deploy: expose csi.sock outside of the cluster

Tools like csi-sanity and csc have to connect to the CSI driver. This
can be achieved by exposing the csi.sock as a TCP service with
forwarding handled by socat.

deploy/kubernetes-1.13/deploy-hostpath.sh

@@ -146,9 +146,9 @@ done
 # Wait until all pods are running. We have to make some assumptions
 # about the deployment here, otherwise we wouldn't know what to wait
 # for: the expectation is that we run attacher, provisioner,
-# snapshotter and hostpath plugin in the default namespace.
+# snapshotter, socat and hostpath plugin in the default namespace.
 cnt=0
-while [ $(kubectl get pods 2>/dev/null | grep '^csi-hostpath.* Running ' | wc -l) -lt 4 ] || ! kubectl describe volumesnapshotclasses.snapshot.storage.k8s.io 2>/dev/null >/dev/null; do
+while [ $(kubectl get pods 2>/dev/null | grep '^csi-hostpath.* Running ' | wc -l) -lt 5 ] || ! kubectl describe volumesnapshotclasses.snapshot.storage.k8s.io 2>/dev/null >/dev/null; do
     if [ $cnt -gt 30 ]; then
         echo "Running pods:"
         kubectl describe pods

deploy/kubernetes-1.13/hostpath/csi-hostpath-testing.yaml

@@ -0,0 +1,59 @@
+# WARNING: this is only for testing purposes. Do not install in a production
+# cluster.
+#
+# This exposes the hostpath's Unix domain csi.sock as a TCP port to the
+# outside world. The mapping from Unix domain socket to TCP is done
+# by socat.
+#
+# This is useful for testing with csi-sanity or csc.
+
+apiVersion: v1
+kind: Service
+metadata:
+  name: hostpath-service
+spec:
+  type: NodePort
+  selector:
+    app: csi-hostpath-socat
+  ports:
+  - port: 10000 # fixed port inside the pod, dynamically allocated port outside
+---
+kind: StatefulSet
+apiVersion: apps/v1
+metadata:
+  name: csi-hostpath-socat
+spec:
+  serviceName: "csi-hostpath-socat"
+  replicas: 1
+  selector:
+    matchLabels:
+      app: csi-hostpath-socat
+  template:
+    metadata:
+      labels:
+        app: csi-hostpath-socat
+    spec:
+      affinity:
+        podAffinity:
+          requiredDuringSchedulingIgnoredDuringExecution:
+          - labelSelector:
+              matchExpressions:
+              - key: app
+                operator: In
+                values:
+                - csi-hostpathplugin
+            topologyKey: kubernetes.io/hostname
+      containers:
+        - name: socat
+          image: alpine/socat:1.0.3
+          args:
+            - tcp-listen:10000,fork,reuseaddr
+            - unix-connect:/csi/csi.sock
+          volumeMounts:
+          - mountPath: /csi
+            name: socket-dir
+      volumes:
+        - hostPath:
+            path: /var/lib/kubelet/plugins/csi-hostpath
+            type: DirectoryOrCreate
+          name: socket-dir