MXS-1220: Add monitor to JSON conversion

Monitors can now be printed in JSON format. The REST API resource
`/monitors` accepts GET requests and returns a JSON representation of the
monitors as a response.

include/maxscale/monitor.h

@@ -244,4 +244,20 @@ void mon_process_state_changes(MXS_MONITOR *monitor, const char *script, uint64_
  */
 void mon_hangup_failed_servers(MXS_MONITOR *monitor);
 
+/**
+ * @brief Convert monitor to JSON
+ *
+ * @param monitor Monitor to convert
+ *
+ * @return JSON representation of the monitor
+ */
+json_t* monitor_to_json(const MXS_MONITOR* monitor);
+
+/**
+ * @brief Convert all monitors to JSON
+ *
+ * @return JSON array containing all monitors
+ */
+json_t* monitor_list_to_json();
+
 MXS_END_DECLS

server/core/monitor.cc

@@ -33,6 +33,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <string>
 
 #include <maxscale/alloc.h>
 #include <mysqld_error.h>
@@ -48,6 +49,8 @@
 #include "maxscale/monitor.h"
 #include "maxscale/modules.h"
 
+using std::string;
+
 static MXS_MONITOR  *allMonitors = NULL;
 static SPINLOCK monLock = SPINLOCK_INIT;
 
@@ -1508,3 +1511,84 @@ void mon_process_state_changes(MXS_MONITOR *monitor, const char *script, uint64_
         }
     }
 }
+
+static const char* monitor_state_to_string(int state)
+{
+    switch (state)
+    {
+    case MONITOR_STATE_RUNNING:
+        return "Running";
+
+    case MONITOR_STATE_STOPPING:
+        return "Stopping";
+
+    case MONITOR_STATE_STOPPED:
+        return "Stopped";
+
+    case MONITOR_STATE_ALLOC:
+        return "Allocated";
+
+    default:
+        ss_dassert(false);
+        return "Unknown";
+    }
+}
+
+json_t* monitor_to_json(const MXS_MONITOR* monitor)
+{
+    json_t* rval = json_object();
+
+    json_object_set_new(rval, "name", json_string(monitor->name));
+    json_object_set_new(rval, "state", json_string(monitor_state_to_string(monitor->state)));
+
+    json_object_set_new(rval, "monitor_interval", json_integer(monitor->interval));
+
+    json_object_set_new(rval, "connect_timeout", json_integer(monitor->connect_timeout));
+    json_object_set_new(rval, "read_timeout", json_integer(monitor->read_timeout));
+    json_object_set_new(rval, "write_timeout", json_integer(monitor->write_timeout));
+    json_object_set_new(rval, "connect_attempts", json_integer(monitor->connect_attempts));
+
+    if (monitor->databases)
+    {
+        json_t* arr = json_array();
+
+        for (MXS_MONITOR_SERVERS *db = monitor->databases; db; db = db->next)
+        {
+            string serv = "/servers/";
+            serv += db->server->unique_name;
+            json_array_append_new(arr, json_string(serv.c_str()));
+        }
+
+        json_object_set_new(rval, "servers", arr);
+    }
+
+
+    if (monitor->handle && monitor->module->diagnostics)
+    {
+        // TODO: Add monitor diagnostics
+        //monitor->module->diagnostics(dcb, monitor);
+    }
+
+    return rval;
+}
+
+json_t* monitor_list_to_json()
+{
+    json_t* rval = json_array();
+
+    spinlock_acquire(&monLock);
+
+    for (MXS_MONITOR* mon = allMonitors; mon; mon = mon->next)
+    {
+        json_t *json = monitor_to_json(mon);
+
+        if (json)
+        {
+            json_array_append_new(rval, json);
+        }
+    }
+
+    spinlock_release(&monLock);
+
+    return rval;
+}

server/core/resource.cc

@@ -139,10 +139,13 @@ class MonitorsResource: public Resource
 protected:
     HttpResponse handle(HttpRequest& request)
     {
+        int flags = request.get_option("pretty") == "true" ? JSON_INDENT(4) : 0;
+
         if (request.uri_part_count() == 1)
         {
+            Closer<json_t*> monitors(monitor_list_to_json());
             // Show all monitors
-            return HttpResponse(HTTP_200_OK);
+            return HttpResponse(HTTP_200_OK, mxs::json_dump(monitors, flags));
         }
         else
         {
@@ -150,8 +153,9 @@ protected:
 
             if (monitor)
             {
+                Closer<json_t*> monitor_js(monitor_to_json(monitor));
                 // Show one monitor
-                return HttpResponse(HTTP_200_OK);
+                return HttpResponse(HTTP_200_OK, mxs::json_dump(monitor_js, flags));
             }
             else
             {