Docker container crashes at startup on a remote server, how to run correctly?

Question

I have the Spring Boot app and the following Dockerfile:

FROM openjdk:16

COPY build/libs/*.jar tg-bot.jar

ENTRYPOINT java -Dfile.encoding=UTF-8 -jar tg-bot.jar
EXPOSE 8080

The application runs correctly in Docker on my PC:

docker run -p 8080:8080 tg-bot

Then I pushed image to my Dockerhub repository, pull it in Docker on my VPS and tried to run it with the same command:

docker run -p 8080:8080 tg-bot

When the Spring Boot app starts, an error occurs connecting to the PostgreSQL database:

Caused by: org.postgresql.util.PSQLException: The connection attempt failed.
  at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:315) ~[postgresql-42.2.23.jar!/:42.2.23]
  at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:51) ~[postgresql-42.2.23.jar!/:42.2.23]
  at org.postgresql.jdbc.PgConnection.<init>(PgConnection.java:223) ~[postgresql-42.2.23.jar!/:42.2.23]
  at org.postgresql.Driver.makeConnection(Driver.java:465) ~[postgresql-42.2.23.jar!/:42.2.23]
  at org.postgresql.Driver.connect(Driver.java:264) ~[postgresql-42.2.23.jar!/:42.2.23]
  at org.springframework.jdbc.datasource.SimpleDriverDataSource.getConnectionFromDriver(SimpleDriverDataSource.java:144) ~[spring-jdbc-5.3.9.jar!/:5.3.9]
  at org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnectionFromDriver(AbstractDriverBasedDataSource.java:205) ~[spring-jdbc-5.3.9.jar!/:5.3.9]
  at org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnection(AbstractDriverBasedDataSource.java:169) ~[spring-jdbc-5.3.9.jar!/:5.3.9]
  at liquibase.integration.spring.SpringLiquibase.afterPropertiesSet(SpringLiquibase.java:272) ~[liquibase-core-4.3.5.jar!/:na]
  ... 26 common frames omitted
Caused by: java.net.NoRouteToHostException: No route to host
  at java.base/sun.nio.ch.Net.pollConnect(Native Method) ~[na:na]
  at java.base/sun.nio.ch.Net.pollConnectNow(Net.java:669) ~[na:na]
  at java.base/sun.nio.ch.NioSocketImpl.timedFinishConnect(NioSocketImpl.java:549) ~[na:na]
  at java.base/sun.nio.ch.NioSocketImpl.connect(NioSocketImpl.java:597) ~[na:na]
  at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:333) ~[na:na]
  at java.base/java.net.Socket.connect(Socket.java:645) ~[na:na]
  at org.postgresql.core.PGStream.createSocket(PGStream.java:231) ~[postgresql-42.2.23.jar!/:42.2.23]
  at org.postgresql.core.PGStream.<init>(PGStream.java:95) ~[postgresql-42.2.23.jar!/:42.2.23]
  at org.postgresql.core.v3.ConnectionFactoryImpl.tryConnect(ConnectionFactoryImpl.java:98) ~[postgresql-42.2.23.jar!/:42.2.23]
  at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:213) ~[postgresql-42.2.23.jar!/:42.2.23]
  ... 34 common frames omitted

This is my application.yml with db settings:

spring:
  application:
    name: tg-bot
  r2dbc:
    url: r2dbc:postgresql://postgresql.j5321585.myjino.ru:5432/j5321585_tg_db
    username: ********
    password: ********
  liquibase:
    enabled: true
    change-log: classpath:db/scripts/changelog-master.xml
    url: jdbc:postgresql://postgresql.j5321585.myjino.ru:5432/j5321585_tg_db
    user: ********
    password: ********

There are no errors when starting the container locally with the same application.yaml. What could be the problem?

Answer 1

This depends on how you are running your Postgres Application.

If Postgres is running on a separate server make sure that server is accessible from within your Application Docker container.

If Postgres is running as a Docker container on same server, you can start both your application and Postgres Docker container as a docker-compose file. In that you can specify the host or ip-address for the Postgres docker container and use the same in your application code.

Hope this is helpful.