allow installation using pip

tasks/install-with-pip.yml

@@ -0,0 +1,15 @@
+---
+- name: Install pip
+  package: name=python-pip state=present
+  when: certbot_install == 'pip'
+
+- name: Install pip3
+  package: name=python3-pip state=present
+  when: certbot_install == 'pip3'
+
+- name: Install Certbot.
+  pip: name="{{ certbot_package }}" state=present executable="{{ certbot_install }}"
+
+- name: Set Certbot script variable.
+  set_fact:
+    certbot_script: /usr/local/bin/certbot

tasks/main.yml

@@ -2,10 +2,13 @@
 - import_tasks: include-vars.yml
 
 - import_tasks: install-with-package.yml
-  when: not certbot_install_from_source
+  when: certbot_install == 'pkg' and not certbot_install_from_source | default(False)
 
 - import_tasks: install-from-source.yml
-  when: certbot_install_from_source
+  when: certbot_install == 'source' or certbot_install_from_source | default(False)
+
+- import_tasks: install-with-pip.yml
+  when: certbot_install in ['pip', 'pip3']
 
 - include_tasks: create-cert-standalone.yml
   with_items: "{{ certbot_certs }}"