feat: require explicit subcommands and update usage documentation

- Add usage instructions for version, help, and server commands
- Update documentation and examples to use the server subcommand when running the application
- Change Dockerfile to start the server using the server subcommand
- Implement subcommand parsing in main.go, requiring an explicit command to start the server
- Add a usage/help function to display available commands and options

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

Author: appleboy

CLAUDE.md

@@ -13,7 +13,9 @@ AuthGate is an OAuth 2.0 Device Authorization Grant (RFC 8628) server built with
 make build              # Build to bin/authgate with version info in LDFLAGS
 
 # Run
-./bin/authgate          # Run after make build
+./bin/authgate -v       # Show version information
+./bin/authgate -h       # Show help
+./bin/authgate server   # Start the OAuth server
 
 # Test & Lint
 make test               # Run tests with coverage report (outputs coverage.txt)

README.md

@@ -23,6 +23,10 @@
       - [Docker Features](#docker-features)
       - [Docker Compose Example](#docker-compose-example)
     - [Test with the Example CLI](#test-with-the-example-cli)
+  - [User Interface](#user-interface)
+    - [1. Login Page](#1-login-page)
+    - [2. Device Authorization Page](#2-device-authorization-page)
+    - [3. Authorization Success](#3-authorization-success)
   - [How It Works](#how-it-works)
     - [Device Flow Sequence](#device-flow-sequence)
     - [Key Endpoints](#key-endpoints)
@@ -180,11 +184,18 @@ go build -o bin/authgate .
 ### Run the Server
 
 ```bash
-# After make build
-./bin/authgate
+# Show version information
+./bin/authgate -v
+./bin/authgate --version
+
+# Show help
+./bin/authgate -h
+
+# Start the server
+./bin/authgate server
 
 # Or directly with Go
-go run .
+go run . server
 ```
 
 The server will start on `http://localhost:8080` by default.
@@ -665,7 +676,7 @@ After=network.target
 Type=simple
 User=authgate
 WorkingDirectory=/var/lib/authgate
-ExecStart=/usr/local/bin/authgate
+ExecStart=/usr/local/bin/authgate server
 Restart=on-failure
 RestartSec=10
 
@@ -880,7 +891,7 @@ db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{})
 Enable debug logging by setting Gin to debug mode:
 
 ```bash
-GIN_MODE=debug ./bin/authgate
+GIN_MODE=debug ./bin/authgate server
 ```
 
 ---

docker/Dockerfile

@@ -38,4 +38,4 @@ VOLUME ["/app/data"]
 # Set default environment
 ENV DATABASE_PATH=/app/data/oauth.db
 
-CMD ["/bin/authgate"]
+CMD ["/bin/authgate", "server"]

main.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"embed"
 	"flag"
+	"fmt"
 	"html/template"
 	"io/fs"
 	"log"
@@ -31,9 +32,10 @@ var templatesFS embed.FS
 var staticFS embed.FS
 
 func main() {
-	// Parse command line flags
+	// Define flags
 	showVersion := flag.Bool("version", false, "Show version information")
 	flag.BoolVar(showVersion, "v", false, "Show version information (shorthand)")
+	flag.Usage = printUsage
 	flag.Parse()
 
 	// Show version and exit if requested
@@ -42,6 +44,35 @@ func main() {
 		os.Exit(0)
 	}
 
+	// Check if command is provided
+	args := flag.Args()
+	if len(args) == 0 {
+		printUsage()
+		os.Exit(1)
+	}
+
+	// Handle subcommands
+	switch args[0] {
+	case "server":
+		runServer()
+	default:
+		fmt.Printf("Unknown command: %s\n\n", args[0])
+		printUsage()
+		os.Exit(1)
+	}
+}
+
+func printUsage() {
+	fmt.Printf("Usage: %s [OPTIONS] COMMAND\n\n", os.Args[0])
+	fmt.Println("OAuth 2.0 Device Authorization Grant server")
+	fmt.Println("\nCommands:")
+	fmt.Println("  server    Start the OAuth server")
+	fmt.Println("\nOptions:")
+	fmt.Println("  -v, --version    Show version information")
+	fmt.Println("  -h, --help       Show this help message")
+}
+
+func runServer() {
 	// Load configuration
 	cfg := config.Load()