[setup] Write binary checksum to service unit

setup/setup.go

@@ -80,6 +80,9 @@ var configDir = "/etc"
 // unitComment is comment for service unit
 var unitComment = "# Unit generated by ek.go/setup"
 
+// checksum is current binary checksum
+var checksum string
+
 // ////////////////////////////////////////////////////////////////////////////////// //
 
 // Install installs or reinstalls application on the system
@@ -142,14 +145,25 @@ func (b *binaryInfo) ServiceUnitPath() string {
 // IsBinInstalled returns true if current binary already installed
 func (b *binaryInfo) IsBinInstalled() bool {
 	return fsutil.IsExist(b.BinInstallPath()) &&
-		hash.FileHash(b.File) == hash.FileHash(b.BinInstallPath())
+		b.Checksum() == hash.FileHash(b.BinInstallPath())
 }
 
 // IsServiceInstalled returns true if service unit already installed
 func (b *binaryInfo) IsServiceInstalled() bool {
 	return fsutil.IsExist(b.ServiceUnitPath())
 }
 
+// Checksum returns checksum of current binary
+func (b *binaryInfo) Checksum() string {
+	if checksum != "" {
+		return checksum
+	}
+
+	checksum = hash.FileHash(b.File)
+
+	return checksum
+}
+
 // ////////////////////////////////////////////////////////////////////////////////// //
 
 // getBinary returns basic info about current binary
@@ -367,7 +381,12 @@ func createServiceFile(app App, bin binaryInfo) error {
 func generateServiceUnit(app App, bin binaryInfo) []byte {
 	var buf bytes.Buffer
 
-	buf.WriteString(unitComment + "\n\n")
+	buf.WriteString(fmt.Sprintf(
+		"%s (%s)\n\n",
+		unitComment,
+		strutil.Head(bin.Checksum(), 7),
+	))
+
 	buf.WriteString("[Unit]\n")
 	buf.WriteString(fmt.Sprintf("Description=%s\n", strutil.Q(app.Name, bin.Name)))