Docker Spring Boot Postgres Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections - postgresql

Question

It is my first time trying to put my Springboot application into one docker container and my PostgresDB into another container.
application.properties:
spring.datasource.url=jdbc:postgresql://localhost:5432/esteticcenter
spring.datasource.username=postgres
spring.datasource.password=admin
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.PostgreSQLDialect
spring.jpa.hibernate.ddl-auto = update
dockerfile:
FROM openjdk:8-jdk-alpine
VOLUME /tmp
EXPOSE 8082
RUN mkdir -p /app/
RUN mkdir -p /app/logs/
ADD target/postgres-demo-0.0.1-SNAPSHOT.jar /app/app.jar
ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app/app.jar"]
docker-compose.yml:
version: "3"
services:
postgres:
image: postgres:latest
network_mode: bridge
container_name: postgres
volumes:
- postgres-data:/var/lib/postgresql/data
expose:
- 5432
ports:
- 5432:5432
environment:
- POSTGRES_PASSWORD=admin
- POSTGRES_USER=postgres
- POSTGRES_DB=esteticcenter
restart: unless-stopped
# APP*****************************************
springbootapp:
image: springbootapp:latest
network_mode: bridge
container_name: springbootapp
expose:
- 8080
ports:
- 8080:8080
restart: unless-stopped
depends_on:
- postgres
links:
- postgres
volumes:
postgres-data:
Error: 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 tried to replace the "localhost" with dbpostgresql or db but in spring.datasource.url like many answers I checked but then "mvn clean package" fails and I can not create the jar. What am I missing here?

Answer 1

Docker compose will create a dedicated network with DNS for your services. Each service will get the service name as hostname (as defined in docker-compose.yml).
Other containers can be accessed from inside this network by their service name.
Changing the hostname for the database in your application.properties file should fix the issue:
spring.datasource.url=jdbc:postgresql://postgres:5432/esteticcenter