# Docker
source: https://docs.chalk.ai/docs/docker

## Customize the base image for your pipelines.

Chalk runs your feature pipelines on Docker images.
If your code relies only on your resolvers and data source definitions, you may
use Chalk's base image with no modification. If you require additional
dependencies, you can specify installation and management instructions.

You can specify build options on a per-environment basis,
and you can provide a default set of configuration for
environments that do not have explicit configuration values.

### Extra pip dependencies

Chalk can install extra dependencies with pip.
By default, Chalk looks for a file named requirements.txt in the base
of your project.

However, you can override this location or specify requirements
files per-environment in the chalk.yaml file located at the base
of your repo.

```
project: my-project-id
environments:
  default:
    runtime: python312
    requirements: ./requirements.txt
    dockerfile: Dockerfile
  prod:
    requirements: ./requirements-prod.txt
```

### Building your own image

You may have dependencies that cannot be expressed through pip.
For those dependencies, you need to customize the base image Chalk uses
to run your pipelines.
Chalk allows you to specify a custom Dockerfile
that will be used to build a base image for your deploys.

```
project: my-project-id
environments:
  default:
    dockerfile: ./Dockerfile
  prod:
    dockerfile: ./DockerfileProd
```

You build any Debian-based
image that you like, with a few requirements:

- python must be on the path
- pip must be on the path
- The Python version can be python310, python311, python312, python313, or python314
- There should be no folder or file at /app

Chalk is responsible for mounting your code into
the image, and for installing your requirements with pip.

### Python Version

The Python version for a Chalk project is set at the project level.
The version is set with the chalk.yml file in your project repo.
Chalk supports python310, python311, python312, python313, and python314 as values for runtime:

```
project: my-project-id
environments:
  default:
    runtime: python312
  prod:
    runtime: python311
```