Add exim role to base playbook

We want email to work.

Add a default value so that integration tests work - and update the
template so that if the value in the alias mapping is empty we don't
write out a half-formed alias.

Enable the epel repo on CentOS nodes in base-repos. This is done in
install_puppet.sh, but install_puppet.sh doesn't get run on ansible-only
nodes.

Change-Id: I68ad9f66c3b8672d9642c7764e50adac9cafdaf9

playbooks/base.yaml

@@ -8,3 +8,6 @@
 - hosts: "!disabled"
   roles:
     - base-server
+    - role: exim
+      aliases:
+        root: "{{ ','.join(sysadmins|default([])) }}"

playbooks/roles/base-repos/tasks/CentOS.yaml

@@ -0,0 +1,21 @@
+- name: Install epel-release
+  yum:
+    name: epel-release
+
+# there is a bug (rhbz#1261747) where systemd can fail to enable
+# services due to selinux errors after upgrade.  A work-around is
+# to install the latest version of selinux and systemd here and
+# restart the daemon for good measure after it is upgraded.
+- name: Install latest selinux-policy and systemd
+  yum:
+    name: "{{ item }}"
+    state: latest
+  loop:
+    - selinux-policy
+    - systemd
+  register: systemd_updated
+
+- name: Restart systemd
+  systemd:
+    daemon_reload: yes
+  when: systemd_updated|changed

playbooks/roles/exim/tasks/RedHat.yaml

@@ -3,3 +3,8 @@
     name: postfix
     enabled: false
     state: stopped
+
+- name: Install exim
+  yum:
+    name: "{{ package }}"
+    enablerepo: epel

playbooks/roles/exim/tasks/default.yaml

@@ -0,0 +1,4 @@
+- name: Install Exim
+  package:
+    state: present
+    name: '{{ package }}'

playbooks/roles/exim/tasks/main.yaml

@@ -14,11 +14,6 @@
       skip: true
   loop: "{{ query('first_found', params) }}"
 
-- name: Install Exim
-  package:
-    state: present
-    name: '{{ package }}'
-
 - name: Write Exim defaults file
   template:
     src: "{{ sysdefault_template }}"

playbooks/roles/exim/templates/aliases.j2

@@ -13,5 +13,7 @@ noc: root
 security: root
 
 {% for k, v in aliases|dictsort %}
+{% if v %}
 {{ k }}: {{ v }}
+{% endif %}
 {% endfor %}