const (
    // DockerOperationsKey is the key for docker operation metrics.
    DockerOperationsKey = "docker_operations_total"
    // DockerOperationsLatencyKey is the key for the operation latency metrics.
    DockerOperationsLatencyKey = "docker_operations_duration_seconds"
    // DockerOperationsErrorsKey is the key for the operation error metrics.
    DockerOperationsErrorsKey = "docker_operations_errors_total"
    // DockerOperationsTimeoutKey is the key for the operation timeout metrics.
    DockerOperationsTimeoutKey = "docker_operations_timeout_total"
)

var (
    // DockerOperationsLatency collects operation latency numbers by operation
    // type.
    DockerOperationsLatency = metrics.NewHistogramVec(
        &metrics.HistogramOpts{
            Subsystem:      kubeletSubsystem,
            Name:           DockerOperationsLatencyKey,
            Help:           "Latency in seconds of Docker operations. Broken down by operation type.",
            Buckets:        metrics.DefBuckets,
            StabilityLevel: metrics.ALPHA,
        },
        []string{"operation_type"},
    )
    // DockerOperations collects operation counts by operation type.
    DockerOperations = metrics.NewCounterVec(
        &metrics.CounterOpts{
            Subsystem:      kubeletSubsystem,
            Name:           DockerOperationsKey,
            Help:           "Cumulative number of Docker operations by operation type.",
            StabilityLevel: metrics.ALPHA,
        },
        []string{"operation_type"},
    )
    // DockerOperationsErrors collects operation errors by operation
    // type.
    DockerOperationsErrors = metrics.NewCounterVec(
        &metrics.CounterOpts{
            Subsystem:      kubeletSubsystem,
            Name:           DockerOperationsErrorsKey,
            Help:           "Cumulative number of Docker operation errors by operation type.",
            StabilityLevel: metrics.ALPHA,
        },
        []string{"operation_type"},
    )
    // DockerOperationsTimeout collects operation timeouts by operation type.
    DockerOperationsTimeout = metrics.NewCounterVec(
        &metrics.CounterOpts{
            Subsystem:      kubeletSubsystem,
            Name:           DockerOperationsTimeoutKey,
            Help:           "Cumulative number of Docker operation timeout by operation type.",
            StabilityLevel: metrics.ALPHA,
        },
        []string{"operation_type"},
    )
)