Docker: Springboot container can not connect to PostgreSql Container Connection error

Question

I am building my first Springboot 2.0 application. I am trying to put my Springboot application into one docker container and my PostgresDB into another container.

Answer 1

You're missing networking configuration in your docker-compose.yml specification. By using "networks" you can effectively communicate between containers by their service name (using dns, the service name as the hostname).

Here is an updated docker-compose.yml:

version: "2.1"

services:
  springboot-api-demo:
    image: "fw/springboot-api-demo"
    mem_limit: 1024m
    ports:
      - "8080:8080"
    environment:
      - SPRING_PROFILES_ACTIVE=local
      - AWS_REGION=local
      - ENVIRONMENT=local
      - AUTH_ENABLED=false
    networks:
      - mynet

  postgres:
    container_name: pgdb
    image: postgres:9.6-alpine
    environment:
    - 'POSTGRES_ROOT_PASSWORD=postgres'
    - 'POSTGRES_USER=postgres'
    - 'POSTGRES_PASSWORD=postgres'
    ports:
    - "54321:5432"
    networks:
    - mynet

networks:
  mynet:
    driver: bridge

Your database url should look like spring.datasource.url=jdbc:postgresql://postgres:5432/java_learning (notice the hostname, postgres, is equal to that of the service name.

Answer 2

Try with :

spring.datasource.url= jdbc:postgresql://pgdb:5432/java_learning

The postgres database is not running on localhost, it's running in the other container which has an other IP (yet unknown).

Thanksfully, docker-compose automatically create a network shared among all the containers in the docker-compose.yml (unless explicitly said to do not), as a result you can magically use the service name as an hostname.

Also, you have a typo in the port, Postgres use 5432 by default, not 54321

Answer 3

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.

you should use the following datasource url:

spring.datasource.url=jdbc:postgresql://pgdb:5432/java_learning

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