Check for errors in user stats & process list

closes #2414

CHANGELOG.md

@@ -63,6 +63,7 @@ be deprecated eventually.
 - [#2282](https://github.com/influxdata/telegraf/issues/2282): Reloading telegraf freezes prometheus output.
 - [#2390](https://github.com/influxdata/telegraf/issues/2390): Empty tag value causes error on InfluxDB output.
 - [#2380](https://github.com/influxdata/telegraf/issues/2380): buffer_size field value is negative number from "internal" plugin.
+- [#2414](https://github.com/influxdata/telegraf/issues/2414): Missing error handling in the MySQL plugin leads to segmentation violation.
 
 ## v1.2.1 [2017-02-01]
 

plugins/inputs/mysql/mysql.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"database/sql"
 	"fmt"
+	"log"
 	"strconv"
 	"strings"
 	"sync"
@@ -904,7 +905,9 @@ func (m *Mysql) gatherGlobalStatuses(db *sql.DB, serv string, acc telegraf.Accum
 	// gather connection metrics from processlist for each user
 	if m.GatherProcessList {
 		conn_rows, err := db.Query("SELECT user, sum(1) FROM INFORMATION_SCHEMA.PROCESSLIST GROUP BY user")
-
+		if err != nil {
+			log.Printf("E! MySQL Error gathering process list: %s", err)
+		} else {
 			for conn_rows.Next() {
 				var user string
 				var connections int64
@@ -924,11 +927,14 @@ func (m *Mysql) gatherGlobalStatuses(db *sql.DB, serv string, acc telegraf.Accum
 				acc.AddFields("mysql_users", fields, tags)
 			}
 		}
+	}
 
 	// gather connection metrics from user_statistics for each user
 	if m.GatherUserStatistics {
 		conn_rows, err := db.Query("select user, total_connections, concurrent_connections, connected_time, busy_time, cpu_time, bytes_received, bytes_sent, binlog_bytes_written, rows_fetched, rows_updated, table_rows_read, select_commands, update_commands, other_commands, commit_transactions, rollback_transactions, denied_connections, lost_connections, access_denied, empty_queries, total_ssl_connections FROM INFORMATION_SCHEMA.USER_STATISTICS GROUP BY user")
-
+		if err != nil {
+			log.Printf("E! MySQL Error gathering user stats: %s", err)
+		} else {
 			for conn_rows.Next() {
 				var user string
 				var total_connections int64
@@ -992,6 +998,7 @@ func (m *Mysql) gatherGlobalStatuses(db *sql.DB, serv string, acc telegraf.Accum
 				acc.AddFields("mysql_user_stats", fields, tags)
 			}
 		}
+	}
 
 	return nil
 }