Install ncclient python package for junos switches on ansible 2.3+

This package is required on the ansible control host, and is used by the
ansible-connection process to access the switches via a persistent SSH
connection. It must be installed in the kayobe virtual environment.

ansible/roles/junos-switch/tasks/main.yml

@@ -3,6 +3,8 @@
 # not seem to be possible to use ansible_python_interpreter in combination with
 # delegate_to. This should be investigated in future as modification of system
 # packages via pip is not ideal.
+
+# For ansible 2.2, Juniper specific python packages are required.
 - name: Ensure python dependencies are installed
   pip:
     name: "{{ item }}"
@@ -10,8 +12,20 @@
   with_items:
     - junos-eznc
     - jxmlease
+  when: ansible_version | version_compare('2.3', 'lt')
   become: True
 
+# For ansible 2.3+, only the NETCONF client ncclient is required. This must be
+# installed on the ansible control host where the ansible-connection subprocess
+# is executed.
+- name: Ensure python dependencies are installed
+  local_action:
+    module: pip
+    name: ncclient
+    virtualenv: "{{ lookup('env', 'VIRTUAL_ENV') | default(omit, true) }}"
+  when: ansible_version | version_compare('2.3', 'ge')
+  become: "{{ lookup('env', 'VIRTUAL_ENV') == None }}"
+
 - name: Ensure Juniper switches are configured
   junos_config:
     provider: "{{ junos_switch_provider }}"