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MaxScale/server/modules/monitor/galeramon/galeramon.cc

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/*
* Copyright (c) 2016 MariaDB Corporation Ab
*
* Use of this software is governed by the Business Source License included
* in the LICENSE.TXT file and at www.mariadb.com/bsl11.
*
* Change Date: 2022-01-01
*
* On the date above, in accordance with the Business Source License, use
* of this software will be governed by version 2 or later of the General
* Public License.
*/
/**
* @file galera_mon.c - A MySQL Galera cluster monitor
*/
#define MXS_MODULE_NAME "galeramon"
#include "galeramon.hh"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <mysql.h>
#include <mysqld_error.h>
#include <maxscale/alloc.h>
#include <maxscale/config.h>
#include <maxscale/dcb.h>
#include <maxscale/log.h>
#include <maxscale/modinfo.h>
#include <maxscale/mysql_utils.h>
#include <maxscale/secrets.h>
#include <maxscale/spinlock.h>
#define DONOR_NODE_NAME_MAX_LEN 60
#define DONOR_LIST_SET_VAR "SET GLOBAL wsrep_sst_donor = \""
/** Log a warning when a bad 'wsrep_local_index' is found */
static bool warn_erange_on_local_index = true;
static MXS_MONITORED_SERVER *set_cluster_master(MXS_MONITORED_SERVER *, MXS_MONITORED_SERVER *, int);
static void disableMasterFailback(void *, int);
static int compare_node_index(const void*, const void*);
static int compare_node_priority(const void*, const void*);
static bool using_xtrabackup(MXS_MONITORED_SERVER *database, const char* server_string);
GaleraMonitor::GaleraMonitor(MXS_MONITOR *mon)
: maxscale::MonitorInstanceSimple(mon)
, m_id(MXS_MONITOR_DEFAULT_ID)
, m_disableMasterFailback(0)
, m_availableWhenDonor(0)
, m_disableMasterRoleSetting(0)
, m_root_node_as_master(false)
, m_use_priority(false)
, m_set_donor_nodes(false)
, m_log_no_members(false)
, m_cluster_size(0)
{
}
GaleraMonitor::~GaleraMonitor()
{
}
// static
GaleraMonitor* GaleraMonitor::create(MXS_MONITOR* monitor)
{
return new GaleraMonitor(monitor);
}
void GaleraMonitor::diagnostics(DCB *dcb) const
{
dcb_printf(dcb, "Master Failback:\t%s\n", (m_disableMasterFailback == 1) ? "off" : "on");
dcb_printf(dcb, "Available when Donor:\t%s\n", (m_availableWhenDonor == 1) ? "on" : "off");
dcb_printf(dcb, "Master Role Setting Disabled:\t%s\n",
m_disableMasterRoleSetting ? "on" : "off");
dcb_printf(dcb, "Set wsrep_sst_donor node list:\t%s\n", (m_set_donor_nodes == 1) ? "on" : "off");
if (!m_cluster_uuid.empty())
{
dcb_printf(dcb, "Galera Cluster UUID:\t%s\n", m_cluster_uuid.c_str());
dcb_printf(dcb, "Galera Cluster size:\t%d\n", m_cluster_size);
}
else
{
dcb_printf(dcb, "Galera Cluster NOT set:\tno member nodes\n");
}
}
json_t* GaleraMonitor::diagnostics_json() const
{
json_t* rval = MonitorInstance::diagnostics_json();
json_object_set_new(rval, "disable_master_failback", json_boolean(m_disableMasterFailback));
json_object_set_new(rval, "disable_master_role_setting", json_boolean(m_disableMasterRoleSetting));
json_object_set_new(rval, "root_node_as_master", json_boolean(m_root_node_as_master));
json_object_set_new(rval, "use_priority", json_boolean(m_use_priority));
json_object_set_new(rval, "set_donor_nodes", json_boolean(m_set_donor_nodes));
if (!m_cluster_uuid.empty())
{
json_object_set_new(rval, "cluster_uuid", json_string(m_cluster_uuid.c_str()));
json_object_set_new(rval, "cluster_size", json_integer(m_cluster_size));
}
return rval;
}
