Add version-info to tablet tags in the topo

Signed-off-by: Andrew Mason <[email protected]>

go/vt/servenv/buildinfo.go

@@ -56,6 +56,24 @@ type versionInfo struct {
 	version            string
 }
 
+// ToStringMap returns the version info as a map[string]string, allowing version
+// info to be used in things like arbitrary string-tag maps (e.g. tablet tags
+// in the topo).
+func (v *versionInfo) ToStringMap() map[string]string {
+	return map[string]string{
+		"build_host":           v.buildHost,
+		"build_user":           v.buildUser,
+		"build_time":           v.buildTimePretty,
+		"build_git_rev":        v.buildGitRev,
+		"build_git_branch":     v.buildGitBranch,
+		"jenkins_build_number": fmt.Sprintf("%d", v.jenkinsBuildNumber),
+		"go_version":           v.goVersion,
+		"goos":                 v.goOS,
+		"goarch":               v.goArch,
+		"version":              v.version,
+	}
+}
+
 func (v *versionInfo) Print() {
 	fmt.Println(v)
 }

go/vt/vttablet/tabletmanager/tm_init.go

@@ -237,10 +237,28 @@ func BuildTabletFromInput(alias *topodatapb.TabletAlias, port, grpcPort int32) (
 		KeyRange:       keyRange,
 		Type:           tabletType,
 		DbNameOverride: *initDbNameOverride,
-		Tags:           initTags,
+		Tags:           mergeTags(servenv.AppVersion.ToStringMap(), initTags),
 	}, nil
 }
 
+func mergeTags(a, b map[string]string) map[string]string {
+	maxCap := len(a)
+	if x := len(b); x > maxCap {
+		maxCap = x
+	}
+
+	result := make(map[string]string, maxCap)
+	for k, v := range a {
+		result[k] = v
+	}
+
+	for k, v := range b {
+		result[k] = v
+	}
+
+	return result
+}
+
 // Start starts the TabletManager.
 func (tm *TabletManager) Start(tablet *topodatapb.Tablet, healthCheckInterval time.Duration) error {
 	tm.DBConfigs.DBName = topoproto.TabletDbName(tablet)