docs(README): update installation instructions for various distributions

systemd/generator.go

@@ -13,11 +13,11 @@ const systemUnitTemplate = `# /etc/systemd/system/{{.ServiceName}}
 
 [Unit]
 Description=Unitdore: {{.Unit.Name}} ({{.Unit.Runtime}})
-After=network.target
+After=network.target{{with .RuntimeService}} {{.}}
+Requires={{.}}{{end}}
 
 [Service]
 Type=simple
-User={{.ServiceUser}}
 ExecStart={{.ExecStart}}
 ExecStop={{.ExecStop}}
 Restart=on-failure
@@ -46,11 +46,11 @@ WantedBy=default.target
 `
 
 type templateData struct {
-	ServiceName string
-	Unit        config.Unit
-	ExecStart   string
-	ExecStop    string
-	ServiceUser string
+	ServiceName    string
+	Unit           config.Unit
+	ExecStart      string
+	ExecStop       string
+	RuntimeService string
 }
 
 // ServiceName returns the systemd service name for a unit, with optional prefix/suffix.
@@ -59,15 +59,15 @@ func ServiceName(u config.Unit, prefix, suffix string) string {
 }
 
 // Generate produces the .service file content for a unit.
-func Generate(u config.Unit, prefix, suffix, serviceUser string) (string, error) {
+func Generate(u config.Unit, prefix, suffix string) (string, error) {
 	execStart, execStop := buildExecCommands(u)
 
 	data := templateData{
-		ServiceName: ServiceName(u, prefix, suffix),
-		Unit:        u,
-		ExecStart:   execStart,
-		ExecStop:    execStop,
-		ServiceUser: serviceUser,
+		ServiceName:    ServiceName(u, prefix, suffix),
+		Unit:           u,
+		ExecStart:      execStart,
+		ExecStop:       execStop,
+		RuntimeService: runtimeService(u.Runtime),
 	}
 
 	tmplStr := systemUnitTemplate
@@ -87,6 +87,15 @@ func Generate(u config.Unit, prefix, suffix, serviceUser string) (string, error)
 	return buf.String(), nil
 }
 
+// runtimeService returns the systemd service name that must be running for the
+// given container runtime, or "" if none is required (e.g. daemonless podman).
+func runtimeService(runtime string) string {
+	if runtime == "docker" {
+		return "docker.service"
+	}
+	return ""
+}
+
 func buildExecCommands(u config.Unit) (start, stop string) {
 	// If a custom command is provided, use it directly
 	if u.Command != "" {