Erro ao dockerizar o microservice

Programação Java
,
#1

Pessoal, estou dando meus primeiros passos com docker e microservices e estou enfrentando um problema de estabelecer uma conexão entre o serviço e o banco de dados. Os demais serviços que foram dockerizados estão funcionando normalmente. O problema está com o serviço "buscar-cep-service" que não consegue estabelecer uma conexão com o banco de dados.

dockerfile:

FROM openjdk:17-jdk-slim
ARG JAR_FILE=02-buscar-cep-service/target/*.jar
COPY ${JAR_FILE} app.jar
RUN bash -c 'touch /app.jar'
ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app.jar"]

buscar-cep-service (serviço que está dando problema)

buscar-cep-service:
    image: henriquedev/buscar-cep-service
    build:
      context: .
      dockerfile: 02-buscar-cep-service/Dockerfile
    environment:
      TZ: America/Sao_Paulo
      EUREKA.CLIENT.SERVICEURL.DEFAULTZONE: http://eureka-server:8761/eureka
      SPRING.ZIPKIN.BASEURL: http://zipkin-server:9411/
      SPRING.DATASOURCE.URL: jdbc:mysql://cep-db:3309/cidades?useSSL=false&serverTimezone=UTC&enabledTLSProtocols=TLSv1.2
      SPRING.DATASOURCE.USERNAME: root
      SPRING.DATASOURCE.PASSWORD: henrique123
      SPRING.FLYWAY.URL: jdbc:mysql://cep-db:3309/cidades?useSSL=false&serverTimezone=UTC&enabledTLSProtocols=TLSv1.2
      SPRING.FLYWAY.USER: root
      SPRING.FLYWAY.PASSWORD: henrique123
    ports:
      - 8000:8000
    depends_on:
      - eureka-server
      - cep-db
    networks:
      - henrique-service

docker-compose.yml

version: '3.4'

services:
  eureka-server:
    image: henriquedev/eureka-server:0.0.1-SNAPSHOT
    ports:
      - 8761:8761
    networks:
     - henrique-service
  cep-db:
    image: mysql:5.7.22
    command: --default-authentication-plugin=mysql_native_password
    restart: always
    environment:
      TZ: America/Sao_Paulo
      MYSQL_ROOT_PASSWORD: henrique123
      MYSQL_USER: root
      MYSQL_PASSWORD: henrique123
      MYSQL_DATABASE: cidades
      MYSQL_ROOT_HOST: '%'
      MYSQL_TCP_PORT: 3309
    ports:
      - 3309:3309
    expose:
      - 3309
  zipkin-server:
    image: openzipkin/zipkin:2.23.16
    ports:
      - 9411:9411
    networks:
     - henrique-service
  api-gateway:
    image: henriquedev/api-gateway:0.0.1-SNAPSHOT
    ports:
      - 8765:8765
    depends_on:
      - eureka-server
    environment:
      EUREKA.CLIENT.SERVICEURL.DEFAULTZONE: http://eureka-server:8761/eureka
      SPRING.ZIPKIN.BASEURL: htt://zipkin-server:9411/
    networks:
     - henrique-service
  buscar-cep-service:
    image: henriquedev/buscar-cep-service
    build:
      context: .
      dockerfile: 02-buscar-cep-service/Dockerfile
    environment:
      TZ: America/Sao_Paulo
      EUREKA.CLIENT.SERVICEURL.DEFAULTZONE: http://eureka-server:8761/eureka
      SPRING.ZIPKIN.BASEURL: http://zipkin-server:9411/
      SPRING.DATASOURCE.URL: jdbc:mysql://cep-db:3309/cidades?useSSL=false&serverTimezone=UTC&enabledTLSProtocols=TLSv1.2
      SPRING.DATASOURCE.USERNAME: root
      SPRING.DATASOURCE.PASSWORD: henrique123
      SPRING.FLYWAY.URL: jdbc:mysql://cep-db:3309/cidades?useSSL=false&serverTimezone=UTC&enabledTLSProtocols=TLSv1.2
      SPRING.FLYWAY.USER: root
      SPRING.FLYWAY.PASSWORD: henrique123
    ports:
      - 8000:8000
    depends_on:
      - eureka-server
      - cep-db
    networks:
      - henrique-service
networks:
  henrique-service:
    driver: bridge

pilha de erro do buscar-cep-service

`----------------------------------------------------`

`SQL State  : 08S01`

`Error Code : 0`

`Message    : Communications link failure`

``

`The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.`

``

`at org.flywaydb.core.internal.jdbc.JdbcUtils.openConnection(JdbcUtils.java:67) ~[flyway-core-8.0.5.jar!/:na]`

