Add wrappers for prometheus.Counter/CounterVec and prometheus.Registry

staging/src/k8s.io/component-base/BUILD

@@ -13,6 +13,7 @@ filegroup(
         "//staging/src/k8s.io/component-base/cli/globalflag:all-srcs",
         "//staging/src/k8s.io/component-base/config:all-srcs",
         "//staging/src/k8s.io/component-base/logs:all-srcs",
+        "//staging/src/k8s.io/component-base/metrics:all-srcs",
     ],
     tags = ["automanaged"],
     visibility = ["//visibility:public"],

staging/src/k8s.io/component-base/metrics/BUILD

@@ -0,0 +1,61 @@
+package(default_visibility = ["//visibility:public"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_library",
+    "go_test",
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "counter.go",
+        "metric.go",
+        "opts.go",
+        "registry.go",
+        "version_parser.go",
+        "wrappers.go",
+    ],
+    importmap = "k8s.io/kubernetes/vendor/k8s.io/component-base/metrics",
+    importpath = "k8s.io/component-base/metrics",
+    deps = [
+        "//staging/src/k8s.io/apimachinery/pkg/version:go_default_library",
+        "//vendor/github.com/blang/semver:go_default_library",
+        "//vendor/github.com/prometheus/client_golang/prometheus:go_default_library",
+        "//vendor/github.com/prometheus/client_model/go:go_default_library",
+        "//vendor/k8s.io/klog:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = [
+        "counter_test.go",
+        "registry_test.go",
+        "version_parser_test.go",
+    ],
+    embed = [":go_default_library"],
+    deps = [
+        "//staging/src/k8s.io/apimachinery/pkg/version:go_default_library",
+        "//vendor/github.com/blang/semver:go_default_library",
+        "//vendor/github.com/prometheus/client_golang/prometheus:go_default_library",
+        "//vendor/github.com/prometheus/common/expfmt:go_default_library",
+        "//vendor/github.com/stretchr/testify/assert:go_default_library",
+    ],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [
+        ":package-srcs",
+        "//staging/src/k8s.io/component-base/metrics/legacyregistry:all-srcs",
+    ],
+    tags = ["automanaged"],
+)

staging/src/k8s.io/component-base/metrics/counter.go

@@ -0,0 +1,145 @@
+/*
+Copyright 2019 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package metrics
+
+import (
+	"github.com/blang/semver"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+// Counter is our internal representation for our wrapping struct around prometheus
+// counters. Counter implements both KubeCollector and CounterMetric.
+type Counter struct {
+	CounterMetric
+	*CounterOpts
+	lazyMetric
+	selfCollector
+}
+
+// NewCounter returns an object which satisfies the KubeCollector and CounterMetric interfaces.
+// However, the object returned will not measure anything unless the collector is first
+// registered, since the metric is lazily instantiated.
+func NewCounter(opts *CounterOpts) *Counter {
+	// todo: handle defaulting better
+	if opts.StabilityLevel == "" {
+		opts.StabilityLevel = ALPHA
+	}
+	kc := &Counter{
+		CounterOpts: opts,
+		lazyMetric:  lazyMetric{},
+	}
+	kc.setPrometheusCounter(noop)
+	kc.lazyInit(kc)
+	return kc
+}
+
+// setPrometheusCounter sets the underlying CounterMetric object, i.e. the thing that does the measurement.
+func (c *Counter) setPrometheusCounter(counter prometheus.Counter) {
+	c.CounterMetric = counter
+	c.initSelfCollection(counter)
+}
+
+// DeprecatedVersion returns a pointer to the Version or nil
+func (c *Counter) DeprecatedVersion() *semver.Version {
+	return c.CounterOpts.DeprecatedVersion
+}
+
+// initializeMetric invocation creates the actual underlying Counter. Until this method is called
+// the underlying counter is a no-op.
+func (c *Counter) initializeMetric() {
+	c.CounterOpts.annotateStabilityLevel()
+	// this actually creates the underlying prometheus counter.
+	c.setPrometheusCounter(prometheus.NewCounter(c.CounterOpts.toPromCounterOpts()))
+}
+
+// initializeDeprecatedMetric invocation creates the actual (but deprecated) Counter. Until this method
+// is called the underlying counter is a no-op.
+func (c *Counter) initializeDeprecatedMetric() {
+	c.CounterOpts.markDeprecated()
+	c.initializeMetric()
+}
+
+// CounterVec is the internal representation of our wrapping struct around prometheus
+// counterVecs. CounterVec implements both KubeCollector and CounterVecMetric.
+type CounterVec struct {
+	*prometheus.CounterVec
+	*CounterOpts
+	lazyMetric
+	originalLabels []string
+}
+
+// NewCounterVec returns an object which satisfies the KubeCollector and CounterVecMetric interfaces.
+// However, the object returned will not measure anything unless the collector is first
+// registered, since the metric is lazily instantiated.
+func NewCounterVec(opts *CounterOpts, labels []string) *CounterVec {
+	cv := &CounterVec{
+		CounterVec:     noopCounterVec,
+		CounterOpts:    opts,
+		originalLabels: labels,
+		lazyMetric:     lazyMetric{},
+	}
+	cv.lazyInit(cv)
+	return cv
+}
+
+// DeprecatedVersion returns a pointer to the Version or nil
+func (v *CounterVec) DeprecatedVersion() *semver.Version {
+	return v.CounterOpts.DeprecatedVersion
+}
+
+// initializeMetric invocation creates the actual underlying CounterVec. Until this method is called
+// the underlying counterVec is a no-op.
+func (v *CounterVec) initializeMetric() {
+	v.CounterVec = prometheus.NewCounterVec(v.CounterOpts.toPromCounterOpts(), v.originalLabels)
+}
+
+// initializeDeprecatedMetric invocation creates the actual (but deprecated) CounterVec. Until this method is called
+// the underlying counterVec is a no-op.
+func (v *CounterVec) initializeDeprecatedMetric() {
+	v.CounterOpts.markDeprecated()
+	v.initializeMetric()
+}
+
+// Default Prometheus behavior actually results in the creation of a new metric
+// if a metric with the unique label values is not found in the underlying stored metricMap.
+// This means  that if this function is called but the underlying metric is not registered
+// (which means it will never be exposed externally nor consumed), the metric will exist in memory
+// for perpetuity (i.e. throughout application lifecycle).
+//
+// For reference: https://github.com/prometheus/client_golang/blob/v0.9.2/prometheus/counter.go#L179-L197
+
+// WithLabelValues returns the Counter for the given slice of label
+// values (same order as the VariableLabels in Desc). If that combination of
+// label values is accessed for the first time, a new Counter is created IFF the counterVec
+// has been registered to a metrics registry.
+func (v *CounterVec) WithLabelValues(lvs ...string) CounterMetric {
+	if !v.IsCreated() {
+		return noop // return no-op counter
+	}
+	return v.CounterVec.WithLabelValues(lvs...)
+}
+
+// With returns the Counter for the given Labels map (the label names
+// must match those of the VariableLabels in Desc). If that label map is
+// accessed for the first time, a new Counter is created IFF the counterVec has
+// been registered to a metrics registry.
+func (v *CounterVec) With(labels prometheus.Labels) CounterMetric {
+	if !v.IsCreated() {
+		return noop // return no-op counter
+	}
+	return v.CounterVec.With(labels)
+}