Access Internal Database from Other Container on Coolify Published at 2025-01-21

Problems

Let me explain about the app first. I’m using Coolify to manage my apps on my own VM. I have 2 apps, the first one is backend app (containerized) and the second is MariaDB database (containerized).

Previously, whenever I wanted to access my database, I always use public IP address as host. Here is an example of my .env file

DB_HOST="123.123.123.123" #this is public ip address (accessible through internet)
DB_NAME=test
DB_USER=root
DB_PASSWORD=password
DB_PORT=3306

To make it more understandable and easy to read, look at this schema

As you can see, I always access my database through internet. This approach adds more latency, not secure, and if the internet goes down then the app won’t get fetch the data from that database.

Solutions

Change the IP address in DB_HOST as container name. Here is the expected schema

The problem now is how do we access the container from the other container? Because, as you can see here, coolify allows this database to accessible from other container (internally in coolify’s docker daemon).

Here is how to do that

1. First of all, you need to know the database’s container name. You can open the eye button in that MariaDB URL (internal) in the right side. You will see container name in the input element, like this

mysql://mariadb:sk7yRRLNfoDfzduhOOfJlAiJswjjMW0@a40k0sgowg0ckw4w448k4gko:3306/default

a40k0sgowg0ckw4w448k4gko is the container name

2. Then you need to setup a docker-compose file to allow your container access the coolify’s network. Here is the example

services:
  app:
    build:
      context: .
      dockerfile: Dockerfile
    networks:
      - coolify
    depends_on: []

networks:
  coolify:
    external: true

The Dockerfile part is depends on your needs, let’s just focus on networks part in this yml file. In this file, we are trying to access coolify network so that we can access other containers in coolify’s docker daemon

3. Last thing is, update your .env file like this

DB_HOST="a40k0sgowg0ckw4w448k4gko"
DB_NAME=test
DB_USER=root
DB_PASSWORD=password
DB_PORT=3306

After you’ve done setup your docker-compose, Dockerfile and coolify, your app will access database to the database container directly. This way will reduce latency, better security and if the internet is down, the app still can access the database.

Hope this help, thanks for stopping by.