Question 84043 in Docker Question posted in
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Connect from a docker container to a mysql database in another container

I would like to access mariadb in the db container from the app container with the following folder configuration, but it does not work with an error.

directory structure

.
├── app
│   └── Dockerfile
├── db
│   └── Dockerfile
└── docker-compose.yml

Code

app/Dockerfile

FROM debian:buster

RUN set -x 
    && apt-get update 
    && apt-get install --no-install-recommends --no-install-suggests -y 
        mariadb-client 
        vim

CMD [ "tail", "-f" ]

db/Dockerfile

FROM debian:buster

RUN set -x 
    && apt-get update 
    && apt-get install --no-install-recommends --no-install-suggests -y 
        mariadb-server 
        mariadb-client 
        vim

CMD service mysql start 
    && tail -f /dev/null

docker-compose.yml

version: "3.9"

services:
  app:
    build: ./app
    networks:
      - frontend

  db:
    build: ./db
    volumes:
      - db_data:/var/lib/mysql
    expose:
      - 3306
    networks:
      - frontend

networks:
  frontend:
    driver: bridge

volumes:
  db_data: {}

Execution Commands

I entered the app container and executed the following commands, but I get an error.

root@0e0ad0889639:/# mysql -h db -uroot
ERROR 2002 (HY000): Can't connect to MySQL server on 'db' (115)

root@0e0ad0889639:/# ping db
PING db (192.168.128.3) 56(84) bytes of data.
64 bytes from test_db_1.test_frontend (192.168.128.3): icmp_seq=1 ttl=64 time=0.104 ms
64 bytes from test_db_1.test_frontend (192.168.128.3): icmp_seq=2 ttl=64 time=0.142 ms

How can I connect?

Environment

❯ docker -v        
Docker version 20.10.12, build e91ed57

❯ docker-compose -v               
docker-compose version 1.29.2, build 5becea4c

❯ sw_vers
ProductName:    macOS
ProductVersion: 12.3
BuildVersion:   21E230
Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    The following method in db container solved the problem.

    1. database setting
    USE mysql;
GRANT ALL ON *.* TO 'root'@'%' identified by 'pass' WITH GRANT OPTION ;
GRANT ALL ON *.* TO 'root'@'localhost' identified by 'pass' WITH GRANT OPTION ;
FLUSH PRIVILEGES ;
    1. mysql config file setting
    echo "bind-address = app" >> etc/mysql/mariadb.conf.d/50-server.cnf

  2. 0

    As pointed out by comments, the default Debian MariaDB configures a bind-address to localhost. This is why the Docker Library mariadb image removes those configuration items.

    If all you want is a vim installed in your container maybe the following to gain all the benefits of a maintained and tested container image:

    db/Dockerfile

    FROM mariadb:10.6
ENV MARIADB_ROOT_PASSWORD=pass
RUN set -x 
    && apt-get update 
    && apt-get install --no-install-recommends --no-install-suggests -y 
        vim; 
    rm -rf /var/lib/apt/lists/*

    note small editors exist if you are interested.

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