I'm new to k8s, using docker-mac-desktop k8s test spring boot app.

I'm can connect success when spring boot in local connect mysql.

transform to docker k8s can not connected.

error is:

com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure
at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) ~[mysql-connector-java-8.0.19.jar!/:8.0.19]
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-java-8.0.19.jar!/:8.0.19]
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836) ~[mysql-connector-java-8.0.19.jar!/:8.0.19]
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456) ~[mysql-connector-java-8.0.19.jar!/:8.0.19]
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246) ~[mysql-connector-java-8.0.19.jar!/:8.0.19]
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:197) ~[mysql-connector-java-8.0.19.jar!/:8.0.19]

is is local listening port:

redis-ser  2008    f    6u  IPv4 0x135c39363e412e7f      0t0  TCP 127.0.0.1:6379 (LISTEN)
kubectl    2909    f    7u  IPv4 0x135c39365cf8a6ff      0t0  TCP 127.0.0.1:8500 (LISTEN)
kubectl    2909    f    8u  IPv6 0x135c39365e7fb2cf      0t0  TCP [::1]:8500 (LISTEN)
mysqld     4091    f   28u  IPv4 0x135c39364db92abf      0t0  TCP 127.0.0.1:3306 (LISTEN)
mysqld     4091    f   32u  IPv4 0x135c39364dc7e6ff      0t0  TCP 127.0.0.1:33060 (LISTEN)
com.docke 41823    f   20u  IPv4 0x135c39365b9a4d1f      0t0  TCP 127.0.0.1:6443 (LISTEN)
com.docke 41823    f   25u  IPv6 0x135c39365e7f9a4f      0t0  TCP *:32003 (LISTEN)
com.docke 41926    f    8u  IPv4 0x135c393660b3785f      0t0  TCP 127.0.0.1:60701 (LISTEN)

spring boot database config:

spring:
datasource:
url: jdbc:mysql://mysqldb:3306/foo
# mysqldb.default.svc.cluster.local tried
#
driver-class-name: com.mysql.cj.jdbc.Driver
username: f

spring boot pod.yml:

apiVersion: v1
kind: Pod
metadata:
  name: user-service
  labels:
    app: user-service
spec:
  containers:
    - name: user-service
      image: user_service:v1

map database ref: https://cloud.google.com/blog/products/gcp/kubernetes-best-practices-mapping-external-services

mysql_svc.yml:

apiVersion: v1
kind: Service
metadata:
name: mysqldb
spec:
ports:
    - port: 3306
    targetPort: 3306

---
kind: Endpoints
apiVersion: v1
metadata:
name: mysqldb
subsets:
- addresses:
    - ip: 192.168.0.101
    ports:
    - port: 3306

while the ip is come from ifconfig

en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
    options=400<CHANNEL_IO>
    inet6 fe80::c2c:cc27:8121:fbac%en0 prefixlen 64 secured scopeid 0x5 
    inet 192.168.0.101 netmask 0xffffff00 broadcast 192.168.0.255
    nd6 options=201<PERFORMNUD,DAD>
    media: autoselect
    status: active

how can connect from k8s pod connect localhost database? :)