description: "How to Use the Docker Compose Override File: In Docker Compose, an override file is a powerful feature that allows you to modify the default configuration provided by the main `docker-compose.yml` without the need to directly edit or duplicate the whole file."
In Docker Compose, an override file is a powerful feature that allows you to modify the default configuration provided by the main `docker-compose.yml` without the need to directly edit or duplicate the whole file. The primary use of the override file is for local development customizations, and Docker Compose merges the configurations of the `docker-compose.yml` and the `docker-compose.override.yml` files when you run `docker-compose up`.
Here's a quick guide on how to use the `docker-compose.override.yml`:
> Note: Please consult the `docker-compose.override.yml.example` for more examples
See the the official docker documentation for more info:
For example, if you want to make sure Docker can use your `librechat.yaml` file for [custom configuration](./custom_config.md), it would look like this:
```yaml
version: '3.4'
services:
api:
volumes:
- ./librechat.yaml:/app/librechat.yaml
```
Or, if you want to use a prebuilt image for the `api` service and expose MongoDB's port, your `docker-compose.override.yml` might look like this:
> Note: Be cautious with exposing ports like MongoDB to the public, as it can make your database vulnerable to attacks.
## Step 3: Apply the changes
To apply your configuration changes, simply run Docker Compose as usual. Docker Compose automatically takes into account both the `docker-compose.yml` and the `docker-compose.override.yml` files:
```bash
docker-compose up -d
```
If you want to invoke a build with the changes before starting containers:
```bash
docker-compose build
docker-compose up -d
```
## Step 4: Verify the changes
After starting your services with the modified configuration, you can verify that the changes have been applied using the `docker ps` command to list the running containers and their properties, such as ports.
## Important Considerations
- **Order of Precedence**: Values defined in the override file take precedence over those specified in the original `docker-compose.yml` file.
- **Security**: When customizing ports and publicly exposing services, always be conscious of the security implications. Avoid using defaults for production or sensitive environments.
By following these steps and considerations, you can easily and safely modify your Docker Compose configuration without altering the original `docker-compose.yml` file, making it simpler to manage and maintain different environments or local customizations.
