# Gardener Extension for centos OS


This controller operates on the [`OperatingSystemConfig`](https://github.com/gardener/gardener/blob/master/docs/proposals/01-extensibility.md#cloud-config-user-data-for-bootstrapping-machines) resource in the `extensions.gardener.cloud/v1alpha1` API group. It manages those objects that are requesting [Centos OS](https://www.centos.com/) configuration (`.spec.type=centos-tidb`).

```yaml
---
apiVersion: extensions.gardener.cloud/v1alpha1
kind: OperatingSystemConfig
metadata:
  name: pool-01-original
  namespace: default
spec:
  type: centos-tidb
  units:
    ...
  files:
    ...
```

Please find [a concrete example](example/operatingsystemconfig.yaml) in the `example` folder.

After reconciliation the resulting data will be stored in a secret within the same namespace (as the config itself might contain confidential data). The name of the secret will be written into the resource's `.status` field:

```yaml
...
status:
  ...
  cloudConfig:
    secretRef:
      name: osc-result-pool-01-original
      namespace: default
  command: /usr/bin/env bash <path>
  units:
  - docker-monitor.service
  - kubelet-monitor.service
  - kubelet.service
```

The secret has one data key `cloud_config` that stores the generation.

An example for a `ControllerRegistration` resource that can be used to register this controller to Gardener can be found [here](example/controller-registration.yaml).

This controller is implemented using the [`oscommon`](https://github.com/gardener/gardener/extensions/pkg/controller/operatingsystemconfig/oscommon/README.md) library for operating system configuration controllers.

Please find more information regarding the extensibility concepts and a detailed proposal [here](https://github.com/gardener/gardener/blob/master/docs/proposals/01-extensibility.md).

----

## How to start using or developing this extension controller locally

You can run the controller locally on your machine by executing `make start`. Please make sure to have the kubeconfig to the cluster you want to connect to ready in the `./dev/kubeconfig` file.
Static code checks and tests can be executed by running `make verify`. We are using Go modules for Golang package dependency management and [Ginkgo](https://github.com/onsi/ginkgo)/[Gomega](https://github.com/onsi/gomega) for testing.