use a const metric for build_info

Signed-off-by: Michael Crosby <michael@thepasture.io>

cmd/containerd/command/main.go

@@ -30,7 +30,7 @@ import (
 	"github.com/containerd/containerd/defaults"
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/log"
-	"github.com/containerd/containerd/metrics"
+	_ "github.com/containerd/containerd/metrics" // import containerd build info
 	"github.com/containerd/containerd/mount"
 	"github.com/containerd/containerd/services/server"
 	srvconfig "github.com/containerd/containerd/services/server/config"
@@ -219,7 +219,6 @@ can be used and modified as necessary as a custom configuration.`
 			serve(ctx, l, server.ServeDebug)
 		}
 		if config.Metrics.Address != "" {
-			metrics.Register()
 			l, err := net.Listen("tcp", config.Metrics.Address)
 			if err != nil {
 				return errors.Wrapf(err, "failed to get listener for metrics endpoint")

metrics/buildinfo.go

@@ -1,50 +0,0 @@
-/*
-   Copyright The containerd 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/containerd/containerd/version"
-	goMetrics "github.com/docker/go-metrics"
-	"github.com/prometheus/client_golang/prometheus"
-)
-
-func newBuildInfoCollector(ns *goMetrics.Namespace) *Collector {
-	return &Collector{
-		ns: ns,
-		m: metric{
-			name: "build_info",
-			help: "Build information on containerd",
-			unit: goMetrics.Total,
-			vt:   prometheus.CounterValue,
-			labels: []string{
-				"version",
-				"revision",
-			},
-			getValues: func() []value {
-				return []value{
-					{
-						l: []string{
-							version.Version,
-							version.Revision,
-						},
-						v: float64(1),
-					},
-				}
-			},
-		},
-	}
-}

metrics/metrics.go

@@ -17,56 +17,13 @@
 package metrics
 
 import (
+	"github.com/containerd/containerd/version"
 	goMetrics "github.com/docker/go-metrics"
-	"github.com/prometheus/client_golang/prometheus"
 )
 
-// Collector provides the ability to collect generic metrics and export
-// them in the prometheus format
-type Collector struct {
-	ns *goMetrics.Namespace
-	m  metric
-}
-
-type metric struct {
-	name   string
-	help   string
-	unit   goMetrics.Unit
-	vt     prometheus.ValueType
-	labels []string
-	// getValues returns the value and labels for the data
-	getValues func() []value
-}
-
-type value struct {
-	v float64
-	l []string
-}
-
-// Describe prometheus metrics
-func (c *Collector) Describe(ch chan<- *prometheus.Desc) {
-	m := c.m
-	ch <- c.ns.NewDesc(m.name, m.help, m.unit, m.labels...)
-}
-
-// Collect prometheus metrics
-func (c *Collector) Collect(ch chan<- prometheus.Metric) {
-	m := c.m
-	for _, v := range m.getValues() {
-		ch <- prometheus.MustNewConstMetric(
-			c.ns.NewDesc(m.name, m.help, m.unit, m.labels...),
-			m.vt,
-			v.v,
-			v.l...,
-		)
-	}
-}
-
-// Register a prometheus namespace for generic metrics
-func Register() {
+func init() {
 	ns := goMetrics.NewNamespace("containerd", "", nil)
-
-	c := newBuildInfoCollector(ns)
-	ns.Add(c)
+	c := ns.NewLabeledCounter("build_info", "containerd build information", "version", "revision")
+	c.WithValues(version.Version, version.Revision).Inc()
 	goMetrics.Register(ns)
 }