Spring boot, postgres inside docker compose cannot reach localhost

Question

I have Spring boot web application with a Postgres database. I created docker-compose file

version: '3.1'
services:
  app:
    container_name: springboot-postgresql
    image: springboot-postgresql
    build: ./
    restart: always
    #Environment variables for Spring Boot Application.
    environment:
      - DB_SERVER=postgresqldb
      - POSTGRES_DB=my_database
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=postgres
    ports:
      - "8080:8080"
    depends_on:
      - postgresqldb

  postgresqldb:
    image: postgres
    ports:
      - "5432:5432"
    environment:
      - POSTGRES_PASSWORD=postgres
      - POSTGRES_USER=postgres
      - POSTGRES_DB=my_database

and Dockerfile

FROM adoptopenjdk/openjdk15:alpine-jre
VOLUME /tmp
COPY target/*.jar app.jar
ENTRYPOINT ["java","-jar","/app.jar"]
EXPOSE 8080

and also application.properties file:

spring.datasource.url=jdbc:postgresql://${DB_SERVER}/${POSTGRES_DB}
spring.datasource.username=${POSTGRES_USER}
spring.datasource.password=${POSTGRES_PASSWORD}
spring.jpa.hibernate.ddl-auto=create

spring.freemarker.expose-request-attributes=true
spring.freemarker.suffix= .ftl

address=http://localhost:8080/

server.error.whitelabel.enabled=false

# =========================== MAIL ===========================
spring.jpa.properties.hibernate.jdbc.lob.non_contextual_creation=true

spring.mail.host=***
spring.mail.username=***
spring.mail.password=***
spring.mail.port=465
spring.mail.protocol=smtps
mail.smtp.auth=true
mail.debug=true

# =========================== SESSIONS ===========================
spring.session.jdbc.initialize-schema=always
spring.session.jdbc.table-name=SPRING_SESSION

# =========================== THYMELEAF ===========================
spring.thymeleaf.prefix=classpath:/templates/
spring.thymeleaf.suffix=.html
spring.thymeleaf.mode=HTML5
spring.thymeleaf.encoding=UTF-8
spring.thymeleaf.content-type=text/html # ;charset=<encoding> is added
spring.thymeleaf.cache=true

After I run docker-compose up all the services started and everything is working well:

...
springboot-postgresql | 2021-01-11 13:20:20.703  INFO 1 --- [           main] DeferredRepositoryInitializationListener : Triggering deferred initialization of Spring Data repositories…
springboot-postgresql | 2021-01-11 13:20:21.268  INFO 1 --- [           main] DeferredRepositoryInitializationListener : Spring Data repositories initialized!
springboot-postgresql | 2021-01-11 13:20:21.306  INFO 1 --- [           main] com.example.semestral_work.Application   : Started Application in 15.753 seconds (JVM running for 17.887)

But I can't visit http://localhost:8080/ link because of ERR_CONNECTION_REFUSED . The server looks like it is running, but I can't visit any page of this app. What I'm doing wrong, please?

Answer 1

because your tomcat of spring did not start yet. for that, you need to start docker or the spring application in a different terminal.