From 5b6c04976099344b802d30ca285e9788d6aff0f7 Mon Sep 17 00:00:00 2001
From: Julien Pivotto <roidelapluie@o11y.eu>
Date: Sat, 16 Apr 2022 00:53:50 +0200
Subject: [PATCH] go118: Get VCS info from debug.BuildInfo

Signed-off-by: Julien Pivotto <roidelapluie@o11y.eu>
---
 version/info.go         |  6 ++---
 version/info_default.go | 21 +++++++++++++++
 version/info_go118.go   | 58 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 82 insertions(+), 3 deletions(-)
 create mode 100644 version/info_default.go
 create mode 100644 version/info_go118.go

diff --git a/version/info.go b/version/info.go
index 3e2a7ee5..39bcfba6 100644
--- a/version/info.go
+++ b/version/info.go
@@ -46,7 +46,7 @@ func NewCollector(program string) prometheus.Collector {
 			),
 			ConstLabels: prometheus.Labels{
 				"version":   Version,
-				"revision":  Revision,
+				"revision":  getRevision(),
 				"branch":    Branch,
 				"goversion": GoVersion,
 			},
@@ -69,7 +69,7 @@ func Print(program string) string {
 	m := map[string]string{
 		"program":   program,
 		"version":   Version,
-		"revision":  Revision,
+		"revision":  getRevision(),
 		"branch":    Branch,
 		"buildUser": BuildUser,
 		"buildDate": BuildDate,
@@ -87,7 +87,7 @@ func Print(program string) string {
 
 // Info returns version, branch and revision information.
 func Info() string {
-	return fmt.Sprintf("(version=%s, branch=%s, revision=%s)", Version, Branch, Revision)
+	return fmt.Sprintf("(version=%s, branch=%s, revision=%s)", Version, Branch, getRevision())
 }
 
 // BuildContext returns goVersion, buildUser and buildDate information.
diff --git a/version/info_default.go b/version/info_default.go
new file mode 100644
index 00000000..2ab0be00
--- /dev/null
+++ b/version/info_default.go
@@ -0,0 +1,21 @@
+// Copyright 2022 The Prometheus 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.
+
+//go:build !go1.18
+// +build !go1.18
+
+package version
+
+func getRevision() string {
+	return Revision
+}
diff --git a/version/info_go118.go b/version/info_go118.go
new file mode 100644
index 00000000..bed0f499
--- /dev/null
+++ b/version/info_go118.go
@@ -0,0 +1,58 @@
+// Copyright 2022 The Prometheus 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.
+
+//go:build go1.18
+// +build go1.18
+
+package version
+
+import "runtime/debug"
+
+var computedRevision string
+
+func getRevision() string {
+	if Revision != "" {
+		return Revision
+	}
+	return computedRevision
+}
+
+func init() {
+	computedRevision = computeRevision()
+}
+
+func computeRevision() string {
+	var (
+		rev      = "unknown"
+		modified bool
+	)
+
+	buildInfo, ok := debug.ReadBuildInfo()
+	if !ok {
+		return rev
+	}
+	for _, v := range buildInfo.Settings {
+		if v.Key == "vcs.revision" {
+			rev = v.Value
+		}
+		if v.Key == "vcs.modified" {
+			if v.Value == "true" {
+				modified = true
+			}
+		}
+	}
+	if modified {
+		return rev + "-modified"
+	}
+	return rev
+}