Docker Redis Connection refused

Question

I'm trying to access Redis server through the code and it's not connecting. But if i bash to the redis container i can access the redis-cli.

docker-compose.yml looks like this

version: '2'
services:
  web:
   build:
    context: .
    dockerfile: Dockerfile_nginx
   ports:
    - "9000:80"
   environment:
    - NGINX_SERVERNAME=xxx.dev *.xxx.dev
   command: /bin/bash -c "envsubst '$$NGINX_SERVERNAME' < /var/www/site.template > /etc/nginx/conf.d/default.conf
                          && dos2unix /var/www/provision/init_storage.sh && sh /var/www/provision/init_storage.sh
                          && nginx -g 'daemon off;'"
   volumes:
     - .:/var/www
   links:
     - php
   networks:
     frontend

  php:
    build:
      context: .
      dockerfile: Dockerfile_php-fpm
    command: /bin/bash -c "composer install
              && php-fpm"
    volumes:
          - .:/var/www
    environment:
          - APP_ENV=local
          - APP_DEBUG=true
    networks:
      - frontend
      - backend
    links:
         - redis
  db:
    build:
      context: .
      dockerfile: Dockerfile_mariadb
    volumes:
      - ./initdb:/docker-entrypoint-initdb.d
    ports:
      - "3309:3306"
    environment:
      MYSQL_ROOT_PASSWORD: xxxx
      MYSQL_DATABASE: xxxx
    networks:
      - backend
  redis:
    build:
      context: .
      dockerfile: Dockerfile_redis
    ports:
      - "6379:6379"

networks:
  frontend:
    driver: bridge
  backend:
    driver: bridge

Dockerfile_redis

FROM redis:latest

When i try to connect to the redis server using this code

$redis = new \Redis();
    try {
        $redis->connect('127.0.0.1', 6379);
    } catch (\Exception $e) {
        var_dump($e->getMessage())  ;
        die;
    }

It gives this warning

Warning: Redis::connect(): connect() failed: Connection refused

Does anyone know how to connect Redis container to PHP container ?

Solution 1

Your Problem

Docker Compose creates separated docker container for different services. Each container are, logically speaking, like different separated computer servers that only connected with each other through docker network.

Consider each boxes in this diagram as an individual computer, then this is practically what you have:

+----------------------------------------------------------+
|                       your machine                       |
+----------------------------------------------------------+
                               |                    
        +------ (virtual network by docker) -------+
        |                      |                   |
+-----------------+ +-------------------+ +----------------+
| "php" container | | "redis" container | | "db" container |
+-----------------+ +-------------------+ +----------------+

Your PHP container doesn't see any redis in "localhost" because there is no redis in it. Just like it would't see any MySQL in "localhost". Your redis is running in the "redis" container. Your MySQL is running in your "db" container.

The things that confuses you is the port binding directives (i.e. ports in this definition):

redis:
  build:
    context: .
    dockerfile: Dockerfile_redis
  ports:
    - "6379:6379"

The port 6379 of the "redis" container is binded to your computer, but to your computer ONLY. Other container doesn't have the same access to the port bindings. So even your computer can connect it with '127.0.0.1:6379', the php container cannot do the same.

Solution

As described in Networking in Docker Compose, each docker compose container can access other container by using the service name as hostname. For example, your programming running by service php can access your MySQL service with the hostname db.

So you should connect redis with its hostname redis

$redis = new \Redis();
try {
    $redis->connect('redis', 6379);
} catch (\Exception $e) {
    var_dump($e->getMessage())  ;
    die;
}

Solution 2

just remove the redis port and change the redis hostname to redis in your Laravel project .env file.

REDIS_HOST=redis
#REDIS_PORT=6379

Solution 3

If using a static-ip for your network use below instead of localhost

$redis->connect('<static-ip>', 6379);

Comments

[Isuru Buddhika]

Forgot to mention that I've added networks. redis: build: context: . dockerfile: Dockerfile_redis networks: - frontend - backend

[TimCO]

great ascii diagram and explanation!

[Prasan Dutt]

Good explanation, I had similar problem for python program. I started the docker image with outbound port and network as host to make it accessible from python client program.