> ## Documentation Index
> Fetch the complete documentation index at: https://coollabstechnologiesbt.mintlify.site/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Docker Compose

> A guide on how to use Docker Compose deployments with Coolify.

If you are using `Docker Compose` based deployments, you need to understand how Docker Compose works with Coolify.

In all cases the Docker Compose (`docker-compose.y[a]ml`) file is the single source of truth.

## Defining environment variables

You have the following compose file:

```yaml
version: "3.8"

services:
  db:
    image: adminer
    environment:
      TEST: ${TEST}
```

And you define `TEST` and `ANOTHERTEST` environment variables inside Coolify, only `TEST` will be used, as Coolify cannot determine where to add `ANOTHERTEST` environment variable.

So if you want to use `ANOTHERTEST` environment variable, you need to add it to the compose file.

```yaml
version: "3.8"

services:
  db:
    image: adminer
    environment:
      TEST: ${TEST}
      ANOTHERTEST: ${ANOTHERTEST}
```

## Raw Docker Compose Deployment

You can set with docker compose build pack to deploy your compose file directly without most of Coolify's magic. It is called `Raw Compose Deployment`.

<Tip>
  This is for advanced users. If you are not familiar with Docker Compose, we do
  not recommend this method.
</Tip>

### What is still set?

Coolify will still add the following labels (if they are not set) to your application:

```yaml
labels:
  - coolify.managed=true
  - coolify.applicationId=5
  - coolify.type=application
```

### What to set?

To use Coolify's Proxy (Traefik), you need to set the following labels to your application:

```yaml
labels:
  - traefik.enable=true
  - "traefik.http.routers.<unique_router_name>.rule=Host(`coolify.io`) && PathPrefix(`/`)"
  - traefik.http.routers.<unique_router_name>.entryPoints=http
```

## Connect to Predefined Networks

By default, each compose stack is deployed to a separate network, with the name of your resource uuid. This will allow to each service in your stack to communicate with each other.

But in some cases, you would like to communicate with other resources in your account. For example, you would like to connect your application to a database, which is deployed in another stack.

To do this you need to enable `Connect to Predefined Network` option on your `Service Stack` page, but this will make the internal Docker DNS not work as expected.

Here is an example. You have a stack with a `postgres` database and a `laravel` application. Coolify will rename your `postgres` stack to `postgres-<uuid>` and your `laravel` stack to `laravel-<uuid>` to prevent name collisions.

If you set `Connect to Predefined Network` option on your `laravel` stack, your `laravel` application will be able to connect to your `postgres` database, but you need to use the `postgres-<uuid>` as your `DB_HOST` environment variable.