How can i connect to the oracle database between docker containers?

I have two containers that is created from docker-compose, one has api with springboot and the other oracle database, however it does’n connect the api to the database and I already ran out options, I tried configure the connection in the aplication.properties and also docker-compose.yml

This is docker-compose.yml

version: "3.7"
services:
  app:
    image: "bm_spring_boot:latest"
    build:
      context: ./BmApiRestV2/
      dockerfile: Dockerfile
    container_name: api_spring
    depends_on:
      - db
    ports:
      - 8888:8080
    environment:
      - SPRING_DATASOURCE_URL=jdbc:oracle:thin:@//db:49161/xe
      - SPRING_DATASOURCE_USERNAME=system
      - SPRING_DATASOURCE_PASSWORD=oracle
    networks:
      spring-net:
        aliases:
          - spring-host

  db:
    image: oracleinanutshell/oracle-xe-11g:latest
    container_name: oracle_db
    ports:
      - 49161:1521
      - 5500:5500
    environment:
      - ORACLE_ALLOW_REMOTE=true
    networks:
      spring-net:
        aliases:
          - db-host
networks:
  spring-net:
    driver: bridge
    ipam:
      driver: default

Dockerfile

ARG VERSION=8-jdk-slim
FROM openjdk:${VERSION}
ARG JAR_FILE=BmApiRestV2
COPY "./target/${JAR_FILE}.jar" "app.jar"
EXPOSE 8080
ENTRYPOINT [ "java","-jar","app.jar"]

aplication.properties

#spring.datasource.username=system
#spring.datasource.password=oracle
spring.datasource.driver-class-name=oracle.jdbc.driver.OracleDriver
#DOCKER
#spring.datasource.url=jdbc:oracle:thin:@ (DESCRIPTION =    (ADDRESS_LIST =      (ADDRESS = (PROTOCOL = TCP)(HOST = db)(PORT = 49161))    )    (CONNECT_DATA =      (SID = xe)    )  )

(The connection was commented because in the docker-compose it’s configured)

I appreciate the help (My apologies for my english)

————– UPDATE ————–

Connection test

 ping db
PING db (172.20.0.2) 56(84) bytes of data.
64 bytes from oracle_db.imagenspring_spring-net (172.20.0.2): icmp_seq=1 ttl=64 time=0.221 ms
64 bytes from oracle_db.imagenspring_spring-net (172.20.0.2): icmp_seq=2 ttl=64 time=0.072 ms
64 bytes from oracle_db.imagenspring_spring-net (172.20.0.2): icmp_seq=3 ttl=64 time=0.072 ms
64 bytes from oracle_db.imagenspring_spring-net (172.20.0.2): icmp_seq=4 ttl=64 time=0.072 ms
64 bytes from oracle_db.imagenspring_spring-net (172.20.0.2): icmp_seq=5 ttl=64 time=0.144 ms
64 bytes from oracle_db.imagenspring_spring-net (172.20.0.2): icmp_seq=6 ttl=64 time=0.071 ms
64 bytes from oracle_db.imagenspring_spring-net (172.20.0.2): icmp_seq=7 ttl=64 time=0.161 ms
64 bytes from oracle_db.imagenspring_spring-net (172.20.0.2): icmp_seq=8 ttl=64 time=0.063 ms
^C
--- db ping statistics ---
8 packets transmitted, 8 received, 0% packet loss, time 7090ms
rtt min/avg/max/mdev = 0.063/0.109/0.221/0.054 ms
root@2254b03a8ef4:/#

Answer

TLDR

Change the port to 1521 in your connection string.

Extended version

Your services and networking are configure properly. Both containers are in the same docker network, which allows them to communicate with each other.

Also, contrary to some of the comments, all 3 ways of calling the containers are correct:

• db
• db-host
• oracle_db.

This can be easily verified using a simplified docker-compose.yml, just to test the connectivity:

version: "3.7"
services:
  app:
    image: busybox
    command: "sh -c 'sleep 3600;'"
    networks:
      spring-net:
        aliases:
          - app-host
  db:
    image: busybox
    command: "sh -c 'sleep 3600;'"
    container_name: oracle_db
    networks:
      spring-net:
        aliases:
          - db-host
networks:
  spring-net:
    driver: bridge
    ipam:
      driver: default

If you try to resolve the names – they all point to the same container:

/ # ping db
PING db (172.21.0.2): 56 data bytes
64 bytes from 172.21.0.2: seq=0 ttl=64 time=0.593 ms
^C
--- db ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss
round-trip min/avg/max = 0.593/0.593/0.593 ms
/ # ping oracle_db
PING oracle_db (172.21.0.2): 56 data bytes
64 bytes from 172.21.0.2: seq=0 ttl=64 time=0.213 ms
^C
--- oracle_db ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss
round-trip min/avg/max = 0.213/0.213/0.213 ms
/ # ping db-host
PING db-host (172.21.0.2): 56 data bytes
64 bytes from 172.21.0.2: seq=0 ttl=64 time=0.334 ms
^C
--- db-host ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss
round-trip min/avg/max = 0.334/0.334/0.334 ms

In fact, the problem seems to be with your connection string:

- SPRING_DATASOURCE_URL=jdbc:oracle:thin:@//db:49161/xe

port 49161 is the host port, while your connecting to the container (db). In this case you should be using the 1521 port, which the server inside the container is bound to.