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()