
        logConfiguration = {
          logDriver = "awslogs"
          options = {
            awslogs-group         = "/ecs/eve-recommendation-service"
            awslogs-region        = "eu-west-1"
            awslogs-stream-prefix = "ecs"
          }
        }
        environment = [{
          name  = "AWS_REGION"
          value = "eu-west-1"
        }]

        memoryReservation = 1024
        mountPoints = [
          {
            sourceVolume : "config",
            containerPath : "/output"
          }
        ]
        portMappings = []
        volumesFrom  = []
      }

 dockerLabels = {
          PROMETHEUS_EXPORTER_PATH = "/metrics"
          PROMETHEUS_EXPORTER_PORT = "2112"
          ENV_TAG                  = "mydev"
        }