r/k8s-worker: Install iSCSI/NFS client tools

We don't want the iSCSI and NFS client tools to be installed on control
plane nodes.  Let's move this task to the _k8s-worker_ role so it will
only apply to worker nodes.

roles/k8s-worker/tasks/main.yml

@@ -1,3 +1,27 @@
+- name: ensure required packages are installed
+  package:
+    name:
+    # Required for Longhorn RWO volumes
+    - iscsi-initiator-utils
+    # Required for Longhorn RWX volumes
+    - nfs-utils
+    state: present
+  tags:
+  - install
+
+- name: ensure iscsi socket is enabled
+  systemd:
+    name: iscsid.socket
+    enabled: true
+  tags:
+  - service
+- name: ensure iscsi socket is active
+  systemd:
+    name: iscsid.socket
+    state: started
+  tags:
+  - service
+
 - name: flush handlers
   meta: flush_handlers
 

roles/kubelet/tasks/main.yml

@@ -112,16 +112,3 @@
     enabled: true
   tags:
   - service
-
-- name: ensure iscsi socket is enabled
-  systemd:
-    name: iscsid.socket
-    enabled: true
-  tags:
-  - service
-- name: ensure iscsi socket is active
-  systemd:
-    name: iscsid.socket
-    state: started
-  tags:
-  - service

roles/kubelet/vars/main.yml

@@ -6,7 +6,3 @@ kubernetes_common_packages:
 - ebtables
 - ethtool
 - iproute-tc
-# Required for Longhorn RWO volumes
-- iscsi-initiator-utils
-# Required for Longhorn RWX volumes
-- nfs-utils