use environment variables for dynamic configuration

README.md

@@ -4,6 +4,10 @@ Features:
 * Authenticates email accounts against the SQLite database used by Hostux panel
 * Updates "last accessed" on a successful authentication
 
+Configuration through environment variables:
+* `HOSTUX_EMAIL_DATABASE_SQLITE`: required, path to the database containing the email addresses
+* `HOSTUX_EMAIL_CHECKPW_LOGFILE`: if set, logs are written to the path indicated
+
 ## Testing
 
 ### Maddy

main.go

@@ -17,26 +17,25 @@ import (
  *  2: other error
  */
 func main() {
-	// Checks usage
+	// Opens the SQLite database
-	if len(os.Args) != 2 {
+	dbFile, dbFileSet := os.LookupEnv("HOSTUX_EMAIL_DATABASE_SQLITE")
-		fmt.Println("Usage: hostux_check_credentials [database.sqlite]")
+	if !dbFileSet {
+		logMessage("Environment variable HOSTUX_EMAIL_DATABASE_SQLITE must be set.")
 		os.Exit(2)
 	}
 
-	// Opens the SQLite database
-	dbFile := os.Args[1]
 	db, err := sql.Open("sqlite3", dbFile)
 	if err != nil {
-		fmt.Println("Error opening database:", err)
+		logMessage("Error opening database:", err)
 		os.Exit(2)
 	}
 	defer db.Close()
 
 	// Reads stdin input (email address, password, each ends with \n)
 	var emailAddress, password string
-	fmt.Println("Enter email address:")
+	logMessage("Enter email address:")
 	fmt.Scanln(&emailAddress)
-	fmt.Println("Enter password:")
+	logMessage("Enter password:")
 	fmt.Scanln(&password)
 
 	// Finds database records
@@ -44,7 +43,7 @@ func main() {
 		LEFT JOIN "email-addresses-passwords" AS eap ON ea.emailAddress = eap.emailAddress
 		WHERE ea.emailAddress = ?`, emailAddress)
 	if err != nil {
-		fmt.Println("Database error: ", err)
+		logMessage("Database error: ", err)
 		os.Exit(2)
 	}
 	defer rows.Close()
@@ -56,7 +55,7 @@ func main() {
 
 		err := rows.Scan(&id, &hashedPassword)
 		if err != nil {
-			fmt.Println("Database error: ", err)
+			logMessage("Database error: ", err)
 			os.Exit(2)
 		}
 
@@ -71,11 +70,11 @@ func main() {
 								WHERE id = ?`, time.Now().Format(time.RFC3339), id)
 
 			if err != nil {
-				fmt.Println("Database error: ", err)
+				logMessage("Database error: ", err)
 				os.Exit(2)
 			}
 
-			fmt.Println("Authentication successful")
+			logMessage("Authentication successful")
 			os.Exit(0)
 		}
 	}
@@ -84,6 +83,31 @@ func main() {
 	// * either there were no records
 	// * or no record matched the provided password
 
-	fmt.Println("Authentication failed: account not found or password incorrect")
+	logMessage("Authentication failed: account not found or password incorrect")
 	os.Exit(1)
 }
+
+func logMessage(args ...interface{}) error {
+	// Print the message to the console
+	fmt.Println(args...)
+
+	// Log to file if required
+	logFile, logFileSet := os.LookupEnv("HOSTUX_EMAIL_CHECKPW_LOGFILE")
+	if logFileSet {
+		// Open the file in append mode, create it if it doesn't exist
+		file, err := os.OpenFile(logFile, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+		if err != nil {
+			return err
+		}
+		defer file.Close()
+
+		// Write the message to the file
+		_, err = fmt.Fprintln(file, args...)
+
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}