bool GaleraMonitor::configure(const MXS_CONFIG_PARAMETER* params)
{
m_disableMasterFailback = config_get_bool(params, "disable_master_failback");
m_availableWhenDonor = config_get_bool(params, "available_when_donor");
m_disableMasterRoleSetting = config_get_bool(params, "disable_master_role_setting");
m_root_node_as_master = config_get_bool(params, "root_node_as_master");
m_use_priority = config_get_bool(params, "use_priority");
m_set_donor_nodes = config_get_bool(params, "set_donor_nodes");
m_log_no_members = true;
/* Reset all data in the hashtable */
m_info.clear();
return true;
}
bool GaleraMonitor::has_sufficient_permissions() const
{
return check_monitor_permissions(m_monitor, "SHOW STATUS LIKE 'wsrep_local_state'");
}
void GaleraMonitor::update_server_status(MXS_MONITORED_SERVER* monitored_server)
{
MYSQL_ROW row;
MYSQL_RES *result;
char *server_string;
/* get server version string */
mxs_mysql_set_server_version(monitored_server->con, monitored_server->server);
server_string = monitored_server->server->version_string;
/* Check if the the Galera FSM shows this node is joined to the cluster */
const char *cluster_member =
"SHOW STATUS WHERE Variable_name IN"
" ('wsrep_cluster_state_uuid',"
" 'wsrep_cluster_size',"
" 'wsrep_local_index',"
" 'wsrep_local_state')";
if (mxs_mysql_query(monitored_server->con, cluster_member) == 0
&& (result = mysql_store_result(monitored_server->con)) != NULL)
{
if (mysql_field_count(monitored_server->con) < 2)
{
mysql_free_result(result);
MXS_ERROR("Unexpected result for \"%s\". "
"Expected 2 columns. MySQL Version: %s",
cluster_member, server_string);
return;
}
GaleraNode info = {};
while ((row = mysql_fetch_row(result)))
{
if (strcmp(row[0], "wsrep_cluster_size") == 0)
{
info.cluster_size = atoi(row[1]);
}
if (strcmp(row[0], "wsrep_local_index") == 0)
{
char* endchar;
long local_index = strtol(row[1], &endchar, 10);
if (*endchar != '\0' ||
(errno == ERANGE && (local_index == LONG_MAX || local_index == LONG_MIN)))
{
if (warn_erange_on_local_index)
{
MXS_WARNING("Invalid 'wsrep_local_index' on server '%s': %s",
monitored_server->server->name, row[1]);
warn_erange_on_local_index = false;
}
local_index = -1;
/* Force joined = 0 */
info.joined = 0;
}
info.local_index = local_index;
}
mxb_assert(row[0] && row[1]);
if (strcmp(row[0], "wsrep_local_state") == 0)
{
if (strcmp(row[1], "4") == 0)
{
info.joined = 1;
}
/* Check if the node is a donor and is using xtrabackup, in this case it can stay alive */
else if (strcmp(row[1], "2") == 0 && m_availableWhenDonor == 1 &&
using_xtrabackup(monitored_server, server_string))
{
info.joined = 1;
}
else
{
/* Force joined = 0 */
info.joined = 0;
}
info.local_state = atoi(row[1]);
}
/* We can check:
* wsrep_local_state == 0
* wsrep_cluster_size == 0
* wsrep_cluster_state_uuid == ""
*/
if (strcmp(row[0], "wsrep_cluster_state_uuid") == 0)
{
if (row[1] == NULL || !strlen(row[1]))
{
info.cluster_uuid.clear();
info.joined = 0;
}
else
{
info.cluster_uuid = MXS_STRDUP(row[1]);
}
}
}
monitored_server->server->node_id = info.joined ? info.local_index : -1;
m_info[monitored_server] = info;
mysql_free_result(result);
}
else
{
mon_report_query_error(monitored_server);
}
}
void GaleraMonitor::pre_tick()
{
// Clear the info before monitoring to make sure it's up to date
m_info.clear();
}
void GaleraMonitor::post_tick()
{
int is_cluster = 0;
/* Try to set a Galera cluster based on
* UUID and cluster_size each node reports:
* no multiple clusters UUID are allowed.
