feat: option to host webui on s3 port

This adds the webui-s3-prefix option to specify a prefix and host
the webui on the same port as the s3 service. Like the health
endpoint, this will mask any bucket with the same name as the
webui prefix.

The benefit of hosting this on the same interface as the s3
service is no longer needing the CORS headers for the browser
access if the webui and s3 access are on the same IP:PORT.

s3api/server.go

@@ -35,6 +35,7 @@ import (
 	"github.com/versity/versitygw/s3err"
 	"github.com/versity/versitygw/s3event"
 	"github.com/versity/versitygw/s3log"
+	"github.com/versity/versitygw/webui"
 )
 
 const (
@@ -42,15 +43,17 @@ const (
 )
 
 type S3ApiServer struct {
-	Router         *S3ApiRouter
-	app            *fiber.App
-	backend        backend.Backend
-	CertStorage    *utils.CertStorage
-	quiet          bool
-	keepAlive      bool
-	health         string
-	maxConnections int
-	maxRequests    int
+	Router           *S3ApiRouter
+	app              *fiber.App
+	backend          backend.Backend
+	CertStorage      *utils.CertStorage
+	quiet            bool
+	keepAlive        bool
+	health           string
+	maxConnections   int
+	maxRequests      int
+	webuiMountPrefix string
+	webuiSrvCfg      *webui.ServerConfig
 }
 
 func New(
@@ -120,6 +123,11 @@ func New(
 		})
 	}
 
+	// Set up WebUI on the S3 port if configured
+	if server.webuiSrvCfg != nil {
+		webui.MountOn(app, server.webuiMountPrefix, server.webuiSrvCfg)
+	}
+
 	// initialize total requests cap limiter middleware
 	app.Use(middlewares.RateLimiter(server.maxRequests, mm, l))
 
@@ -185,6 +193,16 @@ func WithCORSAllowOrigin(origin string) Option {
 	return func(s *S3ApiServer) { s.Router.corsAllowOrigin = origin }
 }
 
+// WithWebUI mounts the WebUI on the S3 server's Fiber app at the given path prefix,
+// before S3 routes are registered. The prefix must start with "/" and must not be
+// empty or just "/".
+func WithWebUI(prefix string, cfg *webui.ServerConfig) Option {
+	return func(s *S3ApiServer) {
+		s.webuiMountPrefix = prefix
+		s.webuiSrvCfg = cfg
+	}
+}
+
 // WithConcurrencyLimiter sets the server's maximum connection limit
 // and the hard limit for in-flight requests.
 func WithConcurrencyLimiter(maxConnections, maxRequests int) Option {