Added ability for mongo role to do simple replica set clusters

By default this should keep the role the same.  The only catch with this implementation
is that the ansible mongodb_user module doesn't handle slaves particularly well. So if you
have a cluster than any task that creates a user will succeed on the master and fail on all
slaves.

playbooks/roles/mongo/defaults/main.yml

@@ -4,6 +4,9 @@ mongo_logappend: true
 mongo_version: 2.4.7
 mongo_bind_ip: 127.0.0.1
 mongo_extra_conf: ''
+mongo_key_file: '/etc/mongodb_key'
+mongo_repl_set: rs0
+mongo_cluster_members: 
 
 MONGO_USERS:
   - user: cs_comments_service

playbooks/roles/mongo/tasks/main.yml

@@ -38,6 +38,15 @@
   file: src={{ storage_base_dir }}/mongodb dest=/var/lib/mongodb state=link
   tags: mongo
 
+- name: mongo | copy mongodb key file
+  copy: >
+    src={{ secure_dir }}/files/mongo_key
+    dest={{ mongo_key_file }}
+    mode=0600
+    owner=mongodb
+    group=mongodb
+  when: mongo_clustered is defined
+
 - name: mongo | copy configuration template
   template: src=mongodb.conf.j2 dest=/etc/mongodb.conf backup=yes
   notify: restart mongo
@@ -51,6 +60,18 @@
   wait_for: port=27017 delay=2
   tags: mongo
 
+- name: mongo | Create the file to initialize the mongod replica set
+  template: src=repset_init.j2 dest=/tmp/repset_init.js
+  when: mongo_clustered is defined
+  tags: mongo
+
+- name: mongo | Initialize the replication set
+  shell: /usr/bin/mongo  /tmp/repset_init.js 
+  when: mongo_clustered is defined
+  tags: mongo
+
+# Ignoring errors here because slave instances will fail this command
+# since slaveOk is false in ansible 1.3.
 - name: mongo | create a mongodb user
   mongodb_user: >
     database={{ item.database }}
@@ -59,3 +80,4 @@
     state=present
   with_items: MONGO_USERS
   tags: mongo
+  ignore_errors: yes

playbooks/roles/mongo/templates/mongodb.conf.j2

@@ -15,6 +15,11 @@ bind_ip = {{ mongo_bind_ip }}
 # Enable journaling, http://www.mongodb.org/display/DOCS/Journaling
 journal=true
 
+{% if mongo_clustered is defined %}
+keyFile = {{ mongo_key_file }}
+replSet = {{ mongo_repl_set }}
+{% endif %}
+
 # Enables periodic logging of CPU utilization and I/O wait
 #cpu = true
 
@@ -93,4 +98,4 @@ journal=true
 # Size limit for in-memory storage of op ids.
 #opIdMem = <bytes>
 
-{{ mongo_extra_conf }}
\ No newline at end of file
+{{ mongo_extra_conf }}

playbooks/roles/mongo/templates/repset_init.j2

+config = {_id: '{{ mongo_repl_set }}', members: [
+	   {% for host in mongo_cluster_members %}
+	   {_id: {{ loop.index }}, host: '{{ host }}'}{% if not loop.last %},{% endif %}
+	   {% endfor %}
+           ]};
+rs.initiate(config)
+
+sleep(30000)
+rs.slaveOk()
+printjson(rs.status())