Systemd/dep (#165)

* support the dependency config for linux systemd

* remote the binary file incorrectly added

example/logging/main.go

@@ -67,6 +67,9 @@ func main() {
 		Name:        "GoServiceExampleLogging",
 		DisplayName: "Go Service Example for Logging",
 		Description: "This is an example Go service that outputs log messages.",
+		Dependencies: []string{
+			"Requires=network.target",
+			"After=network-online.target syslog.target"},
 	}
 
 	prg := &program{}

service.go

@@ -111,7 +111,13 @@ type Config struct {
 	Executable string
 
 	// Array of service dependencies.
-	// Not yet implemented on Linux or OS X.
+	// Not yet fully implemented on Linux or OS X:
+	//  1. Support linux-systemd dependencies, just put each full line as the
+	//     element of the string array, such as
+	//     "After=network.target syslog.target"
+	//     "Requires=syslog.target"
+	//     Note, such lines will be directly appended into the [Unit] of
+	//     the generated service config file, will not check their correctness.
 	Dependencies []string
 
 	// The following fields are not supported on Windows.

service_systemd_linux.go

@@ -228,6 +228,9 @@ func (s *systemd) Restart() error {
 const systemdScript = `[Unit]
 Description={{.Description}}
 ConditionFileIsExecutable={{.Path|cmdEscape}}
+{{range .Dependencies}}
+{{.}}
+{{end}}
 
 [Service]
 StartLimitInterval=5