*/
set_galera_cluster();
/*
* Let's select a master server:
* it could be the candidate master following MXS_MIN(node_id) rule or
* the server that was master in the previous monitor polling cycle
* Decision depends on master_stickiness value set in configuration
*/
/* get the candidate master, following MXS_MIN(node_id) rule */
MXS_MONITORED_SERVER *candidate_master = get_candidate_master();
m_master = set_cluster_master(m_master, candidate_master, m_disableMasterFailback);
MXS_MONITORED_SERVER *ptr = m_monitor->monitored_servers;
while (ptr)
{
const int repl_bits = (SERVER_SLAVE | SERVER_MASTER | SERVER_MASTER_STICKINESS);
if ((ptr->pending_status & SERVER_JOINED) && !m_disableMasterRoleSetting)
{
if (ptr != m_master)
{
/* set the Slave role and clear master stickiness */
monitor_clear_pending_status(ptr, repl_bits);
monitor_set_pending_status(ptr, SERVER_SLAVE);
}
else
{
if (candidate_master &&
m_master->server->node_id != candidate_master->server->node_id)
{
/* set master role and master stickiness */
monitor_clear_pending_status(ptr, repl_bits);
monitor_set_pending_status(ptr, SERVER_MASTER | SERVER_MASTER_STICKINESS);
}
else
{
/* set master role and clear master stickiness */
monitor_clear_pending_status(ptr, repl_bits);
monitor_set_pending_status(ptr, SERVER_MASTER);
}
}
is_cluster++;
}
else
{
monitor_clear_pending_status(ptr, repl_bits);
monitor_set_pending_status(ptr, 0);
}
ptr = ptr->next;
}
if (is_cluster == 0 && m_log_no_members)
{
MXS_ERROR("There are no cluster members");
m_log_no_members = false;
}
else
{
if (is_cluster > 0 && m_log_no_members == 0)
{
MXS_NOTICE("Found cluster members");
m_log_no_members = true;
}
}
/* Set the global var "wsrep_sst_donor"
* with a sorted list of "wsrep_node_name" for slave nodes
*/
if (m_set_donor_nodes)
{
update_sst_donor_nodes(is_cluster);
}
}
static bool using_xtrabackup(MXS_MONITORED_SERVER *database, const char* server_string)
{
bool rval = false;
MYSQL_RES* result;
if (mxs_mysql_query(database->con, "SHOW VARIABLES LIKE 'wsrep_sst_method'") == 0
&& (result = mysql_store_result(database->con)) != NULL)
{
if (mysql_field_count(database->con) < 2)
{
mysql_free_result(result);
MXS_ERROR("Unexpected result for \"SHOW VARIABLES LIKE "
"'wsrep_sst_method'\". Expected 2 columns."
