MXS-2428 Add 'dynamic_node_detection' 'health_check_port'

'dynamic_node_detection' specifies whether the Clustrix monitor
should dynamically figure out what nodes there are, or just rely
upon static information.

'health_check_port' specifies the port to be used when perforing
the health check ping.

Documentation/Monitors/Clustrix-Monitor.md

@@ -10,9 +10,11 @@ instances within MaxScale.
 
 A minimal configuration for a monitor requires one server in the Clustrix
 cluster, and a username and a password to connect to the server. Note that
-the Clustrix monitor will only use that server in order to dynamically find
-out the configuration of the cluster; after startup it will completely rely
-upon information obtained at runtime.
+by default the Clustrix monitor will only use that server in order to
+dynamically find out the configuration of the cluster; after startup it
+will completely rely upon information obtained at runtime. To change the
+default behaviour, please see the parameter
+[dynamic_node_detection](#dynamic_node_detection).
 
 To ensure that the Clustrix monitor will be able to start, it is adviseable
 to provide _more_ than one server to cater for the case that not all nodes
@@ -97,6 +99,52 @@ considers a particular node to be down. The default value is 2.
 health_check_threshold=3
 ```
 
+### `dynamic_node_detection`
+
+By default, the Clustrix monitor will only use the bootstrap nodes
+in order to connect to the Clustrux cluster and then find out the
+cluster configuration dynamically at runtime.
+
+That behaviour can be turned off with this optional parameter, in
+which case all Clustrix nodes must manually be defined as shown below.
+
+```
+[Node-1]
+type=server
+address=192.168.121.77
+port=3306
+...
+
+[Node-2]
+...
+
+[Node-3]
+...
+
+[Clustrix-Monitor]
+type=monitor
+module=clustrixmon
+servers=Node-1, Node-2, Node-3
+dynamic_node_detection=false
+```
+
+The default value of `dynamic_node_detection` is `true`.
+
+See also [health_check_port](#health_check_port).
+
+### `health_check_port`
+
+With this optional parameter it can be specified what health check
+port to use, if `dynamic_node_detection` has been disabled.
+
+```
+health_check_port=4711
+```
+The default value is `3581`.
+
+Note that this parameter is _ignored_ unless `dynamic_node_detection`
+is `false`. Note also that the port must be the same for all nodes.
+
 ## Commands
 
 The Clustrix monitor supports the following module commands.

server/modules/monitor/clustrixmon/clustrixmon.cc

@@ -111,6 +111,16 @@ extern "C" MXS_MODULE* MXS_CREATE_MODULE()
                 MXS_MODULE_PARAM_COUNT,
                 DEFAULT_HEALTH_CHECK_THRESHOLD_ZVALUE
             },
+            {
+                DYNAMIC_NODE_DETECTION_NAME,
+                MXS_MODULE_PARAM_BOOL,
+                DEFAULT_DYNAMIC_NODE_DETECTION_ZVALUE
+            },
+            {
+                HEALTH_CHECK_PORT_NAME,
+                MXS_MODULE_PARAM_COUNT,
+                DEFAULT_HEALTH_CHECK_PORT_ZVALUE
+            },
             {MXS_END_MODULE_PARAMS}
         }
     };

server/modules/monitor/clustrixmon/clustrixmon.hh

@@ -21,6 +21,14 @@
 const long DEFAULT_CLUSTER_MONITOR_INTERVAL_VALUE = 60000;
 #define    DEFAULT_CLUSTER_MONITOR_INTERVAL_ZVALUE  "60000"
 
-#define    HEALTH_CHECK_THRESHOLD_NAME            "health_check_threshold"
-const long DEFAULT_HEALTH_CHECK_THRESHOLD_VALUE = 2;
-#define    DEFAULT_HEALTH_CHECK_THRESHOLD_ZVALUE  "2"
+#define    HEALTH_CHECK_THRESHOLD_NAME              "health_check_threshold"
+const long DEFAULT_HEALTH_CHECK_THRESHOLD_VALUE   = 2;
+#define    DEFAULT_HEALTH_CHECK_THRESHOLD_ZVALUE    "2"
+
+#define    DYNAMIC_NODE_DETECTION_NAME              "dynamic_node_detection"
+const bool DEFAULT_DYNAMIC_NODE_DETECTION_VALUE   = true;
+#define    DEFAULT_DYNAMIC_NODE_DETECTION_ZVALUE    "true"
+
+#define    HEALTH_CHECK_PORT_NAME                   "health_check_port"
+const long DEFAULT_HEALTH_CHECK_PORT_VALUE        = 3581;
+#define    DEFAULT_HEALTH_CHECK_PORT_ZVALUE         "3581"

server/modules/monitor/clustrixmon/clustrixmonitor.cc

@@ -175,6 +175,8 @@ bool ClustrixMonitor::configure(const MXS_CONFIG_PARAMETER* pParams)
 
     m_config.set_cluster_monitor_interval(pParams->get_integer(CLUSTER_MONITOR_INTERVAL_NAME));
     m_config.set_health_check_threshold(pParams->get_integer(HEALTH_CHECK_THRESHOLD_NAME));
+    m_config.set_dynamic_node_detection(pParams->get_bool(DYNAMIC_NODE_DETECTION_NAME));
+    m_config.set_health_check_port(pParams->get_integer(HEALTH_CHECK_PORT_NAME));
 
     return true;
 }

server/modules/monitor/clustrixmon/clustrixmonitor.hh

@@ -33,6 +33,8 @@ public:
         Config()
             : m_cluster_monitor_interval(DEFAULT_CLUSTER_MONITOR_INTERVAL_VALUE)
             , m_health_check_threshold(DEFAULT_HEALTH_CHECK_THRESHOLD_VALUE)
+            , m_dynamic_node_detection(DEFAULT_DYNAMIC_NODE_DETECTION_VALUE)
+            , m_health_check_port(DEFAULT_HEALTH_CHECK_PORT_VALUE)
         {
         };
 
@@ -56,9 +58,31 @@ public:
             m_health_check_threshold = l;
         }
 
+        bool dynamic_node_detection() const
+        {
+            return m_dynamic_node_detection;
+        }
+
+        void set_dynamic_node_detection(bool b)
+        {
+            m_dynamic_node_detection = b;
+        }
+
+        int health_check_port() const
+        {
+            return m_health_check_port;
+        }
+
+        void set_health_check_port(int p)
+        {
+            m_health_check_port = p;
+        }
+
     private:
         long m_cluster_monitor_interval;
         long m_health_check_threshold;
+        bool m_dynamic_node_detection;
+        int  m_health_check_port;
     };
 
     ~ClustrixMonitor();