I am sure that all containers are in the same network.
I can connect with redis-cli to redisContainer

If i start my spring boot app from ide (not in docker container), all fine

I only receive this error message below, without any particular explanations

I am sure that spring boot app receives correct env variables from compose file

I tried to remove “hosts: ” from redis container, i tried to set REDIS_HOST to localhost in backend container

version: '3.8'
services:

  db:
    image: postgres:latest
    container_name: postgresql_container
    environment:
      POSTGRES_DB: insight
      POSTGRES_USER: admin
      POSTGRES_PASSWORD: admin
    ports:
      - "15432:5432"
    volumes:
      - postgres_data:/var/lib/postgresql/data
    restart: always

  redis:
    image: redis:latest
    container_name: redisContainer
    ports:
      - "6379:6379"

  backend:
    build: .
    container_name: backendContainer
    ports:
      - "8081:8082"
    environment:
      REDIS_PORT: 6379
      REDIS_HOST: redis

      SPRING_DATASOURCE_URL: jdbc:postgresql://db:5432/insight
      SPRING_DATASOURCE_USERNAME: admin
      SPRING_DATASOURCE_PASSWORD: admin

    depends_on:
      - db
    restart: always

volumes:
  postgres_data:

application.yaml

spring:
  datasource:
    driver-class-name: org.postgresql.Driver
    url: ${SPRING_DATASOURCE_URL}
    username: ${SPRING_DATASOURCE_USERNAME}
    password: ${SPRING_DATASOURCE_PASSWORD}
  jpa:
    show-sql: true
    hibernate:
      ddl-auto: update
    database-platform: org.hibernate.dialect.PostgreSQLDialect
  redis:
    host: ${REDIS_HOST}
    port: ${REDIS_PORT}
server:
  port: 8082


logging:
  level:
    org.springframework.data.redis: DEBUG

The error message:

2024-12-23 18:36:48 2024-12-23T15:36:48.226Z ERROR 1 --- [nio-8082-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet 
[dispatcherServlet] in context with path [] threw exception [Request processing failed: org.springframework.data.redis.RedisConnectionFailureException: 
Unable to connect to Redis] with root cause
2024-12-23 18:36:48 
2024-12-23 18:36:48 java.net.ConnectException: Connection refused
2024-12-23 18:36:48     at java.base/sun.nio.ch.Net.pollConnect(Native Method) ~[na:na]
2024-12-23 18:36:48     at java.base/sun.nio.ch.Net.pollConnectNow(Net.java:672) ~[na:na]
2024-12-23 18:36:48     at java.base/sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:946) ~[na:na]
2024-12-23 18:36:48     at io.netty.channel.socket.nio.NioSocketChannel.doFinishConnect(NioSocketChannel.java:336) ~[netty-transport-4.1.114.Final.jar!/:4.1.114.Final]
2024-12-23 18:36:48     at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.finishConnect(AbstractNioChannel.java:339) ~[netty-transport-4.1.114.Final.jar!/:4.1.114.Final]
2024-12-23 18:36:48     at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:776) ~[netty-transport-4.1.114.Final.jar!/:4.1.114.Final]
2024-12-23 18:36:48     at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:724) ~[netty-transport-4.1.114.Final.jar!/:4.1.114.Final]
2024-12-23 18:36:48     at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:650) ~[netty-transport-4.1.114.Final.jar!/:4.1.114.Final]
2024-12-23 18:36:48     at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562) ~[netty-transport-4.1.114.Final.jar!/:4.1.114.Final]
2024-12-23 18:36:48     at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997) ~[netty-common-4.1.114.Final.jar!/:4.1.114.Final]
2024-12-23 18:36:48     at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.114.Final.jar!/:4.1.114.Final]
2024-12-23 18:36:48     at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.114.Final.jar!/:4.1.114.Final]
2024-12-23 18:36:48     at java.base/java.lang.Thread.run(Thread.java:833) ~[na:na]
2024-12-23 18:36:48

I have these two dependencies about redis

    <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-cache</artifactId>
        </dependency>

i have no redis configs, the app works fine with redis if it is started not from container