initialize forwarder after init() to avoid crashes (#11330)

DNSCache dialer is a global value initialized in
init(), whereas `go` keeps `var =` before `init()`
, also we don't need to keep proxy routers as
global entities - register the forwarder as
necessary to avoid crashes.

cmd/common-main.go

@@ -41,6 +41,7 @@ import (
 	"github.com/minio/minio/pkg/certs"
 	"github.com/minio/minio/pkg/console"
 	"github.com/minio/minio/pkg/env"
+	"github.com/minio/minio/pkg/handlers"
 )
 
 // serverDebugLog will enable debug printing
@@ -51,10 +52,19 @@ func init() {
 	logger.RegisterError(config.FmtError)
 
 	rand.Seed(time.Now().UTC().UnixNano())
+
 	globalDNSCache = xhttp.NewDNSCache(10*time.Second, 10*time.Second, logger.LogOnceIf)
 
 	initGlobalContext()
 
+	globalForwarder = handlers.NewForwarder(&handlers.Forwarder{
+		PassHost:     true,
+		RoundTripper: newGatewayHTTPTransport(1 * time.Hour),
+		Logger: func(err error) {
+			logger.LogIf(GlobalContext, err)
+		},
+	})
+
 	globalReplicationState = newReplicationState()
 	globalTransitionState = newTransitionState()
 

cmd/generic-handlers.go

@@ -30,7 +30,6 @@ import (
 	xhttp "github.com/minio/minio/cmd/http"
 	"github.com/minio/minio/cmd/http/stats"
 	"github.com/minio/minio/cmd/logger"
-	"github.com/minio/minio/pkg/handlers"
 )
 
 // Adds limiting body size middleware
@@ -532,14 +531,6 @@ func setRequestValidityHandler(h http.Handler) http.Handler {
 	})
 }
 
-var fwd = handlers.NewForwarder(&handlers.Forwarder{
-	PassHost:     true,
-	RoundTripper: newGatewayHTTPTransport(1 * time.Hour),
-	Logger: func(err error) {
-		logger.LogIf(GlobalContext, err)
-	},
-})
-
 // setBucketForwardingHandler middleware forwards the path style requests
 // on a bucket to the right bucket location, bucket to IP configuration
 // is obtained from centralized etcd configuration service.
@@ -589,7 +580,7 @@ func setBucketForwardingHandler(h http.Handler) http.Handler {
 					r.URL.Scheme = "https"
 				}
 				r.URL.Host = getHostFromSrv(sr)
-				fwd.ServeHTTP(w, r)
+				globalForwarder.ServeHTTP(w, r)
 				return
 			}
 			h.ServeHTTP(w, r)
@@ -639,7 +630,7 @@ func setBucketForwardingHandler(h http.Handler) http.Handler {
 				r.URL.Scheme = "https"
 			}
 			r.URL.Host = getHostFromSrv(sr)
-			fwd.ServeHTTP(w, r)
+			globalForwarder.ServeHTTP(w, r)
 			return
 		}
 		h.ServeHTTP(w, r)

cmd/globals.go

@@ -25,6 +25,7 @@ import (
 
 	"github.com/minio/minio-go/v7/pkg/set"
 	"github.com/minio/minio/pkg/bucket/bandwidth"
+	"github.com/minio/minio/pkg/handlers"
 
 	humanize "github.com/dustin/go-humanize"
 	"github.com/minio/minio/cmd/config/cache"
@@ -285,6 +286,8 @@ var (
 	globalProxyTransport http.RoundTripper
 
 	globalDNSCache *xhttp.DNSCache
+
+	globalForwarder *handlers.Forwarder
 	// Add new variable global values here.
 )