[ko] Upgrade mysql image version used by Single-Instance Stateful tutorial

Author: serut

content/ko/docs/tasks/run-application/run-single-instance-stateful-application.md

@@ -80,7 +80,7 @@ MySQL을 실행하고 퍼시스턴트볼륨클레임을 참조하는 디플로
           Labels:       app=mysql
           Containers:
            mysql:
-            Image:      mysql:5.6
+            Image:      mysql:9
             Port:       3306/TCP
             Environment:
               MYSQL_ROOT_PASSWORD:      password
@@ -141,7 +141,7 @@ MySQL을 실행하고 퍼시스턴트볼륨클레임을 참조하는 디플로
 서버에 접속하기 위하여 MySQL 클라이언트를 실행한다.
 
 ```
-kubectl run -it --rm --image=mysql:5.6 --restart=Never mysql-client -- mysql -h mysql -ppassword
+kubectl run -it --rm --image=mysql:9 --restart=Never mysql-client -- mysql -h mysql -ppassword
 ```
 
 이 명령어는 MySQL 클라이언트를 실행하는 파드를 클러스터에 생성하고, 

content/ko/examples/application/mysql/mysql-deployment.yaml

@@ -25,7 +25,7 @@ spec:
         app: mysql
     spec:
       containers:
-      - image: mysql:5.6
+      - image: mysql:9
         name: mysql
         env:
           # Use secret in real usage

content/ko/examples/application/wordpress/mysql-deployment.yaml

@@ -45,14 +45,23 @@ spec:
         tier: mysql
     spec:
       containers:
-      - image: mysql:5.6
+      - image: mysql:8.0
         name: mysql
         env:
         - name: MYSQL_ROOT_PASSWORD
           valueFrom:
             secretKeyRef:
               name: mysql-pass
               key: password
+        - name: MYSQL_DATABASE
+          value: wordpress
+        - name: MYSQL_USER
+          value: wordpress
+        - name: MYSQL_PASSWORD
+          valueFrom:
+            secretKeyRef:
+              name: mysql-pass
+              key: password
         ports:
         - containerPort: 3306
           name: mysql