Allow to collect multiple instances per host

(as inspired by https://github.com/powdahound/redis-collectd-plugin/blob/master/redis_info.py)

Author: Jan Kunzmann

README.md

@@ -32,11 +32,14 @@ You should then configure the MySQL plugin:
 			Port 3306 (default: 3306)
 			User "root" (default: root)
 			Password "xxxx" (default: empty)
+      Instance "" (default: empty instance identifier)
 			HeartbeatTable "percona.heartbeat" (if using pt-heartbeat to track slave lag)
 			Verbose false (default: false)
 		</Module>
 	</Plugin>
 
+Repeat the "Module" section for multiple instances
+
 ## Metrics
 
 ### MySQL Status

mysql.py

@@ -6,7 +6,7 @@
 # all of the legacy compatibility, and favors metrics from SHOW GLOBAL STATUS
 # as opposed to SHOW ENGINE INNODB STATUS where possible.
 #
-# Configuration:
+# Configuration (repeat Module section for multiple instances):
 #  Import mysql
 #  <Module mysql>
 #   Host localhost
@@ -29,16 +29,13 @@
 import collectd
 import re
 import MySQLdb
+import copy
 
-MYSQL_CONFIG = {
-	'Host':           'localhost',
-	'Port':           3306,
-	'User':           'root',
-	'Password':       '',
-	'HeartbeatTable': '',
-	'Verbose':        False,
-	'Instance':       '',
-}
+
+# Verbose logging on/off. Override in config by specifying 'Verbose'.
+VERBOSE_LOGGING = False
+
+CONFIGS = []
 
 MYSQL_STATUS_VARS = {
 	'Aborted_clients': 'counter',
@@ -303,12 +300,12 @@
 	},
 }
 
-def get_mysql_conn():
+def get_mysql_conn(conf):
 	return MySQLdb.connect(
-		host=MYSQL_CONFIG['Host'],
-		port=MYSQL_CONFIG['Port'],
-		user=MYSQL_CONFIG['User'],
-		passwd=MYSQL_CONFIG['Password']
+		host=conf['host'],
+		port=conf['port'],
+		user=conf['user'],
+		passwd=conf['password']
 	)
 
 def mysql_query(conn, query):
@@ -350,7 +347,7 @@ def fetch_mysql_master_stats(conn):
 
 	return stats
 
-def fetch_mysql_slave_stats(conn):
+def fetch_mysql_slave_stats(conf, conn):
 	result    = mysql_query(conn, 'SHOW SLAVE STATUS')
 	slave_row = result.fetchone()
 	if slave_row is None:
@@ -362,12 +359,12 @@ def fetch_mysql_slave_stats(conn):
 		'slave_lag':       slave_row['Seconds_Behind_Master'] if slave_row['Seconds_Behind_Master'] != None else 0,
 	}
 
-	if MYSQL_CONFIG['HeartbeatTable']:
+	if conf['heartbeattable']:
 		query = """
 			SELECT MAX(UNIX_TIMESTAMP() - UNIX_TIMESTAMP(ts)) AS delay
 			FROM %s
 			WHERE server_id = %s
-		""" % (MYSQL_CONFIG['HeartbeatTable'], slave_row['Master_Server_Id'])
+		""" % (conf['heartbeattable'], slave_row['Master_Server_Id'])
 		result = mysql_query(conn, query)
 		row    = result.fetchone()
 		if 'delay' in row and row['delay'] != None:
@@ -471,11 +468,10 @@ def fetch_innodb_stats(conn):
 	return stats
 
 def log_verbose(msg):
-	if MYSQL_CONFIG['Verbose'] == False:
-		return
-	collectd.info('mysql plugin: %s' % msg)
+	if VERBOSE_LOGGING:
+		collectd.info('mysql plugin: %s' % msg)
 
-def dispatch_value(prefix, key, value, type, type_instance=None):
+def dispatch_value(instance, prefix, key, value, type, type_instance=None):
 	if not type_instance:
 		type_instance = key
 
@@ -484,26 +480,61 @@ def dispatch_value(prefix, key, value, type, type_instance=None):
 		return
 	value = int(value) # safety check
 
