Added more InnoDB metric to MySQL plugin (influxdata#2179)

plugins/inputs/mysql/README.md

@@ -9,6 +9,7 @@ This plugin gathers the statistic data from MySQL server
 * Process list
 * User Statistics
 * Info schema auto increment columns
+* InnoDB metrics
 * Table I/O waits
 * Index I/O waits
 * Perf Schema table lock waits
@@ -51,6 +52,9 @@ This plugin gathers the statistic data from MySQL server
   ## gather auto_increment columns and max values from information schema
   gather_info_schema_auto_inc               = true
   #
+  ## gather metrics from INFORMATION_SCHEMA.INNODB_METRICS
+  gather_innodb_metrics                     = true
+  #
   ## gather metrics from SHOW SLAVE STATUS command output
   gather_slave_status                       = true
   #
@@ -141,6 +145,7 @@ and process. It has following fields:
 for them. It has following fields:
     * auto_increment_column(int, number)
     * auto_increment_column_max(int, number)
+* InnoDB metrics - all metrics of information_schema.INNODB_METRICS with a status "enabled"
 * Perf table lock waits - gathers total number and time for SQL and external
 lock waits events for each table and operation. It has following fields.
 The unit of fields varies by the tags.

plugins/inputs/mysql/mysql.go

@@ -25,6 +25,7 @@ type Mysql struct {
 	GatherProcessList                   bool     `toml:"gather_process_list"`
 	GatherUserStatistics                bool     `toml:"gather_user_statistics"`
 	GatherInfoSchemaAutoInc             bool     `toml:"gather_info_schema_auto_inc"`
+	GatherInnoDBMetrics                 bool     `toml:"gather_innodb_metrics"`
 	GatherSlaveStatus                   bool     `toml:"gather_slave_status"`
 	GatherBinaryLogs                    bool     `toml:"gather_binary_logs"`
 	GatherTableIOWaits                  bool     `toml:"gather_table_io_waits"`
@@ -67,6 +68,9 @@ var sampleConfig = `
   ## gather auto_increment columns and max values from information schema
   gather_info_schema_auto_inc               = true
   #
+  ## gather metrics from INFORMATION_SCHEMA.INNODB_METRICS
+  gather_innodb_metrics                     = true
+  #
   ## gather metrics from SHOW SLAVE STATUS command output
   gather_slave_status                       = true
   #
@@ -435,6 +439,11 @@ const (
           FROM information_schema.tables t
           JOIN information_schema.columns c USING (table_schema,table_name)
           WHERE c.extra = 'auto_increment' AND t.auto_increment IS NOT NULL
+    `
+	innoDBMetricsQuery = `
+        SELECT NAME, COUNT
+        FROM information_schema.INNODB_METRICS
+        WHERE status='enabled'
     `
 	perfTableIOWaitsQuery = `
         SELECT OBJECT_SCHEMA, OBJECT_NAME, COUNT_FETCH, COUNT_INSERT, COUNT_UPDATE, COUNT_DELETE,
@@ -610,6 +619,13 @@ func (m *Mysql) gatherServer(serv string, acc telegraf.Accumulator) error {
 		}
 	}
 
+	if m.GatherInnoDBMetrics {
+		err = m.gatherInnoDBMetrics(db, serv, acc)
+		if err != nil {
+			return err
+		}
+	}
+
 	if m.GatherTableIOWaits {
 		err = m.gatherPerfTableIOWaits(db, serv, acc)
 		if err != nil {
@@ -1244,6 +1260,45 @@ func (m *Mysql) gatherInfoSchemaAutoIncStatuses(db *sql.DB, serv string, acc tel
 	return nil
 }
 
+// gatherInnoDBMetrics can be used to fetch enabled metrics from
+// information_schema.INNODB_METRICS
+func (m *Mysql) gatherInnoDBMetrics(db *sql.DB, serv string, acc telegraf.Accumulator) error {
+	// run query
+	rows, err := db.Query(innoDBMetricsQuery)
+	if err != nil {
+		return err
+	}
+	defer rows.Close()
+
+	var key string
+	var val sql.RawBytes
+
+	// parse DSN and save server tag
+	servtag := getDSNTag(serv)
+	tags := map[string]string{"server": servtag}
+	fields := make(map[string]interface{})
+	for rows.Next() {
+		if err := rows.Scan(&key, &val); err != nil {
+			return err
+		}
+		key = strings.ToLower(key)
+		// parse value, if it is numeric then save, otherwise ignore
+		if floatVal, ok := parseValue(val); ok {
+			fields[key] = floatVal
+		}
+		// Send 20 fields at a time
+		if len(fields) >= 20 {
+			acc.AddFields("mysql_innodb", fields, tags)
+			fields = make(map[string]interface{})
+		}
+	}
+	// Send any remaining fields
+	if len(fields) > 0 {
+		acc.AddFields("mysql_innodb", fields, tags)
+	}
+	return nil
+}
+
 // gatherPerfTableLockWaits can be used to get
 // the total number and time for SQL and external lock wait events
 // for each table and operation