How to connect dockers with compose, mysql, and golang

Question

I have a database docker that we'll call mariadb and I also have an web docker that uses golang. What I'm trying to do is connect the two dockers using compose, but in my golang code, I have to know the database docker's ip address ahead of time.

Golang main.go:

db, err := sql.Open("mysql", 
"root:passsword@tcp(<should_be_database_docker_ip>:3306)/database")

Docker-compose.yml

version: '3'

services:
  web:
    image: web_docker
    ports:
      - "8080"
    depends_on:
      - database

  database:
    image: mariadb
    ports:
      - "3306"
    environment:
      - MYSQL_ROOT_PASSWORD=password
    volumes:
      - /data:/var/lib/mysql

Again for clarification, I cannot simply make the host be localhost because the database I'm using is in a docker and is usually something like 172.17.0.2 or .3 but sometimes it changes. Thank you!

Answer 1

You can just use your docker service name database, instead of container ip

UPD You also should share ports like

"3306:3306"

or ports will maps randomly

see output of

docker-compose ps

UPD2 according to mysql docker image doc you also need to define more environment variables, eg MYSQL_DATABASE