Update documentation and argument descriptions

README.md

@@ -1,9 +1,81 @@
 [![Build Status](https://travis-ci.org/kubernetes-csi/node-driver-registrar.svg?branch=master)](https://travis-ci.org/kubernetes-csi/node-driver-registrar)
 # Node Driver Registrar
+Latest stable image: `quay.io/k8scsi/csi-node-driver-registrar:v1.0.1`
 
-A sidecar container that
+The node-driver-registrar is a sidecar container that registers the CSI driver using the
+[kubelet plugin registration mechanism](https://kubernetes.io/docs/concepts/extend-kubernetes/compute-storage-net/device-plugins/#device-plugin-registration).
+
+## CSI and Kubernetes Compatibility
+Min/Max CSI spec: 1.0
+
+Min Kubernetes version: 1.13
+
+For older versions, please refer to the [node-registrar
+repository](https://github.com/kubernetes-csi/driver-registrar)
+
+## Usage
+There are two UNIX domain sockets used by the node-driver-registrar:
+
+* Socket that registers the driver with kubelet. This socket is created by the
+  node-driver-registrar at
+  `/var/lib/kubelet/plugins_registry/<plugin>-reg.sock` on the Kubernetes node.
+* Socket that sidecar containers and the kubelet volume subsystem uses to
+  communicate with the CSI driver and make CSI calls. This socket is created by
+  CSI driver at `/var/lib/kubelet/plugins/<plugin>/csi.sock`. This is the socket
+  referenced by the `--csi-address` and `--kubelet-registration-path` arguments.
+
+### Required arguments
+
+* `--csi-address`: This is the path to the CSI driver's socket seen inside the
+  node-driver-registrar container.
+* `--kubelet-registration-path`: This is the path to the CSI driver's socket seen
+  by kubelet.
+* `KUBE_NODE_NAME` environment variable: This is the name of the Kubernetes Node.
+
+### Required permissions
+The node-driver-registrar does not interact with the Kubernetes API, so no RBAC
+rules are needed.
+
+It does, however, need to be able to mount hostPath volumes and have the file
+permissions to:
+* read from `/var/lib/kubelet/plugins/<plugin>/`
+* write to `/var/lib/kubelet/plugins_registry/`
+
+### Example
+Here is an example sidecar spec in the driver DaemonSet. `<plugin>` should be replaced by
+the plugin's name.
+```
+      containers:
+        - name: csi-driver-registrar
+          image: quay.io/k8scsi/csi-node-driver-registrar:v1.0.1
+          args:
+            - "--csi-address=/csi/csi.sock"
+            - "--kubelet-registration-path=/var/lib/kubelet/plugins/<plugin>/csi.sock"
+          lifecycle:
+            preStop:
+              exec:
+                command: ["/bin/sh", "-c", "rm -rf /registration/<plugin> /registration/<plugin>-reg.sock"]
+          env:
+            - name: KUBE_NODE_NAME
+              valueFrom:
+                fieldRef:
+                  fieldPath: spec.nodeName
+          volumeMounts:
+            - name: plugin-dir
+              mountPath: /csi
+            - name: registration-dir
+              mountPath: /registration
+      volumes:
+        - name: registration-dir
+          hostPath:
+            path: /var/lib/kubelet/plugins_registry/
+            type: Directory
+        - name: plugin-dir
+          hostPath:
+            path: /var/lib/kubelet/plugins/<plugin>/
+            type: DirectoryOrCreate
+```
 
-1. Registers the containerized CSI driver with kubelet (in the future).
 
 ## Community, discussion, contribution, and support
 

cmd/node-driver-registrar/main.go

@@ -44,15 +44,10 @@ const (
 // Command line flags
 var (
 	connectionTimeout       = flag.Duration("connection-timeout", 1*time.Minute, "Timeout for waiting for CSI driver socket.")
-	csiAddress              = flag.String("csi-address", "/run/csi/socket", "Address of the CSI driver socket.")
-	kubeletRegistrationPath = flag.String("kubelet-registration-path", "",
-		`Enables Kubelet Plugin Registration service, and returns the specified path as "endpoint" in "PluginInfo" response.
-If this option is set, the driver-registrar expose a unix domain socket to handle Kubelet Plugin Registration,
-this socket MUST be surfaced on the host in the kubelet plugin registration directory (in addition to the CSI driver socket).
-If plugin registration is enabled on kubelet (kubelet flag KubeletPluginsWatcher is set), then this option should be set
-and the value should be the path of the CSI driver socket on the host machine.`)
-	showVersion = flag.Bool("version", false, "Show version.")
-	version     = "unknown"
+	csiAddress              = flag.String("csi-address", "/run/csi/socket", "Path of the CSI driver socket that the node-driver-registrar will connect to.")
+	kubeletRegistrationPath = flag.String("kubelet-registration-path", "", "Path of the CSI driver socket on the Kubernetes host machine.")
+	showVersion             = flag.Bool("version", false, "Show version.")
+	version                 = "unknown"
 
 	// List of supported versions
 	supportedVersions = []string{"1.0.0"}