`at org.flywaydb.core.internal.jdbc.JdbcConnectionFactory.<init>(JdbcConnectionFactory.java:74) ~[flyway-core-8.0.5.jar!/:na]`

`at org.flywaydb.core.FlywayExecutor.execute(FlywayExecutor.java:143) ~[flyway-core-8.0.5.jar!/:na]`

`at org.flywaydb.core.Flyway.migrate(Flyway.java:124) ~[flyway-core-8.0.5.jar!/:na]`

`at org.springframework.boot.autoconfigure.flyway.FlywayMigrationInitializer.afterPropertiesSet(FlywayMigrationInitializer.java:66) ~[spring-boot-autoconfigure-2.6.3.jar!/:2.6.3]`

`at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1863) ~[spring-beans-5.3.15.jar!/:5.3.15]`

`at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1800) ~[spring-beans-5.3.15.jar!/:5.3.15]`

`... 26 common frames omitted`

`Caused by: com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure`

``

`The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.`

`at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) ~[mysql-connector-java-8.0.28.jar!/:8.0.28]`

`at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-java-8.0.28.jar!/:8.0.28]`

`at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:829) ~[mysql-connector-java-8.0.28.jar!/:8.0.28]`

`at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:449) ~[mysql-connector-java-8.0.28.jar!/:8.0.28]`

`at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:242) ~[mysql-connector-java-8.0.28.jar!/:8.0.28]`

`at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198) ~[mysql-connector-java-8.0.28.jar!/:8.0.28]`

`at org.springframework.jdbc.datasource.SimpleDriverDataSource.getConnectionFromDriver(SimpleDriverDataSource.java:144) ~[spring-jdbc-5.3.15.jar!/:5.3.15]`

`at org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnectionFromDriver(AbstractDriverBasedDataSource.java:205) ~[spring-jdbc-5.3.15.jar!/:5.3.15]`

`at org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnection(AbstractDriverBasedDataSource.java:169) ~[spring-jdbc-5.3.15.jar!/:5.3.15]`

`at org.flywaydb.core.internal.jdbc.JdbcUtils.openConnection(JdbcUtils.java:52) ~[flyway-core-8.0.5.jar!/:na]`

`... 32 common frames omitted`

`Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure`

``

`The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.`

`at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:na]`

`at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:77) ~[na:na]`

`at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:na]`

`at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499) ~[na:na]`

`at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480) ~[na:na]`

`at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) ~[mysql-connector-java-8.0.28.jar!/:8.0.28]`

`at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105) ~[mysql-connector-java-8.0.28.jar!/:8.0.28]`

`at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151) ~[mysql-connector-java-8.0.28.jar!/:8.0.28]`

`at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167) ~[mysql-connector-java-8.0.28.jar!/:8.0.28]`

`at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:89) ~[mysql-connector-java-8.0.28.jar!/:8.0.28]`

`at com.mysql.cj.NativeSession.connect(NativeSession.java:120) ~[mysql-connector-java-8.0.28.jar!/:8.0.28]`

`at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:949) ~[mysql-connector-java-8.0.28.jar!/:8.0.28]`

`at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:819) ~[mysql-connector-java-8.0.28.jar!/:8.0.28]`

`... 39 common frames omitted`

`Caused by: java.net.UnknownHostException: cep-db: Temporary failure in name resolution`

`at java.base/java.net.Inet4AddressImpl.lookupAllHostAddr(Native Method) ~[na:na]`

`at java.base/java.net.InetAddress$PlatformNameService.lookupAllHostAddr(InetAddress.java:933) ~[na:na]`

`at java.base/java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1519) ~[na:na]`

`at java.base/java.net.InetAddress$NameServiceAddresses.get(InetAddress.java:852) ~[na:na]`

`at java.base/java.net.InetAddress.getAllByName0(InetAddress.java:1509) ~[na:na]`

`at java.base/java.net.InetAddress.getAllByName(InetAddress.java:1367) ~[na:na]`

`at java.base/java.net.InetAddress.getAllByName(InetAddress.java:1301) ~[na:na]`

`at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:133) ~[mysql-connector-java-8.0.28.jar!/:8.0.28]`

`at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:63) ~[mysql-connector-java-8.0.28.jar!/:8.0.28]`

`... 42 common frames omitted`
#2

Pesquisando aqui, vi isso:

By default Compose sets up a single network for your app. Each container for a service joins the default network and is both reachable by other containers on that network, and discoverable by them at a hostname identical to the container name.

Pelo que entendi, parece que, por padrão, uma única rede é usada por todas as aplicações e os containers podem acessar outros pelo nome. Ou seja, vc pode fazer um teste e tentar executar esse compose sem qualquer configuração de network para ver se funciona.

FONTE: Networking in Compose | Docker Documentation