MXS-2167: Add test case

Added a test case that reproduces the problem.

maxscale-system-test/mxs2167_extra_port.cpp

@@ -0,0 +1,90 @@
+/**
+ * MXS-2167: Monitors should be able to use extra_port
+ */
+
+#include "testconnections.h"
+#include <iostream>
+
+using std::cout;
+using std::endl;
+
+
+int main(int argc, char** argv)
+{
+    TestConnections test(argc, argv);
+
+    cout << "Stopping MaxScale" << endl;
+    test.maxscales->stop();
+
+    cout << "Configuring servers" << endl;
+    // Add the extra_port parameter to all servers
+    for (int i = 0; i < test.repl->N; i++)
+    {
+        test.repl->stash_server_settings(i);
+        test.repl->add_server_setting(i, "extra_port=33066");
+        test.repl->ssh_node_f(i, true, "service mysql restart");
+    }
+
+    test.repl->connect();
+    test.try_query(test.repl->nodes[0], "%s", "CREATE USER 'monitor'@'%' IDENTIFIED BY 'monitor'");
+    test.try_query(test.repl->nodes[0], "%s", "GRANT ALL ON *.* TO 'monitor'@'%'");
+    test.repl->disconnect();
+
+    cout << "Starting MaxScale" << endl;
+    test.maxscales->start();
+
+    // Stop the monitor to force the connections to be closed
+    test.maxctrl("stop monitor MySQL-Monitor");
+
+    // Limit the connections to 20 (is erased on restart)
+    test.repl->connect();
+    test.try_query(test.repl->nodes[0], "SET GLOBAL max_connections=20");
+    test.repl->disconnect();
+
+    std::vector<MYSQL*> connections;
+
+    // Open connections until we hit the limit
+    for (int i = 0; i < 40; i++)
+    {
+        cout << "Opening connection " << i << endl;
+
+        MYSQL* conn = test.maxscales->open_rwsplit_connection();
+
+        if (execute_query_silent(conn, "SELECT 1") == 0)
+        {
+            connections.push_back(conn);
+        }
+        else
+        {
+            mysql_close(conn);
+            break;
+        }
+    }
+
+    // Start the monitor to force it to reconnect
+    test.maxctrl("start monitor MySQL-Monitor");
+    test.maxscales->wait_for_monitor();
+
+    // Make sure the old connections still work
+    for (auto a : connections)
+    {
+        test.try_query(a, "SELECT 2");
+        mysql_close(a);
+    }
+
+    cout << "Stopping MaxScale" << endl;
+    test.maxscales->stop();
+
+    // Remove extra_port
+    for (int i = 0; i < test.repl->N; i++)
+    {
+        test.repl->restore_server_settings(i);
+        test.repl->ssh_node_f(i, true, "service mysql restart");
+    }
+
+    test.repl->connect();
+    test.try_query(test.repl->nodes[0], "%s", "DROP USER 'monitor'@'%'");
+    test.repl->disconnect();
+
+    return test.global_result;
+}