Docker Compose + Spring Boot + Postgres connection

Question

I have a Java Spring Boot app which works with a Postgres database. I want to use Docker for both of them. I initially put just the Postgres in Docker, and I had a docker-compose.yml file defined like this:

version: '2'
services:
    db:
        container_name: sample_db
        image: postgres:9.5
        volumes:
            - sample_db:/var/lib/postgresql/data
        environment:
            - POSTGRES_PASSWORD=sample
            - POSTGRES_USER=sample
            - POSTGRES_DB=sample
            - PGDATA=/var/lib/postgresql/data/pgdata
        ports:
            - 5432:5432

volumes:
    sample_db: {}

Then, when I issued the commands sudo dockerd and sudo docker-compose -f docker-compose.yml up , it was starting the database. I could connect using pgAdmin for example, by using localhost as server and port 5432 . Then, in my Spring Boot app, inside the application.properties file I defined the following properties.

spring.datasource.url=jdbc:postgresql://localhost:5432/sample
spring.datasource.username=sample
spring.datasource.password=sample
spring.jpa.generate-ddl=true

At this point I could run my Spring Boot app locally through Spring Suite, and it all was working fine. Then, I wanted to also add my Spring Boot app as Docker image. I first of all created a Dockerfile in my project directory, which looks like this:

FROM java:8
EXPOSE 8080
ADD /target/manager.jar manager.jar
ENTRYPOINT ["java","-jar","manager.jar"]

Then, I entered to the directory of the project issued mvn clean followed by mvn install . Next, issued docker build -f Dockerfile -t manager. followed by docker tag 9c6b1e3f1d5e myuser/manager:latest (the id is correct). Finally, I edited my existing docker-compose.yml file to look like this:

version: '2'
services:
    web:
      image: myuser/manager:latest
      ports: 
          - 8080:8080
      depends_on:
          - db
    db:
        container_name: sample_db
        image: postgres:9.5
        volumes:
            - sample_db:/var/lib/postgresql/data
        environment:
            - POSTGRES_PASSWORD=sample
            - POSTGRES_USER=sample
            - POSTGRES_DB=sample
            - PGDATA=/var/lib/postgresql/data/pgdata
        ports:
            - 5432:5432

volumes:
    sample_db: {}

But, now if I issue sudo docker-compose -f docker-compose.yml up command, the database again starts correctly, but I get errors and exit code 1 for the web app part. The problem is the connection string. I believe I have to change it to something else, but I don't know what it should be. I get the following error messages:

web_1  | 2017-06-27 22:11:54.418 ERROR 1 --- [           main] o.a.tomcat.jdbc.pool.ConnectionPool      : Unable to create initial connections of pool.
web_1  | 
web_1  | org.postgresql.util.PSQLException: Connection to localhost:5432 refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections

Any ideas?

Answer 1

Each container has its own network interface with its own localhost. So change how Java points to Postgres:

spring.datasource.url=jdbc:postgresql://localhost:5432/sample

Answer 2

I had the same problem and I lost some time to understand and solve this problem:

org.postgresql.util.PSQLException: Connection to localhost:5432 refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.

I show all the properties so that everyone understands.
application.properties:

spring.datasource.url=jdbc:postgresql://localhost:5432/testdb
spring.datasource.driver-class-name=org.postgresql.Driver
spring.datasource.username=postgres
spring.datasource.password=postgres
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.PostgreSQL82Dialect
spring.jpa.hibernate.ddl-auto=update

docker-compose.yml:

  version: "3"
  services:
    springapp:
      build: .
      container_name: springapp
      environment:
        SPRING_DATASOURCE_URL: jdbc:postgresql://db:5432/testdb
      ports:
        - 8000:8080
      restart: always
      depends_on:
        - db
    db:
      image: postgres
      container_name: db
      environment:
        - POSTGRES_USER=postgres
        - POSTGRES_PASSWORD=postgres
        - POSTGRES_DB=testdb
        - PGDATA=/var/lib/postgresql/data/pgdata
      ports:
        - 5000:5432
      volumes:
        - pgdata:/var/lib/postgresql/data
      restart: always
  volumes:
    pgdata:

For start spring application with local database we use url localhost.
For connect to container with database we need change 'localhost' on your database service, in my case ' localhost ' to ' db '.

Solution : add SPRING_DATASOURCE_URL environment in docker-compose.yml wich rewrite spring.datasource.url value for connect:

  environment:
    SPRING_DATASOURCE_URL: jdbc:postgresql://db:5432/testdb

I hope this helps someone save his time.

Answer 3

You can use this.

version: "2"
services:
    sample_db-postgresql:
        image: postgres:9.5
        ports:
            - 5432:5432
        environment:
            - POSTGRES_PASSWORD=sample
            - POSTGRES_USER=sample
            - POSTGRES_DB=sample
         volumes:
            - sample_db:/var/lib/postgresql/data

volumes:
    sample_db:

Answer 4

You can use ENV variable to change the db address in your docker-compose. Dockerfile:

FROM java:8
EXPOSE 8080
ENV POSTGRES localhost
ADD /target/manager.jar manager.jar
ENTRYPOINT exec java $JAVA_OPTS -jar manager.jar --spring.datasource.url=jdbc:postgresql://$POSTGRES:5432/sample

docker-compose: `

  container_name: springapp
  environment:
   - POSTGRES=db`