System packages

Cortex uses Docker images to run workloads. These Docker images can be replaced with custom images based on Cortex images and augmented with your system packages and libraries. Your custom images need to be pushed to a container registry (e.g. Docker Hub, ECR, GCR) that can be accessed by your cluster.

See Image paths section in cortex config for all images that can be customized.

The example below demonstrates how to create a custom Docker image and configure Cortex to use it.

Create a custom image

Create a Dockerfile to build your custom image:

mkdir my-api && cd my-api && touch Dockerfile

Specify the base image you want to override followed by your customizations. The sample Dockerfile below inherits from Cortex's ONNX Serving image and installs the tree system package.

# Dockerfile
FROM cortexlabs/onnx-serve
RUN apt-get update \
&& apt-get install -y tree \
&& apt-get clean && rm -rf /var/lib/apt/lists/*

Build and push to a container registry

Create a repository to store your image:

# We create a repository in AWS ECR
export AWS_ACCESS_KEY_ID="***"
eval $(aws ecr get-login --no-include-email --region us-west-2)
aws ecr create-repository --repository-name=org/my-api --region=us-west-2
# take note of repository url

Build the image based on your Dockerfile and push to its repository in AWS ECR:

docker build . -t org/my-api:latest -t <repository_url>:latest
docker push <repository_url>:latest

Configure Cortex

Set the environment variable of the image to your my-api image repository url:

export CORTEX_IMAGE_ONNX_SERVE="<repository_url>:latest"
./ update

Use system packages in workloads

Cortex will use your image to launch ONNX serving workloads. You will have access to any customizations you made:

import subprocess
def pre_inference(sample, metadata):["tree"])