fix: update README.md for installtion add Dockerfile version and labels

Signed-off-by: Kevin Klopfenstein <kk@sudo-i.net>

Author: chifu1234

Dockerfile

@@ -1,13 +1,32 @@
-FROM scratch
+# renovate: datasource=docker depName=stagex/core-busybox versioning=loose
+ARG BUSYBOX_IMAGE=stagex/core-busybox:sx2026.03.0@sha256:4f3e3849acb54972e7c4f1d08c320526e0f8b314130bda68f83f821b02b4890b
 
-COPY --from=stagex/core-busybox /bin/mkdir /bin/mkdir
-COPY --from=stagex/core-busybox /usr/bin/mkdir /usr/bin/mkdir
+# Import the pinned image so we can COPY from it (workaround for --from + ARG).
+FROM ${BUSYBOX_IMAGE} AS busybox
 
-COPY --from=stagex/core-busybox /bin/cp /bin/cp
-COPY --from=stagex/core-busybox /usr/bin/cp /usr/bin/cp
+# Layout stage: temporarily bring in mkdir to create the directory tree.
+# This stage's tools are discarded; only the resulting /plugins tree is used.
+FROM scratch AS layout
 
+COPY --from=busybox /bin/mkdir /bin/mkdir
+COPY --from=busybox /usr/bin/mkdir /usr/bin/mkdir
 
 RUN ["/bin/mkdir", "-p", "/plugins/capsule"]
-
 COPY dist/main.js /plugins/capsule/main.js
 COPY package.json /plugins/capsule/package.json
+
+# Final image: minimal for use as an initContainer volume image.
+FROM scratch
+
+# cp is needed at runtime to support the documented pattern:
+#   command: ['cp', '-r', '/plugins/capsule', '/plugins']
+# mkdir is build-time only and not included here.
+COPY --from=busybox /bin/cp  /bin/cp
+COPY --from=busybox /usr/bin/cp /usr/bin/cp
+
+COPY --from=layout /plugins /plugins
+
+# OCI image labels (annotations / tags)
+LABEL org.opencontainers.image.source="https://github.com/projectcapsule/headlamp-plugin"
+LABEL org.opencontainers.image.description="Capsule multi-tenancy plugin for Headlamp"
+LABEL org.opencontainers.image.licenses="Apache-2.0"

README.md

@@ -26,11 +26,64 @@ The plugin brings first-class multi-tenancy awareness to the Headlamp UI, includ
 
 ### Using a Release (recommended)
 
-1. Download the latest `capsule-plugin-*.tar.gz` from the [Releases](https://github.com/projectcapsule/headlamp-plugin/releases) page.
+1. Download the latest `capsule-*.tar.gz` from the [Releases](https://github.com/projectcapsule/headlamp-plugin/releases) page.
 2. Open Headlamp.
 3. Go to **Settings → Plugins → Load plugin from file** and select the downloaded archive.
 4. The **Capsule** section will appear in the sidebar.
 
+### In-cluster
+
+#### Via init container (using our Docker image)
+
+Example patch for the Headlamp Deployment (our image includes `cp`):
+
+```yaml
+spec:
+  template:
+    spec:
+      initContainers:
+        - name: install-capsule-plugin
+          image: ghcr.io/projectcapsule/headlamp-plugin:vX.Y.Z
+          command: ['/bin/cp', '-r', '/plugins/capsule', '/target/plugins']
+          volumeMounts:
+            - name: plugins
+              mountPath: /target/plugins
+      containers:
+        - name: headlamp
+          volumeMounts:
+            - name: plugins
+              mountPath: /plugins
+      containers:
+        - name: headlamp
+          volumeMounts:
+            - name: plugins
+              mountPath: /plugins
+      volumes:
+        - name: plugins
+          emptyDir: {}
+```
+
+#### Using an image volume (Kubernetes 1.31+)
+
+
+```yaml
+spec:
+  template:
+    spec:
+      containers:
+        - name: headlamp
+          volumeMounts:
+            - name: plugins
+              mountPath: /plugins
+      volumes:
+        - name: plugins
+          image:
+            reference: ghcr.io/projectcapsule/headlamp-plugin:vX.Y.Z
+            pullPolicy: IfNotPresent
+```
+
+The image filesystem (containing `/plugins/capsule`) is mounted read-only at `/plugins`. This is the recommended approach when using a custom-built plugin image.
+
 ### Development / Hot Reload
 
 See the [Development](#development) section below.