collect mysql global variables

inputs/mysql/global_variables.go

@@ -2,10 +2,110 @@ package mysql
 
 import (
 	"database/sql"
+	"log"
+	"regexp"
+	"strconv"
+	"strings"
 
+	"flashcat.cloud/categraf/inputs"
+	"flashcat.cloud/categraf/pkg/tagx"
 	"github.com/toolkits/pkg/container/list"
 )
 
 func (m *MySQL) gatherGlobalVariables(slist *list.SafeList, ins *Instance, db *sql.DB, globalTags map[string]string) {
+	rows, err := db.Query(SQL_GLOBAL_VARIABLES)
+	if err != nil {
+		log.Println("E! failed to query global variables:", err)
+		return
+	}
 
+	defer rows.Close()
+
+	var (
+		key       string
+		val       sql.RawBytes
+		tags      = tagx.Copy(globalTags)
+		textItems = map[string]string{
+			"innodb_version":         "",
+			"version":                "",
+			"version_comment":        "",
+			"wsrep_cluster_name":     "",
+			"wsrep_provider_options": "",
+			"tx_isolation":           "",
+			"transaction_isolation":  "",
+		}
+	)
+
+	for rows.Next() {
+		if err = rows.Scan(&key, &val); err != nil {
+			continue
+		}
+
+		// key to lower
+		key = strings.ToLower(key)
+
+		// collect some string fields
+		if _, has := textItems[key]; has {
+			textItems[key] = string(val)
+			continue
+		}
+
+		// collect float fields
+		if _, has := ins.validMetrics[key]; !has {
+			continue
+		}
+
+		if floatVal, ok := parseStatus(val); ok {
+			slist.PushFront(inputs.NewSample("global_variables_"+key, floatVal, tags))
+			continue
+		}
+	}
+
+	slist.PushFront(inputs.NewSample("version_info", 1, tags, map[string]string{
+		"version":         textItems["version"],
+		"innodb_version":  textItems["innodb_version"],
+		"version_comment": textItems["version_comment"],
+	}))
+
+	// mysql_galera_variables_info metric.
+	// PXC/Galera variables information.
+	if textItems["wsrep_cluster_name"] != "" {
+		slist.PushFront(inputs.NewSample("galera_variables_info", 1, tags, map[string]string{
+			"wsrep_cluster_name": textItems["wsrep_cluster_name"],
+		}))
+	}
+
+	// mysql_galera_gcache_size_bytes metric.
+	if textItems["wsrep_provider_options"] != "" {
+		slist.PushFront(inputs.NewSample("galera_gcache_size_bytes", parseWsrepProviderOptions(textItems["wsrep_provider_options"]), tags))
+	}
+
+	if textItems["transaction_isolation"] != "" || textItems["tx_isolation"] != "" {
+		level := textItems["transaction_isolation"]
+		if level == "" {
+			level = textItems["tx_isolation"]
+		}
+
+		slist.PushFront(inputs.NewSample("transaction_isolation", 1, tags, map[string]string{"level": level}))
+	}
+}
+
+// parseWsrepProviderOptions parse wsrep_provider_options to get gcache.size in bytes.
+func parseWsrepProviderOptions(opts string) float64 {
+	var val float64
+	r, _ := regexp.Compile(`gcache.size = (\d+)([MG]?);`)
+	data := r.FindStringSubmatch(opts)
+	if data == nil {
+		return 0
+	}
+
+	val, _ = strconv.ParseFloat(data[1], 64)
+	switch data[2] {
+	case "M":
+		val = val * 1024 * 1024
+	case "G":
+		val = val * 1024 * 1024 * 1024
+	}
+
+	return val
 }

inputs/mysql/queries.go

@@ -7,6 +7,8 @@ package mysql
 const (
 	SQL_GLOBAL_STATUS = `SHOW /*!50002 GLOBAL */ STATUS`
 
+	SQL_GLOBAL_VARIABLES = `SHOW GLOBAL VARIABLES`
+
 	SQL_95TH_PERCENTILE = `SELECT avg_us, ro as percentile FROM
 (SELECT avg_us, @rownum := @rownum + 1 as ro FROM
     (SELECT ROUND(avg_timer_wait / 1000000) as avg_us