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Preparing the Setup

Conceptually, all Gardener components are designated to run inside as a Pod inside a Kubernetes cluster. The API server extends the Kubernetes API via the user-aggregated API server concepts. However, if you want to develop it, you may want to work locally with the Gardener without building a Docker image and deploying it to a cluster each and every time. That means that the Gardener runs outside a Kubernetes cluster which requires providing a Kubeconfig in your local filesystem and point the Gardener to it when starting it (see below).

Further details could be found in

  1. Principles of Kubernetes, and its components
  2. Kubernetes Development Guide
  3. Architecture of Gardener

This setup is based on minikube, a Kubernetes cluster running on a single node. Docker for Desktop and kind are also supported.

Installing Golang environment

Install latest version of Golang. For MacOS you could use Homebrew:

brew install golang

For other OS, please check Go installation documentation.

Installing kubectl and helm

As already mentioned in the introduction, the communication with the Gardener happens via the Kubernetes (Garden) cluster it is targeting. To interact with that cluster, you need to install kubectl. Please make sure that the version of kubectl is at least v1.11.x.

On MacOS run

brew install kubernetes-cli

Please check the kubectl installation documentation for other OS.

You may also need to develop Helm charts or interact with Tiller using the Helm CLI:

On MacOS run

brew install kubernetes-helm

On other OS please check the Helm installation documentation.

Installing git

We use git as VCS which you need to install.

On MacOS run

brew install git

On other OS, please check the Git installation documentation.

Installing openvpn

We use OpenVPN to establish network connectivity from the control plane running in the Seed cluster to the Shoot’s worker nodes running in private networks. To harden the security we need to generate another secret to encrypt the network traffic (details). Please install the openvpn binary. On MacOS run

brew install openvpn
export PATH=$(brew --prefix openvpn)/sbin:$PATH

On other OS, please check the OpenVPN downloads page.

Installing Minikube

You’ll need to have minikube installed and running.

Note: Gardener is working only with self-contained kubeconfig files because of security issue. You can configure your minikube to create self-contained kubeconfig files via:

minikube config set embed-certs true

Alternatively, you can also install Docker for Desktop and kind.

In case you want to use the “Docker for Mac Kubernetes” or if you want to build Docker images for the Gardener you have to install Docker itself. On MacOS, please use Docker for MacOS which can be downloaded here.

On other OS, please check the Docker installation documentation.

Installing iproute2

iproute2 provides a collection of utilities for network administration and configuration.

On MacOS run

brew install iproute2mac

Installing yaml2json and jq

go get -u
brew install jq

[MacOS only] Install GNU core utilities

When running on MacOS you have to install the GNU core utilities:

brew install coreutils gnu-sed

This will create symbolic links for the GNU utilities with g prefix in /usr/local/bin, e.g., gsed or gbase64. To allow using them without the g prefix please put /usr/local/opt/coreutils/libexec/gnubin at the beginning of your PATH environment variable, e.g., export PATH=/usr/local/opt/coreutils/libexec/gnubin:$PATH.

[Windows] WSL2

Apart from Linux distributions and MacOS, the local gardener setup can also run on the Windows Subsystem for Linux 2.

While WSL1, plain docker for windows and various Linux distributions and local Kubernetes environments may be supported, this setup was verified with:

The Gardener repository and all the above-mentioned tools (git, golang, kubectl, …) should be installed in your WSL2 distro, according to the distribution-specific Linux installation instructions.

[Optional] Installing gcloud SDK

In case you have to create a new release or a new hotfix of the Gardener you have to push the resulting Docker image into a Docker registry. Currently, we are using the Google Container Registry (this could change in the future). Please follow the official installation instructions from Google.

Local Gardener setup

This setup is only meant to be used for developing purposes, which means that only the control plane of the Gardener cluster is running on your machine.

Get the sources

Clone the repository from GitHub.

git clone
cd gardener

Start the Gardener

:warning: Before you start developing, please ensure to comply with the following requirements:

  1. You have understood the principles of Kubernetes, and its components, what their purpose is and how they interact with each other.
  2. You have understood the architecture of Gardener, and what the various clusters are used for.

Start a local kubernetes cluster

For the development of Gardener you need some kind of Kubernetes cluster, which can be used as a “garden” cluster. I.e. you need a Kubernetes API server on which you can register a APIService Gardener’s own Extension API Server.
For this you can use a standard tool from the community to setup a local cluster like minikube, kind or the Kubernetes Cluster feature in Docker for Desktop.

However, if you develop and run Gardener’s components locally, you don’t actually a fully fledged Kubernetes Cluster, i.e. you don’t actually need to run Pods on it. If you want to use a more lightweight approach for development purposes, you can use the “nodeless Garden cluster setup” residing in hack/local-garden. This is the easiest way to get your Gardener development setup up and running.