-	val                 = collectd.Values(plugin='mysql', plugin_instance=prefix)
-	val.plugin          = 'mysql.%s' % MYSQL_CONFIG['Instance']
-	val.plugin_instance = prefix
+	if instance is None:
+		plugin = 'mysql'
+	else:
+		plugin = 'mysql.%s' % instance
+	val                 = collectd.Values(plugin=plugin, plugin_instance=prefix)
 	val.type            = type
 	val.type_instance   = type_instance
 	val.values          = [value]
 	val.dispatch()
 
 def configure_callback(conf):
-	global MYSQL_CONFIG
+	instance = None
+	host = 'localhost'
+	port = 3306
+	user = 'root'
+	password = ''
+	heartbeattable = ''
+	verbose = False
+
 	for node in conf.children:
-		if node.key in MYSQL_CONFIG:
-			MYSQL_CONFIG[node.key] = node.values[0]
+		key = node.key.lower()
+		val = node.values[0]
+		if key == 'instance':
+			instance = val
+		elif key == 'host':
+			host = val
+		elif key == 'port':
+			port = int(val)
+		elif key == 'user':
+			user = val
+		elif key == 'password':
+			password = val
+		elif key == 'heartbeattable':
+			heartbeattable = val
+		elif key == 'verbose':
+			global VERBOSE_LOGGING
+			VERBOSE_LOGGING = bool(val) or VERBOSE_LOGGING
+		else:
+			collectd.warning('mysql plugin: Unknown config key: %s.' % key)
 
-	MYSQL_CONFIG['Port']    = int(MYSQL_CONFIG['Port'])
-	MYSQL_CONFIG['Verbose'] = bool(MYSQL_CONFIG['Verbose'])
+	log_verbose('Configured with host=%s, port=%s, instance name=%s, user=%s' % ( host, port, instance, user))
 
-def read_callback():
+	mysql_config = {
+		'instance': instance,
+		'host': host,
+		'port': port,
+		'user': user,
+		'password': password,
+		'heartbeattable': heartbeattable
+	}
+	CONFIGS.append(mysql_config)
+
+def get_metrics(conf):
 	global MYSQL_STATUS_VARS
-	conn = get_mysql_conn()
+	conn = get_mysql_conn(conf)
 
 	mysql_status = fetch_mysql_status(conn)
 	for key in mysql_status:
@@ -519,33 +550,37 @@ def read_callback():
 		else:
 			continue
 
-		dispatch_value('status', key, mysql_status[key], ds_type)
+		dispatch_value(conf['instance'], 'status', key, mysql_status[key], ds_type)
 
 	mysql_variables = fetch_mysql_variables(conn)
 	for key in mysql_variables:
-		dispatch_value('variables', key, mysql_variables[key], 'gauge')
+		dispatch_value(conf['instance'], 'variables', key, mysql_variables[key], 'gauge')
 
 	mysql_master_status = fetch_mysql_master_stats(conn)
 	for key in mysql_master_status:
-		dispatch_value('master', key, mysql_master_status[key], 'gauge')
+		dispatch_value(conf['instance'], 'master', key, mysql_master_status[key], 'gauge')
 
 	mysql_states = fetch_mysql_process_states(conn)
 	for key in mysql_states:
-		dispatch_value('state', key, mysql_states[key], 'gauge')
+		dispatch_value(conf['instance'], 'state', key, mysql_states[key], 'gauge')
 
-	slave_status = fetch_mysql_slave_stats(conn)
+	slave_status = fetch_mysql_slave_stats(conf, conn)
 	for key in slave_status:
-		dispatch_value('slave', key, slave_status[key], 'gauge')
+		dispatch_value(conf['instance'], 'slave', key, slave_status[key], 'gauge')
 
 	response_times = fetch_mysql_response_times(conn)
 	for key in response_times:
-		dispatch_value('response_time_total', str(key), response_times[key]['total'], 'counter')
-		dispatch_value('response_time_count', str(key), response_times[key]['count'], 'counter')
+		dispatch_value(conf['instance'], 'response_time_total', str(key), response_times[key]['total'], 'counter')
+		dispatch_value(conf['instance'], 'response_time_count', str(key), response_times[key]['count'], 'counter')
 
 	innodb_status = fetch_innodb_stats(conn)
 	for key in MYSQL_INNODB_STATUS_VARS:
 		if key not in innodb_status: continue
-		dispatch_value('innodb', key, innodb_status[key], MYSQL_INNODB_STATUS_VARS[key])
+		dispatch_value(conf['instance'], 'innodb', key, innodb_status[key], MYSQL_INNODB_STATUS_VARS[key])
+
+def read_callback():
+	for conf in CONFIGS:
+		get_metrics(conf)
 
 collectd.register_read(read_callback)
 collectd.register_config(configure_callback)