Merge pull request #29 from inovex/readmePrePublish

docs: update README.md with installation instructions

Author: frittentheke

README.md

@@ -1,15 +1,70 @@
 # ExternalDNS - OpenStack Designate Webhook
 
 This is an [ExternalDNS provider](https://github.com/kubernetes-sigs/external-dns/blob/master/docs/tutorials/webhook-provider.md) for [OpenStack's Designate DNS server](https://docs.openstack.org/designate/latest/).
-This projects externalizes the yet in-tree [OpenStack Designate provider](https://github.com/kubernetes-sigs/external-dns/tree/master/provider/designate).
+This projects externalizes the in-tree [OpenStack Designate provider](https://github.com/kubernetes-sigs/external-dns/tree/master/provider/designate) and offers a way forward for bugfixes and new features as the in-tree providers have been [deprecated](https://github.com/kubernetes-sigs/external-dns?tab=readme-ov-file#status-of-in-tree-providers) and thus the code for OpenStack Designate will never leave the `Alpha` state.
 
-### 🌪 This project is in a very early stage and likely does not do what you expect!
+## Installation
+
+This webhook provider is run easiest as sidecar within the `external-dns` pod. This can be achieved using the official
+`external-dns` Helm chart and [its support for the `webhook` provider type]([https://kubernetes-sigs.github.io/external-dns/latest/charts/external-dns/#providers]).
+
+Setting the `provider.name` to `webhook` allows configuration of the
+`external-dns-openstack-webhook` via a few additional values:
+
+```yaml
+provider:
+  name: webhook
+  webhook:
+    image:
+      repository: ghcr.io/inovex/external-dns-openstack-webhook
+      tag: 1.0.0
+    extraVolumeMounts:
+      - name: oscloudsyaml
+        mountPath: /etc/openstack/
+    resources: {}
+    securityContext:
+      runAsUser: 1000
+```
+
+The referenced `extraVolumeMount` points to a `Secret` containing the `clouds.yaml` file, which provides the OpenStack Keystone credentials to the webhook provider. While it seems cumbersome to require a file instead of the commonly used `OS_*` environment variables, the use of a `clouds.yaml` file offers more structure, capabilities and allows for better validation.
+
+The following example is a basic example of such a file, using `openstack` as the cloud name (which is the default used by this webhook):
+
+```yaml
+clouds:
+  openstack:
+    auth:
+      auth_url: https://auth.cloud.example.com
+      application_credential_id: "TOP"
+      application_credential_secret: "SECRET"
+    region_name: "earth"
+    interface: "public"
+    auth_type: "v3applicationcredential"
+```
+
+An existing file can be converted into a Secret via kubectl:
+
+```shell
+kubectl create secret generic oscloudsyaml --namespace external-dns --from-file=clouds.yaml
+```
+
+and then also be added an extraVolume to within the `values.yaml` of external-dns:
+
+```yaml
+extraVolumes:
+  - name: oscloudsyaml
+    secret:
+      secretName: oscloudsyaml
+```
+
+## Bugs or feature requests
+
+This webhook certainly still contains bugs or lacks certain features.
+In such cases, please raise a GitHub issue with as much detail as possible. PRs with fixes and features are also very welcome.
 
 ## Development
 
-To run the webhook locally, you'll need to create a [clouds.yaml](https://docs.openstack.org/python-openstackclient/pike/configuration/index.html#clouds-yaml)
-file and put it in one of the standard-locations.
-Then set the cloud to be used in the `OS_CLOUD` environemnt variable.
+To run the webhook locally, you'll also require a [clouds.yaml](https://docs.openstack.org/python-openstackclient/pike/configuration/index.html#clouds-yaml) file in one of the standard-locations. Also the name of the entry to be used has be given via `OS_CLOUD` environment variable.
 You can then start the webhook server using:
 
 ```sh