com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure when trying to build spring boot docker image

Question

I am trying to build my docker image for my spring boot application but keep encountering this error:

 :: Spring Boot ::        (v2.2.5.RELEASE)

2020-05-31 02:18:39.820  INFO 63 --- [           main] c.g.Apollo.ApolloApplicationTests        : Starting ApolloApplicationTests on 4b284b60945e with PID 63 (started by root in /build)
2020-05-31 02:18:39.838  INFO 63 --- [           main] c.g.Apollo.ApolloApplicationTests        : No active profile set, falling back to default profiles: default
2020-05-31 02:18:42.208  INFO 63 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data JPA repositories in DEFAULT mode.
2020-05-31 02:18:42.467  INFO 63 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 216ms. Found 3 JPA repository interfaces.
2020-05-31 02:18:44.902  INFO 63 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
2020-05-31 02:18:46.575 ERROR 63 --- [           main] com.zaxxer.hikari.pool.HikariPool        : HikariPool-1 - Exception during pool initialization.

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-8.0.20.jar:8.0.20]
        at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-java-8.0.20.jar:8.0.20]
        at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836) ~[mysql-connector-java-8.0.20.jar:8.0.20]
        at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456) ~[mysql-connector-java-8.0.20.jar:8.0.20]
        at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246) ~[mysql-connector-java-8.0.20.jar:8.0.20]
        at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:197) ~[mysql-connector-java-8.0.20.jar:8.0.20]
        at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:138) ~[HikariCP-3.4.2.jar:na]
        at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:354) ~[HikariCP-3.4.2.jar:na]
        at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:202) ~[HikariCP-3.4.2.jar:na]
        at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:473) ~[HikariCP-3.4.2.jar:na]
        at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:554) ~[HikariCP-3.4.2.jar:na]
        at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115) ~[HikariCP-3.4.2.jar:na]
        at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112) ~[HikariCP-3.4.2.jar:na]

Terminal when successfully running in intellij:

 :: Spring Boot ::        (v2.2.5.RELEASE)

