chore: added readme

README.md

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+# volume-operator
+
+_Kubernetes controller/operator to manage Azure-backed volumes for Deployments._
+
+[![Build](https://github.com/PDOK/volume-operator/actions/workflows/build-and-publish-image.yml/badge.svg)](https://github.com/PDOK/volume-operator/actions/workflows/build-and-publish-image.yml)
+[![Lint (go)](https://github.com/PDOK/volume-operator/actions/workflows/lint-go.yml/badge.svg)](https://github.com/PDOK/volume-operator/actions/workflows/lint-go.yml)
+[![Go Report Card](https://goreportcard.com/badge/github.com/PDOK/volume-operator)](https://goreportcard.com/report/github.com/PDOK/volume-operator)
+[![GitHub license](https://img.shields.io/github/license/PDOK/volume-operator)](https://github.com/PDOK/volume-operator/blob/master/LICENSE)
+[![Docker Pulls](https://img.shields.io/docker/pulls/pdok/volume-operator.svg)](https://hub.docker.com/r/pdok/volume-operator)
+
+## Description
+
+This Kubernetes controller cq operator (an operator could be described as a specialized controller)
+automatically provisions Azure-backed persistent volumes for Deployments by watching ReplicaSets
+and creating the necessary storage resources based on annotations placed on the owning Deployment.
+
+The operator integrates with [azure-volume-populator](https://github.com/pdok/azure-volume-populator)
+to populate volumes from Azure Blob Storage. Instead of a Custom Resource Definition, configuration
+is expressed through annotations on the Deployment itself, making adoption straightforward without
+changes to existing manifests beyond adding the relevant annotations.
+
+The operator watches ReplicaSets and, for each active ReplicaSet belonging to an annotated Deployment,
+creates the following resources in the same namespace:
+
+* An `AzureVolumePopulator` CR, which instructs the azure-volume-populator to populate the volume
+  from a blob prefix in Azure Blob Storage
+* A `PersistentVolumeClaim` backed by the above populator and configured with the requested
+  storage class and capacity
+
+When a Deployment rolls out a new ReplicaSet (e.g. during a rolling update), the operator cleans up
+the `AzureVolumePopulator`, `PersistentVolumeClaim`, and old ReplicaSet belonging to the previous revision,
+preventing stale storage resources from accumulating in the cluster.
+
+### Annotations
+
+All annotations use the prefix `volume-operator.pdok.nl`. The following annotations are read from
+the **Deployment**:
+
+| Annotation | Required | Default | Description |
+|---|---|---|---|
+| `volume-operator.pdok.nl/resource-suffix` | yes | — | Name used for the created `AzureVolumePopulator` and `PersistentVolumeClaim` |
+| `volume-operator.pdok.nl/blob-prefix` | yes | — | Blob prefix in Azure Blob Storage to populate the volume from |
+| `volume-operator.pdok.nl/volume-path` | yes | — | Path inside the volume to populate |
+| `volume-operator.pdok.nl/storage-capacity` | no | `1Gi` | Size of the requested `PersistentVolumeClaim` |
+| `volume-operator.pdok.nl/storage-class-name` | no | `managed-premium-zrs` | Storage class to use for the `PersistentVolumeClaim` |
+
+## Run/usage
+
+```shell
+go build github.com/PDOK/volume-operator/cmd -o manager
+```
+
+or
+
+```shell
+docker build -t pdok/volume-operator .
+```
+
+```text
+USAGE:
+   <volume-controller-manager> [OPTIONS]
+
+OPTIONS:
+  -h, --help
+        Display these options.
+  --enable-http2
+        If set, HTTP/2 will be enabled for the metrics and webhook servers
+  --health-probe-bind-address string
+        The address the probe endpoint binds to. (default ":8081")
+  --kubeconfig string
+        Paths to a kubeconfig. Only required if out-of-cluster.
+        Alternatively use the KUBECONFIG environment variable.
+  --leader-elect
+        Enable leader election for controller manager. Enabling this will ensure there is only one active controller manager.
+  --metrics-bind-address string
+        The address the metrics endpoint binds to. Use :8443 for HTTPS or :8080 for HTTP, or leave as 0 to disable. (default "0")
+  --metrics-cert-key string
+        The name of the metrics server key file. (default "tls.key")
+  --metrics-cert-name string
+        The name of the metrics server certificate file. (default "tls.crt")
+  --metrics-cert-path string
+        The directory that contains the metrics server certificate.
+  --metrics-secure
+        If set, the metrics endpoint is served securely via HTTPS. Use --metrics-secure=false to use HTTP instead. (default true)
+  --webhook-cert-key string
+        The name of the webhook key file. (default "tls.key")
+  --webhook-cert-name string
+        The name of the webhook certificate file. (default "tls.crt")
+  --webhook-cert-path string
+        The directory that contains the webhook certificate.
+  --zap-devel
+        Development Mode defaults(encoder=consoleEncoder,logLevel=Debug,stackTraceLevel=Warn). Production Mode defaults(encoder=jsonEncoder,logLevel=Info,stackTraceLevel=Error) (default true)
+  --zap-encoder value
+        Zap log encoding (one of 'json' or 'console')
+  --zap-log-level value
+        Zap Level to configure the verbosity of logging. Can be one of 'debug', 'info', 'error', or any integer value > 0 which corresponds to custom debug levels of increasing verbosity
+  --zap-stacktrace-level value
+        Zap Level at and above which stacktraces are captured (one of 'info', 'error', 'panic').
+  --zap-time-encoding value
+        Zap time encoding (one of 'epoch', 'millis', 'nano', 'iso8601', 'rfc3339' or 'rfc3339nano'). Defaults to 'epoch'.
+
+OPTIONS can also be set via environment variables (with SCREAMING_SNAKE_CASE instead of kebab-case). CLI flags have precedence.
+```
+
+### Setup in the cluster
+
+This depends on your own way of maintaining your cluster config.
+Inspiration can be found in the [config](./config) dir
+which holds "kustomizations" to use with Kustomize.
+You could use `make install` for this.
+Please refer to the general documentation in the [kubebuilder book](https://kubebuilder.io) for more info.
+
+## Develop
+
+The project is written in Go and scaffolded with [kubebuilder](https://kubebuilder.io).
+
+### Running locally
+
+See [running and deploying the controller](https://kubebuilder.io/cronjob-tutorial/running) for details.
+
+### kubebuilder
+
+This project is scaffolded using Kubebuilder, to update the scaffolding:
+- Install the latest version of Kubebuilder on your machine;
+- Run: `kubebuilder alpha update --from-branch master`
+- This command will probably fail with the message that you should resolve merge conflicts and then run `make fmt vet <some other command>`. This is not a problem. Resolve the conflicts and run the command.
+
+### Linting
+
+Run `make lint` from the root of the project.
+
+## Misc
+
+### How to Contribute
+
+See [CONTRIBUTING.md](https://github.com/PDOK/.github/blob/master/CONTRIBUTING.md).
+
+### Contact
+
+Contacting the maintainers can be done through the issue tracker.
+