Configuring Kubeflow with kfctl and kustomize

The basics of Kubeflow configuration with kfctl and kustomize

Kfctl is the Kubeflow command-line interface (CLI) that you can use to install and configure Kubeflow.

Kubeflow makes use of kustomize to help customize YAML configurations. With kustomize, you can traverse a Kubernetes manifest to add, remove, or update configuration options without forking the manifest. A manifest is a YAML file containing a description of the applications that you want to include in your Kubeflow deployment.

Overview of kfctl and kustomize

This section describes how kfctl works with kustomize to set up your Kubeflow deployment.

The Kubeflow deployment process

Kfctl is the Kubeflow CLI that you can use to set up a Kubernetes cluster with Kubeflow installed, or to deploy Kubeflow to an existing Kubernetes cluster. See the Kubeflow getting-started guide for installation instructions based on your deployment scenario.

The kfctl deployment process includes the following commands:

  • kfctl build - (Optional) Creates configuration files defining the various resources in your deployment but does not deploy Kubeflow. You only need to run kfctl build if you want to edit the resources before running kfctl apply.
  • kfctl apply - Creates or updates the resources.
  • kfctl delete - Deletes the resources.

Specifying a configuration file when initializing your deployment

When you install Kubeflow, the deployment process uses one of a few possible YAML configuration files to bootstrap the configuration. You can see all the configuration files on GitHub.

As an example, this guide uses the kfctl_k8s_istio.yaml configuration. For more details about this configuration, see the kfctl_k8s_istio deployment guide.

Typically, you specify the configuration file with a -f <config-file> parameter when you run kfctl build or kfctl apply. The following example uses kfctl build:

# Set KF_NAME to the name of your Kubeflow deployment. You also use this
# value as directory name when creating your configuration directory.
# For example, your deployment name can be 'my-kubeflow' or 'kf-test'.
export KF_NAME=<your choice of name for the Kubeflow deployment>

# Set the path to the base directory where you want to store one or more 
# Kubeflow deployments. For example, /opt/.
# Then set the Kubeflow application directory for this deployment.
export BASE_DIR=<path to a base directory>
export KF_DIR=${BASE_DIR}/${KF_NAME}

# Set the URI of the configuration file to use when deploying Kubeflow. 
# For example:
export CONFIG_URI="https://raw.githubusercontent.com/kubeflow/manifests/v1.0-branch/kfdef/kfctl_k8s_istio.v1.0.1.yaml"

# Create your Kubeflow configurations:
mkdir -p ${KF_DIR}
cd ${KF_DIR}
kfctl build -V -f ${CONFIG_URI}

Kfctl has now built the configuration files in your Kubeflow application directory (see below) but has not yet deployed Kubeflow. To complete the deployment, run kfctl apply. See the next section on applying the configuration.

Applying the configuration to your Kubeflow cluster

When you first run kfctl build or kfctl apply, kfctl creates a local version of the YAML configuration file, which you can further customize if necessary.

Follow these steps to apply the configurations to your Kubeflow cluster:

  1. Set an environment variable pointing to your local configuration file. For example, this guide uses the kfctl_k8s_istio.v1.0.1.yaml configuration. If you chose a different configuration in the previous step, you must change the file name to reflect your configuration:

    export CONFIG_FILE=${KF_DIR}/kfctl_k8s_istio.v1.0.1.yaml
    
  2. Apply the configurations:

    kfctl apply -V -f ${CONFIG_FILE}
    

Your Kubeflow directory layout

Your Kubeflow application directory is the directory where you choose to store your Kubeflow configurations during deployment. This guide refers to the directory as ${KF_DIR}. The directory contains the following files and directories:

  • ${CONFIG_FILE} is a YAML file that stores your primary Kubeflow configuration in the form of a KfDef Kubernetes object.

    • This file is a copy of the GitHub-based configuration YAML file that you used when deploying Kubeflow.
    • When you first run kfctl build or kfctl apply, kfctl creates a local version of the configuration file at ${CONFIG_FILE}, which you can further customize if necessary.
    • The YAML defines each Kubeflow application as a kustomize package.
  • <platform-name>_config is a directory that contains configurations specific to your chosen platform or cloud provider. For example, gcp_config or aws_config. This directory may or may not be present, depending on your setup.

