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kubeflow-controller

This repository implements a simple controller for watching Profile resources as defined with a CustomResourceDefinition (CRD).

Note: go-get or vendor this package as github.com/StatCan/kubeflow-controller.

This particular example demonstrates how to perform basic operations such as:

  • How to register a new custom resource (custom resource type) of type Profile using a CustomResourceDefinition.
  • How to create/get/list instances of your new resource type Profile.
  • How to setup a controller on resource handling create/update/delete events.

It makes use of the generators in k8s.io/code-generator to generate a typed client, informers, listers and deep-copy functions. You can do this yourself using the ./hack/update-codegen.sh script.

The update-codegen script will automatically generate the following files & directories:

  • pkg/apis/kubeflowcontroller/v1/zz_generated.deepcopy.go
  • pkg/generated/

Changes should not be made to these files manually, and when creating your own controller based off of this implementation you should not copy these files and instead run the update-codegen script to generate your own.

Details

The kubeflow controller uses client-go library extensively. The details of interaction points of the kubeflow controller with various mechanisms from this library are explained here.

Fetch kubeflow-controller and its dependencies

Like the rest of Kubernetes, kubeflow-controller has used godep and $GOPATH for years and is now adopting go 1.11 modules. There are thus two alternative ways to go about fetching this demo and its dependencies.

Fetch with godep

When NOT using go 1.11 modules, you can use the following commands.

go get -d github.com/StatCan/kubeflow-controller
cd $GOPATH/src/github.com/StatCan/kubeflow-controller
godep restore

When using go 1.11 modules

When using go 1.11 modules (GO111MODULE=on), issue the following commands --- starting in whatever working directory you like.

git clone https://github.com/statcan/kubeflow-controller.git
cd kubeflow-controller

Note, however, that if you intend to generate code then you will also need the code-generator repo to exist in an old-style location. One easy way to do this is to use the command go mod vendor to create and populate the vendor directory.

Purpose

This controller updates the state of Vault to allow access to secrets from OIDC users and from inside a profile's namespace.

Example object diagram

Running

Prerequisite: Since the kubeflow-controller uses apps/v1 deployments, the Kubernetes cluster version should be greater than 1.9.

# assumes you have a working kubeconfig, not required if operating in-cluster
go build -o kubeflow-controller .
./kubeflow-controller -kubeconfig=$HOME/.kube/config

# create a CustomResourceDefinition
kubectl create -f artifacts/examples/crd.yaml

# create a custom resource of type Profile
kubectl create -f artifacts/examples/example-profile.yaml

# check deployments created through the custom resource
kubectl get deployments

Use Cases

CustomResourceDefinitions can be used to implement custom resource types for your Kubernetes cluster. These act like most other Resources in Kubernetes, and may be kubectl apply'd, etc.

Some example use cases:

  • Provisioning/Management of external datastores/databases (eg. CloudSQL/RDS instances)
  • Higher level abstractions around Kubernetes primitives (eg. a single Resource to define an etcd cluster, backed by a Service and a ReplicationController)

Cleanup

You can clean up the created CustomResourceDefinition with:

    kubectl delete crd profiles.kubeflow.org