2020-05-31 01:04:39.322  INFO 19524 --- [  restartedMain] c.g.Apollo.ApolloApplication             : Starting ApolloApplication on asd-PC with PID 19524 (C:\Projects\Apollo\target\classes started by asd in C:\Projects\Apollo)
2020-05-31 01:04:39.324  INFO 19524 --- [  restartedMain] c.g.Apollo.ApolloApplication             : No active profile set, falling back to default profiles: default
2020-05-31 01:04:39.354  INFO 19524 --- [  restartedMain] o.s.b.devtools.restart.ChangeableUrls    : The Class-Path manifest attribute in C:\Users\asd\.m2\repository\org\glassfish\jaxb\jaxb-runtime\2.3.2\jaxb-runtime-2.3.2.jar referenced one or more files that do not exist: file:/C:/Users/asd/.m2/repository/org/glassfish/jaxb/jaxb-runtime/2.3.2/jakarta.xml.bind-api-2.3.2.jar,file:/C:/Users/asd/.m2/repository/org/glassfish/jaxb/jaxb-runtime/2.3.2/txw2-2.3.2.jar,file:/C:/Users/asd/.m2/repository/org/glassfish/jaxb/jaxb-runtime/2.3.2/istack-commons-runtime-3.0.8.jar,file:/C:/Users/asd/.m2/repository/org/glassfish/jaxb/jaxb-runtime/2.3.2/stax-ex-1.8.1.jar,file:/C:/Users/asd/.m2/repository/org/glassfish/jaxb/jaxb-runtime/2.3.2/FastInfoset-1.2.16.jar,file:/C:/Users/asd/.m2/repository/org/glassfish/jaxb/jaxb-runtime/2.3.2/jakarta.activation-api-1.2.1.jar
2020-05-31 01:04:39.354  INFO 19524 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
2020-05-31 01:04:39.354  INFO 19524 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
2020-05-31 01:04:39.785  INFO 19524 --- [  restartedMain] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data JPA repositories in DEFAULT mode.
2020-05-31 01:04:39.846  INFO 19524 --- [  restartedMain] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 54ms. Found 3 JPA repository interfaces.
2020-05-31 01:04:40.214  INFO 19524 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2020-05-31 01:04:40.220  INFO 19524 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2020-05-31 01:04:40.221  INFO 19524 --- [  restartedMain] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.31]
2020-05-31 01:04:40.293  INFO 19524 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2020-05-31 01:04:40.293  INFO 19524 --- [  restartedMain] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 939 ms
2020-05-31 01:04:40.365  INFO 19524 --- [  restartedMain] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
2020-05-31 01:04:40.702  INFO 19524 --- [  restartedMain] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Start completed.
2020-05-31 01:04:40.731  INFO 19524 --- [  restartedMain] o.hibernate.jpa.internal.util.LogHelper  : HHH000204: Processing PersistenceUnitInfo [name: default]
2020-05-31 01:04:40.800  INFO 19524 --- [  restartedMain] org.hibernate.Version                    : HHH000412: Hibernate ORM core version 5.4.12.Final
2020-05-31 01:04:40.919  INFO 19524 --- [  restartedMain] o.hibernate.annotations.common.Version   : HCANN000001: Hibernate Commons Annotations {5.1.0.Final}
2020-05-31 01:04:41.006  INFO 19524 --- [  restartedMain] org.hibernate.dialect.Dialect            : HHH000400: Using dialect: org.hibernate.dialect.MySQL8Dialect
2020-05-31 01:04:41.407  INFO 19524 --- [  restartedMain] o.h.e.t.j.p.i.JtaPlatformInitiator       : HHH000490: Using JtaPlatform implementation: [org.hibernate.engine.transaction.jta.platform.internal.NoJtaPlatform]
2020-05-31 01:04:41.413  INFO 19524 --- [  restartedMain] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'default'
2020-05-31 01:04:41.650  WARN 19524 --- [  restartedMain] JpaBaseConfiguration$JpaWebConfiguration : spring.jpa.open-in-view is enabled by default. Therefore, database queries may be performed during view rendering. Explicitly configure spring.jpa.open-in-view to disable this warning
2020-05-31 01:04:41.717  INFO 19524 --- [  restartedMain] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2020-05-31 01:04:41.967  INFO 19524 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
2020-05-31 01:04:41.995  INFO 19524 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2020-05-31 01:04:41.997  INFO 19524 --- [  restartedMain] c.g.Apollo.ApolloApplication             : Started ApolloApplication in 2.911 seconds (JVM running for 3.899)

My Dockerfile:

FROM maven:3.6.3-jdk-11-slim AS MAVEN_BUILD

COPY pom.xml /build/
COPY src /build/src/
WORKDIR /build/
RUN mvn package

FROM openjdk:11-jre-alpine

WORKDIR /app
COPY --from=MAVEN_BUILD /build/target/*.war /app/app.war
ENTRYPOINT ["java", "-jar", "app.war"]

My application.properties:

## GraphQL SPQR ##
server.port=8080
graphql.spqr.gui.enabled=true
graphql.spqr.http.endpoint=/graphql
graphql.spqr.ws.endpoint=/graphql

## Database Properties ##
spring.datasource.url=jdbc:mysql://localhost:3306/innodb
spring.datasource.username=root
spring.datasource.password=1234

My application works when I build and run the project in Intellij but not when I try and build my docker image. I am using MySQL and have just been connecting on localhost on port 3306.

Answer 1

The error message seems to indicate the issue is failing to connect to the database. From your settings, it appears that you are trying to connect to the DB using localhost:3306. That will not work when you are running the application in a container because docker creates its own network which is separate from you machine’s network. So, localhost in the container does not refer to your machine. You need to instead setup a docker network that will allow your container to access the database in a specific IP address. Here is an article with the specifics: https://nickjanetakis.com/blog/docker-tip-35-connect-to-a-database-running-on-your-docker-host Note that I have assumed from your post, that the DB is installed in your host machine. If it is not and the DB is running in its own container, the you need to create a docker network and attach both containers to that network.