Pass frps.ini file via an env var (#5)

* Introduce FRPS_INI_PATH env var

* Add sample systemd unit files

Earthfile

@@ -8,6 +8,7 @@ validate-pr:
   RUN go mod download
   COPY . .
   RUN CGO_ENABLED=0 GOOS=linux go build -o ./build/frp-port-keeper ./main.go
+  SAVE ARTIFACT build /build AS LOCAL ./build
 
 multi-build:
   ARG --required RELEASE_VERSION

README.md

@@ -113,11 +113,17 @@ It is possible that the plugin works for older version even though it has not be
  5. Run the frp server.
  6. Profit.
 
+### Usage as Systemd service
+You may want to delegate the control of frp-port-keeper to Systemd just like
+you probably did with the frps service. There are sample Systemd unit files in
+the `systemd` folder. Just tweak them to your liking and copy to the `/etc/systemd/system/`
+folder.
+
+
 ## TODO
 - [ ] Pass `allow_ports` param via cli  
 - [ ] Add unit tests  
 - [ ] Add proper error handling in case if payload is not as expected  
 - [ ] Cross compile for other platforms (currently supports only amd64)  
 - [ ] Refactor by improving modules/folder structure following golang best practices  
-- [ ] Add systemd files and instructions to run the plugin as systemd service
-
+- [ ] Add systemd files and instructions to run the plugin as systemd service  

main.go

@@ -58,12 +58,22 @@ func UnmarshalServerConfFromIni(source interface{}) (ServerConf, error) {
 func init() {
 	fmt.Println("🐔 Initializing the plugin...")
 
+	// Get the frps.ini file path from the environment variable
+	frpsIniPath := os.Getenv("FRPS_INI_PATH")
+
+	// If the environment variable is empty or not set
+	if frpsIniPath == "" {
+		// Use the default directory
+		frpsIniPath = "./frps.ini"
+	}
+
 	// Check if frps.ini exists
-	if _, err := os.Stat("./frps.ini"); os.IsNotExist(err) {
-		panic("frps.ini does not exist; move the frp-port-keeper binary to the same folder where the frps.ini located and call frp-port-keeper from there.")
+	if _, err := os.Stat(frpsIniPath); os.IsNotExist(err) {
+		panicMsg, _ := fmt.Printf("frps.ini does not exist at path %s; move the frp-port-keeper binary to the same folder where the frps.ini located and call frp-port-keeper from there.", frpsIniPath)
+		panic(panicMsg)
 	}
 
-	var commonSection, err = UnmarshalServerConfFromIni("./frps.ini")
+	var commonSection, err = UnmarshalServerConfFromIni(frpsIniPath)
 	if err != nil {
 		fmt.Println("got error: ", err)
 	}

systemd/frp-port-keeper.service

@@ -0,0 +1,16 @@
+[Unit]
+Description=frp-port-keeper service
+Documentation=https://github.com/librepod/frp-port-keeper
+After=network.target nss-lookup.target
+
+[Service]
+User=root
+Group=root
+WorkingDirectory=/etc/frp
+Environment="FRPS_INI_PATH=/etc/frp/frps.ini"
+ExecStart=/etc/frp/frp-port-keeper
+Restart=on-failure
+RestartPreventExitStatus=23
+
+[Install]
+WantedBy=multi-user.target

systemd/frp-port-keeper@.service

@@ -0,0 +1,16 @@
+[Unit]
+Description=frp-port-keeper service
+Documentation=https://github.com/librepod/frp-port-keeper
+After=network.target nss-lookup.target
+
+[Service]
+User=root
+Group=root
+WorkingDirectory=/etc/frp
+Environment="FRPS_INI_PATH=/etc/frp/frps.ini"
+ExecStart=/etc/frp/frp-port-keeper
+Restart=on-failure
+RestartPreventExitStatus=23
+
+[Install]
+WantedBy=multi-user.target