Automatically infer bootstrap_os (#3498)

* Automatically infer bootstrap_os

* Rename bootstrap os to os_family

roles/bootstrap-os/tasks/main.yml

@@ -1,4 +1,25 @@
 ---
+- name: Fetch /etc/os-release
+  raw: cat /etc/os-release
+  register: os_release
+  changed_when: false
+
+- name: Set bootstrap_os
+  set_fact:
+    os_family: >-
+      {%- if 'Ubuntu' in os_release.stdout -%}
+      ubuntu
+      {%- elif 'Debian' in os_release.stdout -%}
+      debian
+      {%- elif 'CoreOS' in os_release.stdout -%}
+      coreos
+      {%- elif 'Fedora' in os_release.stdout -%}
+      fedora
+      {%- elif 'CentOS' in os_release.stdout -%}
+      centos
+      {%- elif 'OpenSUSE' in os_release.stdout -%}
+      opensuse
+      {% endif %}
 
 - include_tasks: bootstrap-ubuntu.yml
   when: os_family == "ubuntu"