Using the nodeless cluster setup

Setting up a local nodeless Garden cluster is quite simple. The only prerequisite is a running docker daemon. Just use the provided Makefile rules to start your local Garden:

make local-garden-up
Starting gardener-dev kube-etcd cluster..!
Starting gardener-dev kube-apiserver..!
Starting gardener-dev kube-controller-manager..!
Starting gardener-dev gardener-etcd cluster..!
namespace/garden created created created

This will start all minimally required components of a Kubernetes cluster (etcd, kube-apiserver, kube-controller-manager) and an etcd Instance for the gardener-apiserver as Docker containers.

To tear down the local Garden cluster and remove the Docker containers, simply run:

make local-garden-down

Using minikube

Alternatively, spin up a cluster with minikube with this command:

minikube start --embed-certs #  `--embed-certs` can be omitted if minikube has already been set to create self-contained kubeconfig files.
😄  minikube v1.8.2 on Darwin 10.15.3
🔥  Creating virtualbox VM (CPUs=2, Memory=2048MB, Disk=20000MB) ...
🏄  Done! Thank you for using minikube!

Prepare the Gardener

Now, that you have started your local cluster, we can go ahead and register the Gardener API Server. Just point your KUBECONFIG environment variable to the local cluster you created in the previous step and run:

make dev-setup
Found Minikube ...
namespace/garden created
namespace/garden-dev created
deployment.apps/etcd created
service/etcd created
service/gardener-apiserver created
service/gardener-controller-manager created
endpoints/gardener-apiserver created
endpoints/gardener-controller-manager created created created created

Optionally, you can switch off the Logging feature gate of Gardenlet to save resources:

sed -i -e 's/Logging: true/Logging: false/g' dev/20-componentconfig-gardenlet.yaml

The Gardener exposes the API servers of Shoot clusters via Kubernetes services of type LoadBalancer. In order to establish stable endpoints (robust against changes of the load balancer address), it creates DNS records pointing to these load balancer addresses. They are used internally and by all cluster components to communicate. You need to have control over a domain (or subdomain) for which these records will be created. Please provide an internal domain secret (see this for an example) which contains credentials with the proper privileges. Further information can be found here.

kubectl apply -f example/10-secret-internal-domain-unmanaged.yaml
secret/internal-domain-unmanaged created

Run the Gardener

Next, run the Gardener API Server, the Gardener Controller Manager (optionally), the Gardener Scheduler (optionally), and the Gardenlet in different terminal windows/panes using rules in the Makefile.

make start-apiserver
Found Minikube ...
I0306 15:23:51.044421   74536 plugins.go:84] Registered admission plugin "ResourceReferenceManager"
I0306 15:23:51.044523   74536 plugins.go:84] Registered admission plugin "DeletionConfirmation"
I0306 15:23:51.626836   74536 secure_serving.go:116] Serving securely on [::]:8443

(Optional) Now you are ready to launch the Gardener Controller Manager.

make start-controller-manager
time="2019-03-06T15:24:17+02:00" level=info msg="Starting Gardener controller manager..."
time="2019-03-06T15:24:17+02:00" level=info msg="Feature Gates: "
time="2019-03-06T15:24:17+02:00" level=info msg="Starting HTTP server on"
time="2019-03-06T15:24:17+02:00" level=info msg="Acquired leadership, starting controllers."
time="2019-03-06T15:24:18+02:00" level=info msg="Starting HTTPS server on"
time="2019-03-06T15:24:18+02:00" level=info msg="Found internal domain secret internal-domain-unmanaged for domain"
time="2019-03-06T15:24:18+02:00" level=info msg="Successfully bootstrapped the Garden cluster."
time="2019-03-06T15:24:18+02:00" level=info msg="Gardener controller manager (version 1.0.0-dev) initialized."
time="2019-03-06T15:24:18+02:00" level=info msg="ControllerRegistration controller initialized."
time="2019-03-06T15:24:18+02:00" level=info msg="SecretBinding controller initialized."
time="2019-03-06T15:24:18+02:00" level=info msg="Project controller initialized."
time="2019-03-06T15:24:18+02:00" level=info msg="Quota controller initialized."
time="2019-03-06T15:24:18+02:00" level=info msg="CloudProfile controller initialized."

