internal/contour: Add contour version to metrics

Dockerfile

@@ -8,7 +8,18 @@ RUN go mod download
 COPY cmd cmd
 COPY internal internal
 COPY apis apis
-RUN CGO_ENABLED=0 GOOS=linux GOFLAGS=-ldflags=-w go build -o /go/bin/contour -ldflags=-s -v github.com/projectcontour/contour/cmd/contour
+COPY Makefile Makefile
+
+ARG BUILD_BRANCH
+ARG BUILD_SHA
+ARG BUILD_VERSION
+
+RUN make install \
+	    CGO_ENABLED=0 \
+	    GOOS=linux \
+	    BUILD_VERSION=${BUILD_VERSION} \
+	    BUILD_SHA=${BUILD_SHA} \
+	    BUILD_BRANCH=${BUILD_BRANCH}
 
 FROM scratch AS final
 COPY --from=build /go/bin/contour /bin/contour

Makefile

@@ -28,7 +28,20 @@ VERSION ?= $(GIT_REF)
 # set outside this Makefile, as a safety valve.
 LATEST_VERSION ?= NOLATEST
 
+# Sets the current Git sha
+BUILD_SHA = $(shell git rev-parse --verify HEAD)
+# Sets the current branch
+BUILD_BRANCH = $(shell git branch --show-current)
+# Sets the current tagged git version
+BUILD_VERSION = $(VERSION)
+
+GO_BUILD_VARS = \
+	github.com/projectcontour/contour/internal/build.Version=${BUILD_VERSION} \
+	github.com/projectcontour/contour/internal/build.Sha=${BUILD_SHA} \
+	github.com/projectcontour/contour/internal/build.Branch=${BUILD_BRANCH}
+
 GO_TAGS := -tags "oidc gcp"
+GO_LDFLAGS := -s $(patsubst %,-X %, $(GO_BUILD_VARS))
 
 export GO111MODULE=on
 
@@ -39,7 +52,7 @@ check: install check-test check-test-race ## Install and run tests
 checkall: check lint check-generate
 
 install: ## Build and install the contour binary
-	go install -mod=readonly -v $(GO_TAGS) $(MODULE)/cmd/contour
+	go install -mod=readonly -v -ldflags="$(GO_LDFLAGS)" $(GO_TAGS) $(MODULE)/cmd/contour
 
 race:
 	go install -mod=readonly -v -race $(GO_TAGS) $(MODULE)/cmd/contour
@@ -48,7 +61,7 @@ download: ## Download Go modules
 	go mod download
 
 container: ## Build the Contour container image
-	docker build . -t $(IMAGE):$(VERSION)
+	docker build --build-arg BUILD_VERSION=$(BUILD_VERSION) --build-arg BUILD_BRANCH=$(BUILD_BRANCH) --build-arg BUILD_SHA=$(BUILD_SHA) . -t $(IMAGE):$(VERSION)
 
 push: ## Push the Contour container image to the Docker registry
 push: container

internal/build/version.go

@@ -0,0 +1,23 @@
+// Copyright © 2020 VMware
+// 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 build
+
+// Branch allows for a queryable branch name set at build time.
+var Branch string
+
+// Sha allows for a queryable git sha set at build time.
+var Sha string
+
+// Version allows for a queryable version set at build time.
+var Version string

internal/metrics/metrics.go

@@ -21,13 +21,15 @@ import (
 
 	"k8s.io/client-go/kubernetes"
 
+	"github.com/projectcontour/contour/internal/build"
 	"github.com/projectcontour/contour/internal/httpsvc"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
 // Metrics provide Prometheus metrics for the app
 type Metrics struct {
+	buildInfoGauge             *prometheus.GaugeVec
 	ingressRouteTotalGauge     *prometheus.GaugeVec
 	ingressRouteRootTotalGauge *prometheus.GaugeVec
 	ingressRouteInvalidGauge   *prometheus.GaugeVec
@@ -64,6 +66,7 @@ type Meta struct {
 }
 
 const (
+	BuildInfoGauge             = "contour_build_info"
 	IngressRouteTotalGauge     = "contour_ingressroute_total"
 	IngressRouteRootTotalGauge = "contour_ingressroute_root_total"
 	IngressRouteInvalidGauge   = "contour_ingressroute_invalid_total"
@@ -89,6 +92,13 @@ const (
 // to regenerate the metrics documentation.
 func NewMetrics(registry *prometheus.Registry) *Metrics {
 	m := Metrics{
+		buildInfoGauge: prometheus.NewGaugeVec(
+			prometheus.GaugeOpts{
+				Name: BuildInfoGauge,
+				Help: "Build information for Contour. Labels include the branch and git SHA that Contour was built from, and the Contour version.",
+			},
+			[]string{"branch", "revision", "version"},
+		),
 		ingressRouteMetricCache: &RouteMetric{},
 		proxyMetricCache:        &RouteMetric{},
 		ingressRouteTotalGauge: prometheus.NewGaugeVec(
@@ -181,13 +191,15 @@ func NewMetrics(registry *prometheus.Registry) *Metrics {
 			[]string{"op", "kind"},
 		),
 	}
+	m.buildInfoGauge.WithLabelValues(build.Branch, build.Sha, build.Version).Set(1)
 	m.register(registry)
 	return &m
 }
 
 // register registers the Metrics with the supplied registry.
 func (m *Metrics) register(registry *prometheus.Registry) {
 	registry.MustRegister(
+		m.buildInfoGauge,
 		m.ingressRouteTotalGauge,
 		m.ingressRouteRootTotalGauge,
 		m.ingressRouteInvalidGauge,

site/_metrics/contour_build_info.md

@@ -0,0 +1,7 @@
+---
+name: 'contour_build_info'
+type: '[GAUGE](https://prometheus.io/docs/concepts/metric_types/#gauge)'
+labels: 'branch, revision, version'
+---
+
+Build information for Contour. Labels include the branch and git SHA that Contour was built from, and the Contour version.