roles/nginx: Add pre and post hooks for Let's Encrypt on Ubuntu 20.04

Certbot will run any executables in the pre and post directories
during certificate renewal.

roles/nginx/files/start-nginx.sh

@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+
+/bin/systemctl start nginx

roles/nginx/files/stop-nginx.sh

@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+
+/bin/systemctl stop nginx

roles/nginx/tasks/letsencrypt.yml

@@ -216,8 +216,16 @@
 
 # On Ubuntu 20.04 it is no longer recommended/supported to use the standalone
 # certbot-auto so I guess we need to use the one from the repositories.
-- name: Install certbot (Ubuntu 20.04)
+- block:
+  - name: Install certbot (Ubuntu 20.04)
     apt: name=certbot state=present update_cache=yes
+
+  - name: Copy certbot post and pre hooks for nginx
+    copy: src={{ item.src }} dest={{ item.dest }} owner=root group=root mode=0755
+    with_items:
+      - { src: 'stop-nginx.sh', dest: '/etc/letsencrypt/renewal-hooks/post/stop-nginx.sh' }
+      - { src: 'start-nginx.sh', dest: '/etc/letsencrypt/renewal-hooks/post/start-nginx.sh' }
+
   when: ansible_distribution == 'Ubuntu' and ansible_distribution_version is version('20.04', '==')
   tags: letsencrypt