(Optional) Now you are ready to launch the Gardener Scheduler.

make start-scheduler
time="2019-05-02T16:31:50+02:00" level=info msg="Starting Gardener scheduler ..."
time="2019-05-02T16:31:50+02:00" level=info msg="Starting HTTP server on"
time="2019-05-02T16:31:50+02:00" level=info msg="Acquired leadership, starting scheduler."
time="2019-05-02T16:31:50+02:00" level=info msg="Gardener scheduler initialized (with Strategy: SameRegion)"
time="2019-05-02T16:31:50+02:00" level=info msg="Scheduler controller initialized."

(Optional) Now you are ready to launch the Gardenlet.

make start-gardenlet
time="2019-11-06T15:24:17+02:00" level=info msg="Starting Gardenlet..."
time="2019-11-06T15:24:17+02:00" level=info msg="Feature Gates: HVPA=true, Logging=true"
time="2019-11-06T15:24:17+02:00" level=info msg="Acquired leadership, starting controllers."
time="2019-11-06T15:24:18+02:00" level=info msg="Found internal domain secret internal-domain-unmanaged for domain"
time="2019-11-06T15:24:18+02:00" level=info msg="Gardenlet (version 1.0.0-dev) initialized."
time="2019-11-06T15:24:18+02:00" level=info msg="ControllerInstallation controller initialized."
time="2019-11-06T15:24:18+02:00" level=info msg="Shoot controller initialized."
time="2019-11-06T15:24:18+02:00" level=info msg="Seed controller initialized."

:warning: The Gardenlet will handle all your seeds for this development scenario, although, for productive usage it is recommended to run it once per seed, see this document for more information. See the Appendix on how to configure the Seed clusters for the local development scenario.

Please checkout the Gardener Extensions Manager to install extension controllers - make sure that you install all of them required for your local development. Also, please refer to this document for further information about how extensions are registered in case you want to use other versions than the latest releases.

The Gardener should now be ready to operate on Shoot resources. You can use

kubectl get shoots
No resources found.

to operate against your local running Gardener API Server.

Note: It may take several seconds until the minikube cluster recognizes that the Gardener API server has been started and is available. No resources found is the expected result of our initial development setup.

Limitations of local development setup

You can run Gardener (API server, controller manager, scheduler, gardenlet) against any local Kubernetes cluster, however, your seed and shoot clusters must be deployed to a “real” provider. Currently, it is not possible to run Gardener entirely isolated from any cloud provider. We are planning to support a setup that can run completely locally (see this for details), however, it does not yet exist. This means that - after you have setup Gardener - you need to register an external seed cluster (e.g., one created in AWS). Only after that step you can start creating shoot clusters with your locally running Gardener.

Some time ago, we had a local setup based on VirtualBox/Vagrant. However, as we have progressed with the Extensibility epic we noticed that this implementation/setup does no longer fit into how we envision external providers to be. Moreover, it hid too many things and came with a bunch of limitations, making the development scenario too “artificial”:

  • No integration with machine-controller-manager.
  • The Shoot API Server is exposed via a NodePort. In a cloud setup a LoadBalancer would be used.
  • It was not possible to create Shoot clusters consisting of more than one worker node. Cluster auto-scaling therefore is not supported.
  • It was not possible to create two or more Shoot clusters in parallel.
  • The communication between the Seed and the Shoot Clusters uses VPN tunnel. In this setup tunnels are not needed since all components run on localhost.

Additional information

To make sure that a specific Seed cluster will be chosen, specify the .spec.seedName field (see here for an example Shoot manifest).

Please take a look at the example manifests folder to see which resource objects you need to install into your Garden cluster.


Configure Seed clusters for local development

When using the Gardenlet in a local development scenario with make start-gardenlet then the Gardenlet component configuration is setup with a seed selector that targets all available Seed clusters. However, a Seed resource needs to be configured to allow being reconciled by a Gardenlet which such a configuration.

When deploying the Gardenlet to reconcile only one Seed cluster (using component configuration .seedConfig), the Gardenlet either needs to be supplied with a kubeconfig for the particular Seed cluster, or acquires one via bootstrapping. Having said that, if the Gardenlet is configured to manage multiple Seed clusters based on a label selector, it needs to fetch the kubeconfig of each Seed cluster at runtime from somewhere. That is why the Seed resource needs to be configured with an additional secret reference that contains the kubeconfig of the Seed cluster.

Create a secret containing the base64 encoded kubeconfig of the Seed cluster (the scope of the permissions should be identical to the kubeconfig that the Gardenlet creates during bootstrapping - for now, cluster-admin privileges are recommended).

Create the secret in the Garden cluster:

apiVersion: v1
kind: Secret
  name: sweet-seed
  namespace: garden
type: Opaque
  kubeconfig: <base64-seed-kubeconfig>.

Adjust the Seed resource to reference the secret in spec.secretRef like so:

kind: Seed
  name: my-sweet-seed
    name: sweet-seed
    namespace: garden