Combining Spring boot and redis with docker-compose: Connection refused

I am trying to do a basic docker container(s) with spring boot and MongoDB and redis. Mongo is just fine but connection can’t be established between redis and spring boot although the configuration looks ok to me.

docker-compose.yml

version: "3.9"
services:
  web:
    build: .
    ports:
      - "1234:1234"
    depends_on:
      - redis
      - db
  db:
    image: mongo
    hostname: mongodb
    ports:
      - "27017:27017"
  redis:
    hostname: redis
    image: redis
    restart: always
    ports:
      - "6379:6379"

Dockerfile:

FROM adoptopenjdk:11
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} app.jar
ENTRYPOINT ["java","-jar","/app.jar"]

Config.java:

@Configuration
@EnableRedisRepositories
public class Config
{

    RedisStandaloneConfiguration standaloneConfiguration() {
        return new RedisStandaloneConfiguration("redis", 6379);
    }

    @Bean
    JedisConnectionFactory jedisConnectionFactory() {
        return new JedisConnectionFactory(standaloneConfiguration());
    }

    @Bean
    public RedisTemplate<String, Object> redisTemplate() {
        RedisTemplate<String, Object> template = new RedisTemplate<>();
        template.setConnectionFactory(jedisConnectionFactory());
        return template;
    }
}

Problem: All the containers are running after docker compose up. but the connection between spring and redis can’t be established.

java.net.ConnectException: Connection refused (Connection refused)
slot-web-1    |     at java.base/java.net.PlainSocketImpl.socketConnect(Native Method) ~[na:na]
slot-web-1    |     at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:399) ~[na:na]
slot-web-1    |     at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:242) ~[na:na]
slot-web-1    |     at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:224) ~[na:na]
slot-web-1    |     at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) ~[na:na]