I have a little web servlet application and I would like to initialize and reach my h2 database with tcp and docker-compose but somehow it doesn’t work.

I have this Dockerfile:

FROM maven:3.9.7-eclipse-temurin-11 AS builder

WORKDIR /app

COPY . /app

RUN mvn clean package

FROM tomcat:9.0.89-jre11-temurin-jammy

COPY --from=builder /app/target/*.war $CATALINA_HOME/webapps/ROOT.war

COPY --from=builder /app/target/classes/h2init_ddl_dml.sql $CATALINA_HOME

EXPOSE 8080

CMD ["catalina.sh", "run"]

And this is docker-compose.yml:

services:
  db:
    image: oscarfonts/h2:2.2.224
    container_name: data-database
    hostname: data-database
    restart: no
    environment:
      H2_OPTIONS: '-tcp'
    ports:
      - 1521:1521
    volumes:
      - ./h2init_ddl_dml.sql:/docker-entrypoint-initdb.d/h2init_ddl_dml.sql
  app:
    build: .
    ports:
      - 8080:8080
    container_name: data-application
    depends_on:
      - db

In my maven java web application I would try to use this connection url in my application:

jdbc:h2:tcp://data-database:1521/servlets;DATABASE_TO_UPPER=false;DB_CLOSE_DELAY=-1;

If I use only Dockerfile with in-memory database, with this url, then it works:

jdbc:h2:mem:18_servlets;DATABASE_TO_UPPER=FALSE;INIT=RUNSCRIPT FROM './h2init_ddl_dml.sql';

I tried to check related questions here but I wasn’t able to find the solution in them.

I don’t know whether it is enough information, please let me know if something else could be useful for finding what causes the problem.

Thank you very much for your help in advance.