" MySQL Version: %s", server_string);
}
MYSQL_ROW row;
while ((row = mysql_fetch_row(result)))
{
if (row[1] && strncmp(row[1], "xtrabackup", 10) == 0)
{
rval = true;
}
}
mysql_free_result(result);
}
else
{
mon_report_query_error(database);
}
return rval;
}
/**
* get candidate master from all nodes
*
* The current available rule: get the server with MXS_MIN(node_id)
* node_id comes from 'wsrep_local_index' variable
*
* @param servers The monitored servers list
* @return The candidate master on success, NULL on failure
*/
MXS_MONITORED_SERVER *GaleraMonitor::get_candidate_master()
{
MXS_MONITORED_SERVER *moitor_servers = m_monitor->monitored_servers;
MXS_MONITORED_SERVER *candidate_master = NULL;
long min_id = -1;
int minval = INT_MAX;
int currval;
/* set min_id to the lowest value of moitor_servers->server->node_id */
while (moitor_servers)
{
if (!server_is_in_maint(moitor_servers->server) &&
(moitor_servers->pending_status & SERVER_JOINED))
{
char buf[50]; // Enough to hold most numbers
if (m_use_priority && server_get_parameter(moitor_servers->server, "priority", buf, sizeof(buf)))
{
/** The server has a priority */
if ((currval = atoi(buf)) > 0)
{
/** The priority is valid */
if (currval < minval && currval > 0)
{
minval = currval;
candidate_master = moitor_servers;
}
}
}
else if (moitor_servers->server->node_id >= 0 &&
(!m_use_priority || candidate_master == NULL))
{
// Server priorities are not in use or no candidate has been found
if (min_id < 0 || moitor_servers->server->node_id < min_id)
{
min_id = moitor_servers->server->node_id;
candidate_master = moitor_servers;
}
}
}
moitor_servers = moitor_servers->next;
}
if (!m_use_priority && !m_disableMasterFailback &&
m_root_node_as_master && min_id > 0)
{
/** The monitor couldn't find the node with wsrep_local_index of 0.
* This means that we can't connect to the root node of the cluster.
*
* If the node is down, the cluster would recalculate the index values
* and we would find it. In this case, we just can't connect to it.
*/
candidate_master = NULL;
}
return candidate_master;
}
/**
* set the master server in the cluster
*
* master could be the last one from previous monitor cycle Iis running) or
* the candidate master.
* The selection is based on the configuration option mapped to master_stickiness
* The candidate master may change over time due to
* 'wsrep_local_index' value change in the Galera Cluster
* Enabling master_stickiness will avoid master change unless a failure is spotted
*
* @param current_master Previous master server
* @param candidate_master The candidate master server accordingly to the selection rule
* @return The master node pointer (could be NULL)
*/
static MXS_MONITORED_SERVER *set_cluster_master(MXS_MONITORED_SERVER *current_master,
MXS_MONITORED_SERVER *candidate_master,
int master_stickiness)
{
/*
* if current master is not set or master_stickiness is not enable
* just return candidate_master.
*/
if (current_master == NULL || master_stickiness == 0)
{
return candidate_master;
}
else
{
/*
* if current_master is still a cluster member use it
*
*/
if ((current_master->pending_status & SERVER_JOINED) &&
(!server_is_in_maint(current_master->server)))
{
return current_master;
}
else
{
return candidate_master;
}
}
}
/**
* Set the global variable wsrep_sst_donor in the cluster
*
* The monitor user must have the privileges for setting global vars.
*
* Galera monitor fetches from each joined slave node the var 'wsrep_node_name'
* A list of nodes is automatically build and it's sorted by wsrep_local_index DESC
* or by priority ASC if use_priority option is set.
*
* The list is then added to SET GLOBAL VARIABLE wrep_sst_donor =
* The variable must be sent to all slave nodes.
*
* All slave nodes have a sorted list of nodes tht can be used as donor nodes.
