Docker Composer - Failing to run my webapp and mysql images

Question

I am new to docker and I am struggling to have the below scenario working: I have a working webapp image that uses alpine with tomcat 9 as a base image and a added my web app along with a series of user libraries.

Then I have a database image with mysql base, which I imported the database required by my web app to work.

If I run those images separately, they work fine, I have 100% access to them from the host system, no problem at all.

Now, I need them to communicate between themselves, it sounded to me this would be the easy part, but I am failing to make it work.

This is my composer.yml:

version: "3"
networks:
  uno:
services:
  mysql:
    image: mysql
    ports:
      - "3307:3306"
    networks:
      - uno
  web:
    image: unoerp9
    ports:
      - "8888:8080"
    depends_on:
      - mysql
    links:
      - mysql
    networks:
      - uno

The container starts ok: Check image here

But after some seconds, some erros appear on the log, and the mysql container stops:

mysql_1 | /usr/local/bin/docker-entrypoint.sh: running /docker-entrypoint-initdb.d/bck.sql

mysql_1 | mysql: [Warning] Using a password on the command line interface can be insecure.

mysql_1 | mbind: Operation not permitted

mysql_1 | mbind: Operation not permitted

mysql_1 | ERROR 1822 (HY000) at line 17806: Failed to add the foreign key constraint. Missing index for constraint 'fn_comissao_pagto_grupo_ibfk_1' in the referenced table 'vd_grupo_colaborador'

db_mysql_1 exited with code 1

Since there are erros with the mysql container, the webapp container trigger erros related to not being able to connect to the database, which is completely expected, so I am ommiting those.

Also, as the images work fine separately, I don't think it is some error related to how I built them, it must be something I am missing in my composer file. The expected result is to have both images running and communicating while I am able to access the web image through the browser (localhost:8888/) and the database (localhost:3307).

Any help?

Answer 1

You need to add a dependency for the web image on the mysql image by adding these lines

depends_on: - mysql

You can link the web image with the database image using:

links: - mysql

So you can use mysql as a hostname to connect to the database.

Try to use a specific mysql image such as mysql:5.7.22

This error mysql_1 | ERROR 1822 (HY000) at line 17806: Failed to add the foreign key constraint. Missing index for constraint 'fn_comissao_pagto_grupo_ibfk_1' in the referenced table 'vd_grupo_colaborador' is related to your mysql schema adn we cannot help with it without showing us the source code, if you can share it that would be great.

Answer 2

You can simplify your compose file considerably:

version: "3"
services:
  mysql:
    image: mysql:5.7
    volumes:
       - mysql-data:/var/lib/mysql
  web:
    image: unoerp9
    ports:
      - "8888:8080"

There is a network created automatically for every compose file and all containers are part of it. Within this network all ports of the containers are exposed. That means you can connect from your tomcat the database with mysql/my_database_name, you can omit the port there too because it is the default 3306.

I believe your MySQL error arises because the default image mysql:latest is version 8, which is probably not the same as the production system. Above I chose the tag 5.7 because it specifies the version to some degree so you wont get compatibility issues, but still take advantage of security updates from for example 5.7.22 (which @Mohsen suggested) to 5.7.23 that is the newest version at the moment.

I also added a volume to store the database data (in case that's helpful), so changes you make to the database are kept between restarts (docker-compose down) when the containers are deleted.