Readme updates for helm chart local run

chart/README.md

 Chart for the View Server (VS) bundling all services
 
+All the commands must be ran from the charts folder. Must have `kubectl` and `helm` utilities and one of `k3s` or `minikube` clusters. The following commands also use `yq`, which is `jq`, but for yaml (`python3 -m pip install yq`). The guide also assumes everything runs in the default namespace.
+
 Useful commands:
 
 ```bash
 helm dependency update
 
 helm template testing . --output-dir ../tmp/ -f values.yaml
+```
+
+The template command outputs the rendered yaml files for debugging and checking.
+
+## Installing chart locally [DRAFT]
+
+In order to test the services together, here's a way to install the chart locally in your `k3s`/`minicube`. This install is based on the helm values in the eoepca repo and customizes them.
+
+### Prerequisites
+
+When running k3s and minikube in docker, the paths doesn't refer to your machine, but the docker container where k3s runs. The following display how to setup each solution.
+#### Minikube
+Minikube needs to be started with the following:
+
+```bash
+minikube start --mount-string /home/$user/:/minikube-host/
+minikube addons enable ingress
+```
+
+Here the full home directory is bound to the cluster at `/minikube-host` in order to bind mounts necessary for development. Also the ingress addon is enabled.
+
+#### k3s
+k3s is also started creating with specifying a volume
+
+``` bash
+k3s cluster create --volume /home/$user/:/k3s-host/
+```
 
+Here the full home directory is bound to the cluster at `/k3s-host` in order to bind mounts necessary for development.
+
+#### values.yaml
+The values yaml file should be setup with:
+
+```bash
+cat ~/path/to/eoepca/system/clusters/develop/resource-management/hr-data-access.yaml | yq .spec.values -y > /tmp/values.yaml
+```
+
+#### Persistent volume claims
+For the services to start, you're going to need the pvcs as below. Create a file `pvc.yaml` and run `kubectl apply -f pvc.yaml`
+```yaml
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: data-access-db
+  namespace: <your-namespace>
+spec:
+  accessModes:
+    - ReadWriteOnce
+  storageClassName: local-path # this should be `standard` for minikube
+  resources:
+    requests:
+      storage: 2Gi
+---
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: data-access-redis
+  namespace: <your-namespace>
+spec:
+  accessModes:
+    - ReadWriteOnce
+  storageClassName: local-path # this should be `standard` for minikube
+  resources:
+    requests:
+      storage: 2Gi
+```
+
+### Deploying the stack
+
+Install:
+```bash
+helm install test . --values /tmp/values.yaml
 ```
 
+Upgrade with overrides values:
+```bash
+helm upgrade test . --values /tmp/values.yaml --values your-values-override-file.yaml>
+```
+
+If you specify multiple values files, helm will merge them together. [You can even delete keys by setting them to `null` in the override file a](https://helm.sh/docs/chart_template_guide/values_files/) .
+
+A useful override is to set the ingress host e.g. to nip.io:
+```yaml
+ingress:
+  enabled: true
+  annotations:
+    kubernetes.io/ingress.class: nginx
+    nginx.ingress.kubernetes.io/proxy-read-timeout: '600'
+    nginx.ingress.kubernetes.io/enable-cors: 'true'
+    # cert-manager.io/cluster-issuer: letsencrypt
+  hosts:
+    - host: data-access.<IP-ADDRESS>.nip.io
+```
 
+Where `<IP-ADDRESS>` is one of
+
+* 127.0.0.1
+* Output of `minikube ip`
+
+You might also want to reduce the number of replicas:
+```yaml
+renderer:
+  replicaCount: 1
+```
+
+For development, it's useful to mount the code as volume. This cannot just be done via a values override since this customization option is not present in the chart template.
+
+When using k3s & minikube, it's enough to define a volume like this:
+
+```yaml
+  volumes:
+    - name: eoxserver
+      hostPath:
+        path: /<app>-host/path/to/eoxserver
+        type: DirectoryOrCreate
+```
+where `app` is `k3s` or `minikube` and a `volumeMount` for the container:
+
+```yaml
+  volumeMounts:
+    - mountPath: /usr/local/lib/python3.8/dist-packages/eoxserver/
+      name: eoxserver
+```
+
+# Useful overrides
+For now, these can be added to their respective templates `.yaml` files for development. Make sure not to commit them to the repo and have them only locally changed.
+
+Alternatively, these can be added to the file output of the `helm templates` command and upgraded with the `helm upgrade` command.  
+
+## Registrar
+
+```yaml
+volumes:
+  - name: registrar
+    hostPath:
+      path: /minikube-host/path/to/vs/core/registrar/
+      type: DirectoryOrCreate
+  - name: instance-registrar
+    hostPath:
+      path: /minikube-host/path/to/eoxserver/instances/registrar/
+      type: DirectoryOrCreate
+  - name: eoxserver-registrar
+    hostPath:
+      path: /minikube-host/path/to/eoxserver/eoxserver/ # important to bind to the eoxserver directory which is inside the eoxserver repo
+      type: DirectoryOrCreate
+
+volumeMounts:
+  - name: instance-registrar
+    mountPath: >-
+      /var/www/
+  - name: eoxserver-registrar
+    mountPath: >-
+      /usr/local/lib/python3.8/dist-packages/eoxserver/
+  - name: registrar
+    mountPath: >-
+      /usr/local/lib/python3.8/dist-packages/registrar-1.2.0-py3.8.egg/registrar/
+```
+
+## Renderer
+
+```yaml
+volumes:
+  - name: eoxserver-renderer
+    hostPath:
+      path: /minikube-host/path/to/eoxserver/eoxserver/ # important to bind to the eoxserver directory which is inside the eoxserver repo
+      type: DirectoryOrCreate
+  - name: instance-renderer
+    hostPath:
+      path: /minikube-host/path/eoxserver/instances/renderer/
+      type: DirectoryOrCreate
+
+volumeMounts:
+  - name: eoxserver-renderer
+    mountPath: >-
+      /usr/local/lib/python3.8/dist-packages/eoxserver/
+  - name: instance-renderer
+    mountPath: >-
+      /var/www/
+```
+
+## Client
+
+&#35; TODO: fill in the client overrides
+
+## Preprocessor
+
+&#35; TODO: fill in the preprocessor overrides
+
+## Ingestor
+
+&#35; TODO: fill in the ingestor overrides
 ## Publishing chart
 
 Currently this approach does not work 100% such repos cannot be declared [in dependencies of other charts](https://github.com/helm/helm/issues/6593)
 
 
 ```bash
-
 helm registry login registry.gitlab.eox.at
 helm chart save . registry.gitlab.eox.at/esa/prism/vs/chart
 helm chart push registry.gitlab.eox.at/esa/prism/vs/chart:0.1.0-beta.1
 ```
+