Add metric exposing build version&revision

Signed-off-by: Nicolas Chariglione <nicolas.chariglione@gmail.com>

cmd/containerd/command/main.go

@@ -30,6 +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/mount"
 	"github.com/containerd/containerd/services/server"
 	srvconfig "github.com/containerd/containerd/services/server/config"
@@ -218,6 +219,7 @@ 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

@@ -0,0 +1,50 @@
+/*
+   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

@@ -0,0 +1,72 @@
+/*
+   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 (
+	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() {
+	ns := goMetrics.NewNamespace("containerd", "", nil)
+
+	c := newBuildInfoCollector(ns)
+	ns.Add(c)
+	goMetrics.Register(ns)
+}