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kinder

kinder is a tool designed for helping kubeadm contributors, by allowing them to create, delete and modify local clusters, and also execute actions, such as running the Kubernetes E2E suite.

kinder is a work in progress. Test it! Break it! Send feedback!

The exported logic in kinder packages can be a subject of change at any point in time, thus using kinder as a library is unsupported.

See the kinder roadmap for more information.

Prerequisites

Install git

Our source code is managed with git, to develop locally you will need to install git.

You can check if git is already on your system and properly installed with the following command:

git --version

Install Go

To work with kinder you will need Go.

Install or upgrade Go using the instructions for your operating system. You can check if Go is in your system with the following command:

go version

Working with Go modules requires at least 1.11.4 due to checksum bugs in lower versions.

Getting started

Clone the kubeadm repository:

git clone https://github.com/kubernetes/kubeadm.git

This will create a directory named 'kubeadm'. You will find a subdirectory named 'kinder'.

Then build kinder.

cd kubeadm/kinder
GO111MODULE=on go install

This will put kinder in $(go env GOPATH)/bin.

Usage

kinder is based on kind, so it is recommended to read the kind documentation first.

What makes kinder different, is the fact that it is designed for helping kubeadm contributors, so it provides a slightly different workflow that allows developers to take control of the cluster bootstrap process.

kinder workflow

See kind & kinder for a more detailed comparison between kind and kinder.

Prepare node-image & node-image variants

kind can be extremely efficient when the node image contains all the necessary artifacts.

kinder allows kubeadm contributors to exploit this feature by implementing the kinder build node-variant command, that takes a node-image and allows to build variants by:

  • Adding new pre-loaded images that will be made available on all nodes at cluster creation time
  • Replacing the kubeadm binary installed in the image, e.g. with a locally build version of kubeadm
  • Replacing the kubelet binary installed in the cluster, e.g. with a locally build version of kubelet
  • Adding a second Kubernetes version to be used for upgrade testing

e.g. if you want to test a kubeadm version already built locally:

kinder build node-variant \
    --base-image kindest/node:v1.13.4 \
    --image kindest/node:PR1234 \
    --with-kubeadm $working_dir/kubernetes/_output/local/bin/linux/amd64/kubeadm

see Prepare for tests for more details.

Create Nodes

By default kinder stops the cluster creation process before executing kubeadm init and kubeadm join; this will give you nodes ready for installing Kubernetes and more specifically:

  • The necessary prerequisites already installed on all nodes
  • In case of more than one control-plane node exists in the cluster, a pre-configured external load balancer

Additionally, the kinder create command gives you shortcuts for testing different Kubernetes cluster topologies without using the kind config file:

  • Flag --control-plane-nodes
  • Flag --worker-nodes

Similarly, kinder create command gives you also shortcuts for testing different kubeadm cluster configurations:

  • Flag --external-load-balancer
  • Flag --external-etcd

Work on Nodes

kinder do command is the kinder swiss knife. It allows to execute actions (repetitive tasks/sequence of commands) on one or more nodes. Available actions are

action Notes
kubeadm-config Creates /kind/kubeadm.conf files on nodes (this action is automatically executed during kubeadm-init or kubeadm-join) .
loadbalancer Update the load balancer configuration, if present (this action is automatically executed during kubeadm-init or kubeadm-join) .
kubeadm-init Executes the kubeadm-init workflow, installs the CNI plugin and then copies the kubeconfig file on the host machine.
manual-copy-certs Implement the manual copy of certificates to be shared across control-plane nodes (n.b. manual means not managed by kubeadm).
kubeadm-join Executes the kubeadm-join workflow both on secondary control plane nodes and on worker nodes.
kubeadm-upgrade Executes the kubeadm-upgrade workflow and upgrading K8s.
kubeadm-reset Executes the kubeadm-reset workflow on all the nodes.
cluster-info Returns a summary of cluster info
smoke-test Implements a non-exhaustive set of tests

kinder provides also kinder exec and kinder cp commands, a topology aware wrappers on docker exec and docker cp.

For more details please take a look at following how to guides:

or at the kinder reference