MXS-1446: Add passive parameter

The `passive` parameter can be given in the configuration file or on the
command line. It is displayed in the diagnostic output and changes to it
are persisted.

The variable itself does nothing.

include/maxscale/config.h

@@ -126,6 +126,7 @@ extern const char CN_NAME[];
 extern const char CN_NON_BLOCKING_POLLS[];
 extern const char CN_OPTIONS[];
 extern const char CN_PARAMETERS[];
+extern const char CN_PASSIVE[];
 extern const char CN_PASSWORD[];
 extern const char CN_POLL_SLEEP[];
 extern const char CN_PORT[];
@@ -208,6 +209,7 @@ typedef struct
     unsigned int  auth_read_timeout;                   /**< Read timeout for the user authentication */
     unsigned int  auth_write_timeout;                  /**< Write timeout for the user authentication */
     bool          skip_permission_checks;              /**< Skip service and monitor permission checks */
+    bool          passive;                             /**< True if MaxScale is in passive mode */
     char          qc_name[PATH_MAX];                   /**< The name of the query classifier to load */
     char*         qc_args;                             /**< Arguments for the query classifier */
     qc_sql_mode_t qc_sql_mode;                         /**< The query classifier sql mode */

server/core/config.cc

@@ -104,6 +104,7 @@ const char CN_NAME[]                          = "name";
 const char CN_NON_BLOCKING_POLLS[]            = "non_blocking_polls";
 const char CN_OPTIONS[]                       = "options";
 const char CN_PARAMETERS[]                    = "parameters";
+const char CN_PASSIVE[]                       = "passive";
 const char CN_PASSWORD[]                      = "password";
 const char CN_POLL_SLEEP[]                    = "poll_sleep";
 const char CN_PORT[]                          = "port";
@@ -1566,6 +1567,10 @@ handle_global_item(const char *name, const char *value)
     {
         gateway.admin_log_auth_failures = config_truth_value(value);
     }
+    else if (strcmp(name, CN_PASSIVE) == 0)
+    {
+        gateway.passive = config_truth_value((char*)value);
+    }
     else
     {
         for (i = 0; lognames[i].name; i++)
@@ -1755,6 +1760,7 @@ void config_set_global_defaults()
     gateway.admin_ssl_key[0] = '\0';
     gateway.admin_ssl_cert[0] = '\0';
     gateway.admin_ssl_ca_cert[0] = '\0';
+    gateway.passive = false;
 
     gateway.thread_stack_size = 0;
     pthread_attr_t attr;
@@ -3897,6 +3903,7 @@ json_t* config_maxscale_to_json(const char* host)
     json_object_set_new(param, CN_ADMIN_SSL_KEY, json_string(cnf->admin_ssl_key));
     json_object_set_new(param, CN_ADMIN_SSL_CERT, json_string(cnf->admin_ssl_cert));
     json_object_set_new(param, CN_ADMIN_SSL_CA_CERT, json_string(cnf->admin_ssl_ca_cert));
+    json_object_set_new(param, CN_PASSIVE, json_boolean(cnf->passive));
 
     json_object_set_new(param, CN_QUERY_CLASSIFIER, json_string(cnf->qc_name));
 
@@ -3942,6 +3949,7 @@ static bool create_global_config(const char *filename)
     dprintf(file, "%s=%u\n", CN_AUTH_READ_TIMEOUT, gateway.auth_read_timeout);
     dprintf(file, "%s=%u\n", CN_AUTH_WRITE_TIMEOUT, gateway.auth_write_timeout);
     dprintf(file, "%s=%s\n", CN_ADMIN_AUTH, gateway.admin_auth ? "true" : "false");
+    dprintf(file, "%s=%u\n", CN_PASSIVE, gateway.passive);
 
     close(file);
 

server/core/config_runtime.cc

@@ -749,6 +749,23 @@ bool runtime_alter_maxscale(const char* name, const char* value)
             runtime_error("Invalid boolean value for '%s': %s", CN_ADMIN_LOG_AUTH_FAILURES, value);
         }
     }
+    else if (key == CN_PASSIVE)
+    {
+        int boolval = config_truth_value(value);
+
+        if (boolval != -1)
+        {
+            MXS_NOTICE("Updated '%s' from '%s' to '%s'", CN_PASSIVE,
+                       cnf.passive ? "true" : "false",
+                       boolval ? "true" : "false");
+            cnf.passive = boolval;
+            rval = true;
+        }
+        else
+        {
+            runtime_error("Invalid boolean value for '%s': %s", CN_PASSIVE, value);
+        }
+    }
     else
     {
         runtime_error("Unknown global parameter: %s=%s", name, value);

server/core/gateway.cc

@@ -129,6 +129,7 @@ static struct option long_options[] =
     {"version-full",     no_argument,       0, 'V'},
     {"help",             no_argument,       0, '?'},
     {"connector_plugindir", required_argument, 0, 'H'},
+    {"passive",          no_argument,       0, 'p'},
     {"debug",            required_argument, 0, 'g'},
     {0, 0, 0, 0}
 };
@@ -922,6 +923,7 @@ static void usage(void)
             "  -S, --maxlog=[yes|no]       log messages to MaxScale log (default: yes)\n"
             "  -G, --log_augmentation=0|1  augment messages with the name of the function\n"
             "                              where the message was logged (default: 0)\n"
+            "  -p, --passive               start MaxScale as a passive standby\n"
             "  -g, --debug=arg1,arg2,...   enable or disable debug features. Supported arguments:\n",
             progname);
     for (int i = 0; debug_arguments[i].action != NULL; i++)
@@ -1289,7 +1291,7 @@ int main(int argc, char **argv)
     file_write_header(stderr);
 
     // Option string for getopt
-    const char accepted_opts[] = "dcf:g:l:vVs:S:?L:D:C:B:U:A:P:G:N:E:F:M:H:";
+    const char accepted_opts[] = "dcf:g:l:vVs:S:?L:D:C:B:U:A:P:G:N:E:F:M:H:p";
 
     /*<
      * Register functions which are called at exit.
@@ -1577,6 +1579,10 @@ int main(int argc, char **argv)
             config_check = true;
             break;
 
+        case 'p':
+            cnf->passive = true;
+            break;
+
         case 'g':
             if (!handle_debug_args(optarg))
             {