Check if SSL is configured to validate input arguments (#5252)

This PR handles following situations

- secure endpoints provided, server should fail to start
  if TLS is not configured

- insecure endpoints provided, server starts ignoring
  if TLS is configured or not.

Fixes #5251

cmd/endpoint.go

@@ -65,18 +65,9 @@ func (endpoint Endpoint) Type() EndpointType {
 	return URLEndpointType
 }
 
-// SetHTTPS - sets secure http for URLEndpointType.
-func (endpoint Endpoint) SetHTTPS() {
-	if endpoint.Host != "" {
-		endpoint.Scheme = "https"
-	}
-}
-
-// SetHTTP - sets insecure http for URLEndpointType.
-func (endpoint Endpoint) SetHTTP() {
-	if endpoint.Host != "" {
-		endpoint.Scheme = "http"
-	}
+// IsHTTPS - returns true if secure for URLEndpointType.
+func (endpoint Endpoint) IsHTTPS() bool {
+	return endpoint.Scheme == "https"
 }
 
 // NewEndpoint - returns new endpoint based on given arguments.
@@ -190,18 +181,9 @@ func (endpoints EndpointList) Less(i, j int) bool {
 	return endpoints[i].String() < endpoints[j].String()
 }
 
-// SetHTTPS - sets secure http for URLEndpointType.
-func (endpoints EndpointList) SetHTTPS() {
-	for i := range endpoints {
-		endpoints[i].SetHTTPS()
-	}
-}
-
-// SetHTTP - sets insecure http for URLEndpointType.
-func (endpoints EndpointList) SetHTTP() {
-	for i := range endpoints {
-		endpoints[i].SetHTTP()
-	}
+// IsHTTPS - returns true if secure for URLEndpointType.
+func (endpoints EndpointList) IsHTTPS() bool {
+	return endpoints[0].IsHTTPS()
 }
 
 // NewEndpointList - returns new endpoint list based on input args.

cmd/server-main.go

@@ -158,6 +158,11 @@ func serverMain(ctx *cli.Context) {
 	globalPublicCerts, globalRootCAs, globalTLSCertificate, globalIsSSL, err = getSSLConfig()
 	fatalIf(err, "Invalid SSL certificate file")
 
+	// Is distributed setup, error out if no certificates are found for HTTPS endpoints.
+	if globalIsDistXL && globalEndpoints.IsHTTPS() && !globalIsSSL {
+		fatalIf(errInvalidArgument, "No certificates found for HTTPS endpoints (%s)", globalEndpoints)
+	}
+
 	if !quietFlag {
 		// Check for new updates from dl.minio.io.
 		mode := globalMinioModeFS
@@ -182,7 +187,6 @@ func serverMain(ctx *cli.Context) {
 	initNSLock(globalIsDistXL)
 
 	// Configure server.
-	// Declare handler to avoid lint errors.
 	var handler http.Handler
 	handler, err = configureServerHandler(globalEndpoints)
 	fatalIf(err, "Unable to configure one of server's RPC services.")