*
* If there is only one node the funcion returns,
*
* @param mon The monitor handler
* @param is_cluster The number of joined nodes
*/
void GaleraMonitor::update_sst_donor_nodes(int is_cluster)
{
MXS_MONITORED_SERVER *ptr;
MYSQL_ROW row;
MYSQL_RES *result;
bool ignore_priority = true;
if (is_cluster == 1)
{
return; //Only one server in the cluster: update_sst_donor_nodes is not performed
}
unsigned int found_slaves = 0;
MXS_MONITORED_SERVER *node_list[is_cluster - 1];
/* Donor list size = DONOR_LIST_SET_VAR + n_hosts * max_host_len + n_hosts + 1 */
char *donor_list = static_cast<char*>(MXS_CALLOC(1, strlen(DONOR_LIST_SET_VAR) +
is_cluster * DONOR_NODE_NAME_MAX_LEN +
is_cluster + 1));
if (donor_list == NULL)
{
MXS_ERROR("can't execute update_sst_donor_nodes() due to memory allocation error");
return;
}
strcpy(donor_list, DONOR_LIST_SET_VAR);
ptr = m_monitor->monitored_servers;
/* Create an array of slave nodes */
while (ptr)
{
if ((ptr->pending_status & SERVER_JOINED) && (ptr->pending_status & SERVER_SLAVE))
{
node_list[found_slaves] = (MXS_MONITORED_SERVER *)ptr;
found_slaves++;
/* Check the server parameter "priority"
* If no server has "priority" set, then
* the server list will be order by default method.
*/
if (m_use_priority && server_get_parameter(ptr->server, "priority", NULL, 0))
{
ignore_priority = false;
}
}
ptr = ptr->next;
}
/* Set order type */
bool sort_order = (!ignore_priority) && (int)m_use_priority;
/* Sort the array */
qsort(node_list,
found_slaves,
sizeof(MXS_MONITORED_SERVER *),
sort_order ? compare_node_priority : compare_node_index);
/* Select nodename from each server and append it to node_list */
for (unsigned int k = 0; k < found_slaves; k++)
{
MXS_MONITORED_SERVER *ptr = node_list[k];
/* Get the Galera node name */
if (mxs_mysql_query(ptr->con, "SHOW VARIABLES LIKE 'wsrep_node_name'") == 0
&& (result = mysql_store_result(ptr->con)) != NULL)
{
if (mysql_field_count(ptr->con) < 2)
{
mysql_free_result(result);
MXS_ERROR("Unexpected result for \"SHOW VARIABLES LIKE 'wsrep_node_name'\". "
"Expected 2 columns");
return;
}
while ((row = mysql_fetch_row(result)))
{
strncat(donor_list, row[1], DONOR_NODE_NAME_MAX_LEN);
strcat(donor_list, ",");
}
mysql_free_result(result);
}
else
{
mon_report_query_error(ptr);
}
}
int donor_list_size = strlen(donor_list);
if (donor_list[donor_list_size - 1] == ',')
{
donor_list[donor_list_size - 1] = '\0';
}
strcat(donor_list, "\"");
/* Set now rep_sst_donor in each slave node */
for (unsigned int k = 0; k < found_slaves; k++)
{
MXS_MONITORED_SERVER *ptr = node_list[k];
if (mxs_mysql_query(ptr->con, donor_list) != 0)
{
mon_report_query_error(ptr);
}
}
MXS_FREE(donor_list);
}
/**
* Compare routine for slave nodes sorted by 'wsrep_local_index'
*
* The default order is DESC.
*
* Nodes with lowest 'wsrep_local_index' value
* are at the end of the list.
*
* @param a Pointer to array value
* @param b Pointer to array value
* @return A number less than, threater than or equal to 0
*/
static int compare_node_index (const void *a, const void *b)
{
const MXS_MONITORED_SERVER *s_a = *(MXS_MONITORED_SERVER * const *)a;
const MXS_MONITORED_SERVER *s_b = *(MXS_MONITORED_SERVER * const *)b;
// Order is DESC: b - a
return s_b->server->node_id - s_a->server->node_id;
}
/**
* Compare routine for slave nodes sorted by node priority
*
* The default order is DESC.
*
* Some special cases, i.e: no give priority, or 0 value
* are handled.
*
* Note: the master selection algorithm is:
* node with lowest priority value and > 0
*
* This sorting function will add master candidates
* at the end of the list.
