From 87ba3a16a87097fb4e6ad84d33fd5e18c53bbcce Mon Sep 17 00:00:00 2001
From: Phil Porada <philporada@gmail.com>
Date: Mon, 20 May 2024 11:44:22 -0400
Subject: [PATCH] Add build flags

---
 .github/workflows/release.yml |  2 +-
 unbound_exporter.go           |  7 +++-
 util/buildVars.go             | 61 +++++++++++++++++++++++++++++++++++
 3 files changed, 68 insertions(+), 2 deletions(-)
 create mode 100644 util/buildVars.go

diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index d7c3822..aad52c2 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -23,7 +23,7 @@ jobs:
           persist-credentials: false
 
       - name: build binary
-        run: go build
+        run: go build -ldflags "-X github.com/letsencrypt/unbound_exporter/util.BuildID=$(git rev-parse --short HEAD) -X github.com/letsencrypt/unbound_exporter/util.BuildBranch=$(git rev-parse --abbrev-ref HEAD) -X github.com/letsencrypt/unbound_exporter/util.BuildTime=$(date +%F-%T -u)"
 
       - name: install nfpm
         run: go install github.com/goreleaser/nfpm/v2/cmd/nfpm@v2.15.1
diff --git a/unbound_exporter.go b/unbound_exporter.go
index 291bb00..3929e62 100644
--- a/unbound_exporter.go
+++ b/unbound_exporter.go
@@ -25,12 +25,14 @@ import (
 	"net/url"
 	"os"
 	"regexp"
+	"runtime"
 	"strconv"
 	"strings"
 
 	"sort"
 
 	"github.com/go-kit/log/level"
+	"github.com/letsencrypt/unbound_exporter/util"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/prometheus/common/promlog"
@@ -548,7 +550,10 @@ func main() {
 	)
 	flag.Parse()
 
-	_ = level.Info(log).Log("Starting unbound_exporter")
+	_ = level.Info(log).Log(
+		"msg", "Starting unbound_exporter",
+		"version", fmt.Sprintf("(version=%s, branch=%s, revision=%s)", runtime.Version(), util.GetBuildBranch(), util.GetBuildID()),
+	)
 	exporter, err := NewUnboundExporter(*unboundHost, *unboundCa, *unboundCert, *unboundKey)
 	if err != nil {
 		panic(err)
diff --git a/util/buildVars.go b/util/buildVars.go
new file mode 100644
index 0000000..4d9b259
--- /dev/null
+++ b/util/buildVars.go
@@ -0,0 +1,61 @@
+package util
+
+import (
+	"expvar"
+)
+
+const Unspecified = "Unspecified"
+
+// BuildID is set by the compiler (using -ldflags "-X util.BuildID $(git rev-parse --short HEAD)")
+// and is used by GetBuildID
+var BuildID string
+
+// BuildHost is set by the compiler and is used by GetBuildHost
+var BuildHost string
+
+// BuildTime is set by the compiler and is used by GetBuildTime
+var BuildTime string
+
+// BuildBranch is set by the compiler and is used by GetBuildBranch
+var BuildBranch string
+
+func init() {
+	expvar.NewString("BuildID").Set(BuildID)
+	expvar.NewString("BuildTime").Set(BuildTime)
+}
+
+// GetBuildID identifies what build is running.
+func GetBuildID() (retID string) {
+	retID = BuildID
+	if retID == "" {
+		retID = Unspecified
+	}
+	return
+}
+
+// GetBuildTime identifies when this build was made
+func GetBuildTime() (retID string) {
+	retID = BuildTime
+	if retID == "" {
+		retID = Unspecified
+	}
+	return
+}
+
+// GetBuildHost identifies the building host
+func GetBuildHost() (retID string) {
+	retID = BuildHost
+	if retID == "" {
+		retID = Unspecified
+	}
+	return
+}
+
+// GetBuildBranch identifies the building host
+func GetBuildBranch() (retID string) {
+	retID = BuildBranch
+	if retID == "" {
+		retID = Unspecified
+	}
+	return
+}