Revert "Revert "move compile time version information (elastic#6050)" (…

…elastic#6087)"

This reverts commit b9fefe1.

dev-tools/set_version

@@ -13,7 +13,8 @@ goversion_template = '''package main
 const appVersion = "{version}"
 '''
 
-goversion_template_libbeat = '''package version
+goversion_template_libbeat = '''// Code generated by dev-tools/set_version
+package version
 
 const defaultBeatVersion = "{version}"
 '''

libbeat/cmd/version.go

@@ -22,8 +22,13 @@ func genVersionCmd(name, beatVersion string) *cobra.Command {
 					return fmt.Errorf("error initializing beat: %s", err)
 				}
 
-				fmt.Printf("%s version %s (%s), libbeat %s\n",
-					beat.Info.Beat, beat.Info.Version, runtime.GOARCH, version.GetDefaultVersion())
+				buildTime := "unknown"
+				if bt := version.BuildTime(); !bt.IsZero() {
+					buildTime = bt.String()
+				}
+				fmt.Printf("%s version %s (%s), libbeat %s [%s built %s]\n",
+					beat.Info.Beat, beat.Info.Version, runtime.GOARCH, version.GetDefaultVersion(),
+					version.Commit(), buildTime)
 				return nil
 			}),
 	}

libbeat/scripts/Makefile

@@ -36,7 +36,8 @@ COVERAGE_TOOL?=${BEAT_GOPATH}/bin/gotestcover
 COVERAGE_TOOL_REPO?=github.com/elastic/beats/vendor/github.com/pierrre/gotestcover
 TESTIFY_TOOL_REPO?=github.com/elastic/beats/vendor/github.com/stretchr/testify/assert
 LIBCOMPOSE_TOOL_REPO?=github.com/docker/libcompose
-GOBUILD_FLAGS?=-i
+NOW=$(shell date -u '+%Y-%m-%dT%H:%M:%SZ')
+GOBUILD_FLAGS?=-i -ldflags "-X github.com/elastic/beats/libbeat/version.buildTime=$(NOW) -X github.com/elastic/beats/libbeat/version.commit=$(COMMIT_ID)"
 GOIMPORTS=goimports
 GOIMPORTS_REPO?=golang.org/x/tools/cmd/goimports
 GOIMPORTS_LOCAL_PREFIX?=github.com/elastic

libbeat/version/helper.go

@@ -1,7 +1,29 @@
 package version
 
+import "time"
+
 // GetDefaultVersion returns the current libbeat version.
 // This method is in a separate file as the version.go file is auto generated
 func GetDefaultVersion() string {
 	return defaultBeatVersion
 }
+
+var (
+	buildTime = "unknown"
+	commit    = "unknown"
+)
+
+// BuildTime exposes the compile-time build time information.
+// It will represent the zero time instant if parsing fails.
+func BuildTime() time.Time {
+	t, err := time.Parse(time.RFC3339, buildTime)
+	if err != nil {
+		return time.Time{}
+	}
+	return t
+}
+
+// Commit exposes the compile-time commit hash.
+func Commit() string {
+	return commit
+}