*
* @param a Pointer to array value
* @param b Pointer to array value
* @return A number less than, threater than or equal to 0
*/
static int compare_node_priority (const void *a, const void *b)
{
const MXS_MONITORED_SERVER *s_a = *(MXS_MONITORED_SERVER * const *)a;
const MXS_MONITORED_SERVER *s_b = *(MXS_MONITORED_SERVER * const *)b;
char pri_a[50];
char pri_b[50];
bool have_a = server_get_parameter(s_a->server, "priority", pri_a, sizeof(pri_a));
bool have_b = server_get_parameter(s_b->server, "priority", pri_b, sizeof(pri_b));
/**
* Check priority parameter:
*
* Return a - b in case of issues
*/
if (!have_a && have_b)
{
MXS_DEBUG("Server %s has no given priority. It will be at the beginning of the list",
s_a->server->name);
return -(INT_MAX - 1);
}
else if (have_a && !have_b)
{
MXS_DEBUG("Server %s has no given priority. It will be at the beginning of the list",
s_b->server->name);
return INT_MAX - 1;
}
else if (!have_a && !have_b)
{
MXS_DEBUG("Servers %s and %s have no given priority. They be at the beginning of the list",
s_a->server->name,
s_b->server->name);
return 0;
}
/* The given priority is valid */
int pri_val_a = atoi(pri_a);
int pri_val_b = atoi(pri_b);
/* Return a - b in case of issues */
if ((pri_val_a < INT_MAX && pri_val_a > 0) && !(pri_val_b < INT_MAX && pri_val_b > 0))
{
return pri_val_a;
}
else if (!(pri_val_a < INT_MAX && pri_val_a > 0) && (pri_val_b < INT_MAX && pri_val_b > 0))
{
return -pri_val_b;
}
else if (!(pri_val_a < INT_MAX && pri_val_a > 0) && !(pri_val_b < INT_MAX && pri_val_b > 0))
{
return 0;
}
// The order is DESC: b -a
return pri_val_b - pri_val_a;
}
/**
* Only set the servers as joined if they are a part of the largest cluster
*/
void GaleraMonitor::set_galera_cluster()
{
int cluster_size = 0;
std::string cluster_uuid;
for (auto it = m_info.begin(); it != m_info.end(); it++)
{
if (it->second.joined && it->second.cluster_size > cluster_size)
{
// Use the UUID of the largest cluster
cluster_size = it->second.cluster_size;
cluster_uuid = it->second.cluster_uuid;
}
}
for (auto it = m_info.begin(); it != m_info.end(); it++)
{
if (it->second.joined)
{
monitor_set_pending_status(it->first, SERVER_JOINED);
}
else
{
monitor_clear_pending_status(it->first, SERVER_JOINED);
}
}
}
/**
* The module entry point routine. It is this routine that
* must populate the structure that is referred to as the
* "module object", this is a structure with the set of
* external entry points for this module.
*
* @return The module object
*/
extern "C" MXS_MODULE* MXS_CREATE_MODULE()
{
MXS_NOTICE("Initialise the MySQL Galera Monitor module.");
static MXS_MODULE info =
{
MXS_MODULE_API_MONITOR,
MXS_MODULE_GA,
MXS_MONITOR_VERSION,
"A Galera cluster monitor",
"V2.0.0",
MXS_NO_MODULE_CAPABILITIES,
&maxscale::MonitorApi<GaleraMonitor>::s_api,
NULL, /* Process init. */
NULL, /* Process finish. */
NULL, /* Thread init. */
NULL, /* Thread finish. */
{
{"disable_master_failback", MXS_MODULE_PARAM_BOOL, "false"},
{"available_when_donor", MXS_MODULE_PARAM_BOOL, "false"},
{"disable_master_role_setting", MXS_MODULE_PARAM_BOOL, "false"},
{"root_node_as_master", MXS_MODULE_PARAM_BOOL, "false"},
{"use_priority", MXS_MODULE_PARAM_BOOL, "false"},
{"set_donor_nodes", MXS_MODULE_PARAM_BOOL, "false"},
{MXS_END_MODULE_PARAMS}
}
};
return &info;
}
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