title: Couldn't establish postgres connection with Wordpress using Docker Compose
body: <p>There is not this kind of question including docker-compose.</p>
  
  <p>I couldn't find what is the problem with my docker-compose.yml file.
  By the way, I don't want to use ready "wp-postgres" image on the docker hub.</p>
  
  <pre><code>version: '3.1'
  
  services:
  
    wordpress:
      image: wordpress
      restart: always
      ports:
        - 8080:80
      environment:
        WORDPRESS_DB_HOST: db
        WORDPRESS_DB_USER: exampleuser
        WORDPRESS_DB_PASSWORD: examplepass
        WORDPRESS_DB_NAME: exampledb
      volumes:
        - wordpress:/var/www/html
  
    db:
      image: postgres
      restart: always
      environment:
        POSTGRES_DB_NAME: exampledb
        POSTGRES_PASSWORD: examplepass
        POSTGRES_DB_USER: exampleuser
      volumes:
        - db:/var/lib/postgres
  
  volumes:
    wordpress:
    db:
  </code></pre>
  
  <p>Here is the logs:</p>
  
  <pre><code>dpress_1  | WordPress not found in /var/www/html - copying now...
  wordpress_1  | Complete! WordPress has been successfully copied to /var/www/html
  wordpress_1  | [02-Mar-2020 18:33:10 UTC] PHP Warning:  mysqli::__construct(): (HY000/2002): Connection refused in Standard input code on line 22
  wordpress_1  | MySQL Connection Error: (2002) Connection refused
  wordpress_1  |
  wordpress_1  | WARNING: unable to establish a database connection to 'db'
  wordpress_1  |   continuing anyways (which might have unexpected results)
  wordpress_1  |
  wordpress_1  | AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 172.25.0.3. Set the 'ServerName' directive globally to suppress this message
  wordpress_1  | AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 172.25.0.3. Set the 'ServerName' directive globally to suppress this message
  wordpress_1  | [Mon Mar 02 18:33:38.074477 2020] [mpm_prefork:notice] [pid 1] AH00163: Apache/2.4.38 (Debian) PHP/7.3.15 configured -- resuming normal operations
  wordpress_1  | [Mon Mar 02 18:33:38.074510 2020] [core:notice] [pid 1] AH00094: Command line: 'apache2 -D FOREGROUND'
  db_1         |
  db_1         | PostgreSQL Database directory appears to contain a database; Skipping initialization
  db_1         |
  db_1         | 2020-03-02 19:40:34.511 UTC [1] LOG:  starting PostgreSQL 12.2 (Debian 12.2-2.pgdg100+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 8.3.0-6) 8.3.0, 64-bit
  db_1         | 2020-03-02 19:40:34.512 UTC [1] LOG:  listening on IPv4 address "0.0.0.0", port 5432
  db_1         | 2020-03-02 19:40:34.512 UTC [1] LOG:  listening on IPv6 address "::", port 5432
  </code></pre>