server: add prometheus metrics for CRI operations

Signed-off-by: Antonio Murdaca <runcom@redhat.com>

server/metrics/metrics.go

@@ -0,0 +1,70 @@
+package metrics
+
+import (
+	"sync"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const (
+	// CRIOOperationsKey is the key for CRI-O operation metrics.
+	CRIOOperationsKey = "crio_operations"
+	// CRIOOperationsLatencyKey is the key for the operation latency metrics.
+	CRIOOperationsLatencyKey = "crio_operations_latency_microseconds"
+	// CRIOOperationsErrorsKey is the key for the operation error metrics.
+	CRIOOperationsErrorsKey = "crio_operations_errors"
+
+	// TODO(runcom):
+	// timeouts
+
+	subsystem = "container_runtime"
+)
+
+var (
+	// CRIOOperations collects operation counts by operation type.
+	CRIOOperations = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Subsystem: subsystem,
+			Name:      CRIOOperationsKey,
+			Help:      "Cumulative number of CRI-O operations by operation type.",
+		},
+		[]string{"operation_type"},
+	)
+	// CRIOOperationsLatency collects operation latency numbers by operation
+	// type.
+	CRIOOperationsLatency = prometheus.NewSummaryVec(
+		prometheus.SummaryOpts{
+			Subsystem: subsystem,
+			Name:      CRIOOperationsLatencyKey,
+			Help:      "Latency in microseconds of CRI-O operations. Broken down by operation type.",
+		},
+		[]string{"operation_type"},
+	)
+	// CRIOOperationsErrors collects operation errors by operation
+	// type.
+	CRIOOperationsErrors = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Subsystem: subsystem,
+			Name:      CRIOOperationsErrorsKey,
+			Help:      "Cumulative number of CRI-O operation errors by operation type.",
+		},
+		[]string{"operation_type"},
+	)
+)
+
+var registerMetrics sync.Once
+
+// Register all metrics
+func Register() {
+	registerMetrics.Do(func() {
+		prometheus.MustRegister(CRIOOperations)
+		prometheus.MustRegister(CRIOOperationsLatency)
+		prometheus.MustRegister(CRIOOperationsErrors)
+	})
+}
+
+// SinceInMicroseconds gets the time since the specified start in microseconds.
+func SinceInMicroseconds(start time.Time) float64 {
+	return float64(time.Since(start).Nanoseconds() / time.Microsecond.Nanoseconds())
+}