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Im trying to run a spring boot application with redis locally using docker. The app cannot seems to connect with the redis container.

My Dockerfile

FROM java:8
VOLUME /tmp
ADD target/test-*.jar test.jar
RUN bash -c 'touch /test.jar'
EXPOSE 8080
ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/test.jar"]

docker-compose.yml

version: '2'
services:
  app:
    build: .
    ports:
      - "8080:8080"
    links:
      - "db:redis"
  db:
    image: "redis:alpine"
    hostname: redis
    ports:
      - "6379:6379"

application properties

spring.redis.host=redis

When the application try to connect to the database it throws

Cannot get Jedis connection; nested exception is redis.clients.jedis.exceptions.JedisConnectionException: Could not get a resource from the pool] with root cause
app_1  | 
app_1  | java.net.ConnectException: Connection refused (Connection refused)

Code that i use to connect to db

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

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

any help would be really appreciated. Thanks

Dilantha
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  • Does this answer your question? [When to use --hostname in docker?](https://stackoverflow.com/questions/43031100/when-to-use-hostname-in-docker) – Turing85 Sep 03 '20 at 20:32
  • What you probably want is an [alias](https://docs.docker.com/compose/compose-file/#aliases) for `db` or just call the container by its service name `db`. – Turing85 Sep 03 '20 at 20:35
  • spring.redis.port is set? how do you connect to the redis in your code? – ferdy Sep 03 '20 at 20:38
  • @Turing85 Do you mean using links: - "db" instead of links: - "db:redis" ? – Dilantha Sep 03 '20 at 21:04
  • Yes. [Or forego `links` alltogether since it is deprecated](https://docs.docker.com/compose/compose-file/#links) and use [`depends_on`](https://docs.docker.com/compose/compose-file/#depends_on) or [user-defined networks](https://docs.docker.com/compose/networking/). – Turing85 Sep 03 '20 at 21:06
  • @ferdyi tried adding the port as well.. but didnt work. i modified my question with the code im using – Dilantha Sep 03 '20 at 21:07
  • I tried it with a python client. Your code works for me. Therefore I think it has to do with the java networking actually not being able to resolve "redis" to a real host. I'd have been thinking, the "links" creating hard connections in your containers /etc/hosts file, but actually i am not quite sure about this. – ferdy Sep 03 '20 at 21:13
  • I've tried directly using jredis in groovy and it worked. I also used spring along with java and jredis as you did and it worked. Did you run a clean `docker-compose build` in between? Do you have a VPN connection while you work with containers? Which OS you're working with? How exactly does your code look like? I need to reproduce your error to understand it better. – ferdy Sep 03 '20 at 22:33
  • @ferdy Thanks for the help. after i removed the beans where it creates JedisConnectionFactory and RedisTemplate it worked ! – Dilantha Sep 04 '20 at 13:43

1 Answers1

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Change your docker-compose.yml file link in app service to - links: - "db". When making a link between two services, you dont need to add the hostname. The hostname will be used to refer in your code. Which you have done correctly in your applications.properties file.

Sahil Yadav
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  • Thanks for your reply. I tried that.. but still giving the same exception – Dilantha Sep 03 '20 at 21:23
  • "*The hostname will be used to refer in your code.*" - No. The hostname sets the hostname in the container it is specified on (i.e. pinging the hostname from within the container will result in pinging localhost) – Turing85 Sep 03 '20 at 21:24