Set metrics exporter port based on extra_port

Author: stankevich

Changelog.md

@@ -59,10 +59,16 @@ adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
  * Change default resource requests/limits for `sidecar` container: requested=10m/32Mi, limit=the same as `.spec.podSpec.resources.limit`
  * Change default resource requests/limits for `exporter` container: requested=10m/32Mi, limit=100m/128Mi
  * Change default resource requests/limits for `heartbeat` container: requested=10m/32Mi, limit=100m/64Mi
+ * If [`extra_port`](https://www.percona.com/doc/percona-server/5.7/performance/threadpool.html#extra_port)
+   is defined in the cluster spec, metrics exporter will use it to connect to MySQL providing that
+   [`extra_max_connections`](https://www.percona.com/doc/percona-server/5.7/performance/threadpool.html#extra_max_connections)
+   is larger than the default `1`. If MySQL server runs out of available connections, using `extra_port`
+   allows the exporter to continue collecting MySQL metrics.
 ### Removed
 ### Fixed
  * Update and fix e2e tests
  * Fix double date string in backup path
+ * Fix double date string in bakup path
  * Copy the nodeSelector as-is in the statefulset (fixes #454)
  * Fix flakines in ReadOnly cluster condition (fixes #434)
  * Fix rounding in computing `innodb-buffer-pool-size` (fixes #501)

pkg/controller/mysqlcluster/internal/syncer/statefullset.go

@@ -290,7 +290,7 @@ func (s *sfsSyncer) getEnvFor(name string) []core.EnvVar {
 		env = append(env, s.envVarFromSecret(sctOpName, "PASSWORD", "METRICS_EXPORTER_PASSWORD", false))
 		env = append(env, core.EnvVar{
 			Name:  "DATA_SOURCE_NAME",
-			Value: fmt.Sprintf("$(USER):$(PASSWORD)@(127.0.0.1:%d)/", MysqlPort),
+			Value: fmt.Sprintf("$(USER):$(PASSWORD)@(127.0.0.1:%d)/", s.cluster.ExporterDataSourcePort()),
 		})
 	case containerMySQLInitName:
 		// set MySQL init only flag for init container

pkg/internal/mysqlcluster/mysqlcluster.go

@@ -18,9 +18,10 @@ package mysqlcluster
 
 import (
 	"fmt"
-	"github.com/presslabs/mysql-operator/pkg/options"
 	"strings"
 
+	"github.com/presslabs/mysql-operator/pkg/options"
+
 	"github.com/blang/semver"
 	core "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/labels"
@@ -230,3 +231,24 @@ func (c *MysqlCluster) ShouldHaveInitContainerForMysql() bool {
 func (c *MysqlCluster) String() string {
 	return fmt.Sprintf("%s/%s", c.Namespace, c.Name)
 }
+
+// ExporterDataSourcePort returns a MySQL port mysqld-exporter should connect to.
+// Returns `extra_port` if defined in the cluster spec and if `extra_max_connections`
+// is defined and larger than the default 1. Otherwise, returns the default MySQL port.
+// https://www.percona.com/doc/percona-server/5.7/performance/threadpool.html#extra_port
+func (c *MysqlCluster) ExporterDataSourcePort() int {
+	extraPortSettings := []string{"extra_port", "extra-port"}
+	extraMaxConnectionsSettings := []string{"extra_max_connections", "extra-max-connections"}
+
+	for _, setting := range extraPortSettings {
+		if port, ok := c.Spec.MysqlConf[setting]; ok {
+			for _, setting := range extraMaxConnectionsSettings {
+				if conns, ok := c.Spec.MysqlConf[setting]; ok && conns.IntValue() > 1 {
+					return port.IntValue()
+				}
+			}
+		}
+	}
+
+	return constants.MysqlPort
+}