    • The directory is created when you run kfctl build or kfctl apply.
    • To customize these configurations, you can modify parameters in your ${CONFIG_FILE}, and then run kfctl apply to apply the configuration to your Kubeflow cluster.
  • kustomize is a directory that contains Kubeflow application manifests. That is, the directory contains the kustomize packages for the Kubeflow applications that are included in your deployment.

    • The directory is created when you run kfctl build or kfctl apply.
    • To customize these configurations, you can modify parameters in your ${CONFIG_FILE}, and then run kfctl apply to apply the configuration to your Kubeflow cluster.

How your configuration is generated

The content of your ${CONFIG_FILE} is the result of running kustomize on the base and overlay kustomization.yaml files in the Kubeflow manifests. The overlays reflect the configuration file that you specify when running kfctl build or kfctl apply.

Below are some examples of configuration files:

  • kfctl_k8s_istio.yaml to install Kubeflow on an existing Kubernetes cluster.
  • kfctl_istio_dex.yaml to install Kubeflow on an existing Kubernetes cluster with Dex and Istio for authentication.
  • kfctl_gcp_iap.yaml to create a Google Kubernetes Engine (GKE) cluster with Kubeflow using Cloud Identity-Aware Proxy (Cloud IAP) for access control.

The kustomize package manager in kfctl uses the information in your ${CONFIG_FILE} to traverse the directories under the Kubeflow manifests and to create kustomize build targets based on the manifests.

Installing kustomize

Make sure that you have the minimum required version of kustomize: 2.0.3 or later.

  1. Follow the kustomize installation guide, choosing the relevant options for your operating system. For example, if you’re on Linux:

    • Set some variables for the operating system:

      export opsys=linux
      
    • Download the kustomize binary:

      curl -s https://api.github.com/repos/kubernetes-sigs/kustomize/releases |\
      grep browser_download |\
      grep download/kustomize |\
      grep -m 1 $opsys |\
      cut -d '"' -f 4 |\
      xargs curl -O -L
      
    • Move the binary:

      mkdir -p ${HOME}/bin
      mv kustomize_*_${opsys}_amd64 ${HOME}/bin/kustomize
      chmod u+x ${HOME}/bin/kustomize
      
  2. Include the kustomize command in your path:

      export PATH=$PATH:${HOME}/bin/kustomize
    

Modifying configuration before deployment

Kustomize lets you customize raw, template-free YAML files for multiple purposes, leaving the original YAML untouched and usable as is.

You can use the following command to build and apply kustomize directories:

kustomize build <kustomization_directory> | kubectl apply -f -

The Kubeflow manifests repo contains kustomize build targets, each with a base directory. You can use kustomize to generate YAML output and pass it to kfctl. You can also make changes to the kustomize targets in the manifests repo as needed.

Modifying the configuration of an existing deployment

To customize the Kubeflow resources running within the cluster, you can modify parameters in your ${CONFIG_FILE} file. Then re-run kfctl apply.

For example, to modify settings for the Spartakus usage reporting tool within your Kubeflow deployment:

  1. Edit the configuration file at ${CONFIG_FILE}.

  2. Find and replace the parameter values for spartakus to suit your requirements:

    - kustomizeConfig:
        parameters:
        - initRequired: true
            name: usageId
            value: <randomly-generated-id>
        - initRequired: true
            name: reportUsage
            value: "true"
        repoRef:
            name: manifests
            path: common/spartakus
        name: spartakus
    
  3. Regenerate and deploy your Kubeflow resources:

    cd ${KF_DIR}
    kfctl apply -V -f ${CONFIG_FILE}
    

More examples

For examples of customizing your deployment, see the guide to customizing Kubeflow on GKE.

For information about how Kubeflow uses Spartakus, see the guide to usage reporting.

More about kustomize

Below are some useful kustomize terms, from the kustomize glossary:

  • base: A combination of a kustomization and resource(s). Bases can be referred to by other kustomizations.

  • kustomization: Refers to a kustomization.yaml file, or more generally to a directory containing the kustomization.yaml file and all the relative file paths that the YAML file references.

  • overlay: A combination of a kustomization that refers to a base, and a patch. An overlay may have multiple bases.

  • patch: General instructions to modify a resource.

  • resource: Any valid YAML file that defines an object with a kind and a metadata/name field.

  • target: The argument to kustomize build. For example, kustomize build $TARGET. A target must be a path or a URL to a kustomization. A target can be a base or an overlay.

  • variant: The outcome of applying an overlay to a base.

Read more about kustomize in the kustomize documentation.