Spring Boot, PostgreSQL, and Docker - Connection Refused whil Running in Container

Question

I am attempting to build a "service" consisting of a Spring Boot application and PostgreSQL database. I have been able to access the database (running in a container) from the Spring Boot app while the Spring Boot application was running on my local machine. Now, when I attempt to move the Spring Boot application to a container, I am received the following error:

inventory_1  | 2018-01-20 18:43:06.108 ERROR 1 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.transaction.CannotCreateTransactionException: Could not open JPA EntityManager for transaction; nested exception is org.hibernate.exception.JDBCConnectionException: Unable to acquire JDBC Connection] with root cause
inventory_1  |
inventory_1  | java.net.ConnectException: Connection refused (Connection refused)

However, I am able to connect to DB from my local machine: psql -h localhost -p 5000 -U kelly_psql -d leisurely_diversion

My application.properties file:

spring.jpa.hibernate.ddl-auto=none
spring.jpa.show-sql=false
spring.jpa.database-platform=org.hibernate.dialect.PostgreSQLDialect
spring.datasource.url=jdbc:postgresql://localhost:5432/leisurely_diversion
spring.datasource.username=kelly_psql
spring.datasource.password=pass
spring.datasource.driver-class-name=org.postgresql.Driver

My docker-compose file:

    # Use postgres/example user/password credentials
version: '3.2'

services:
  db:
    image: postgres
    ports:
      - 5000:5432
    environment:
      POSTGRES_PASSWORD: example
    volumes:
      - type: volume
        source: psql_data
        target: /var/lib/postgresql/data
    networks: 
      - app
    restart: always
  inventory:
    image: kellymarchewa/inventory_api
    depends_on:
        - db
    ports:
      - 8080:8080
    networks:
      - app
    restart: always
volumes:
  psql_data:
networks: 
  app:

My Dockerfile (from the Spring website)

FROM openjdk:8-jdk-alpine
VOLUME /tmp
ARG JAR_FILE
ADD ${JAR_FILE} app.jar
ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app.jar"]

I suspect the issue lies in a misunderstanding (on my part) of Docker or containers, but I am not sure. Any advice would be appreciated.

Answer 1

You are pointing your application towards localhost, but this is not shared between containers.

To access another container you have to refer to its hostname.

In your case, I understand that you want the inventory service to access the db service. So you should use the following datasource url:

spring.datasource.url=jdbc:postgresql://db:5432/leisurely_diversion

See this simple tutorial about connecting to a container from another container with docker compose: https://docs.docker.com/compose/gettingstarted/

Answer 2

Like in my case if you are using Docker Toolbox for windows 8.1 then you cannot use "localhost",

Instead you have to use docker machine ip;

 host> docker-machine ip default

 192.168.99.100

After that your url will look like;

 spring.datasource.url=jdbc:postgresql://192.168.99.100:5432/bankdb

This will successfully connect to docker Postgres DB.

Cheers!!