d4science-ghn-cluster/cassandra.yml: Add roles to install ganglia and nagios. Enable iptables.

d4science-ghn-cluster/group_vars/cassandra_dev/iptables.yml, d4science-ghn-cluster/group_vars/cassandra_prod/iptables.yml: iptables rules.
library/roles/cassandra/defaults/main.yml: Enable cassandra at boot time by default.

cassandra/defaults/main.yml

@@ -2,8 +2,13 @@
 cassandra_install_from_external_repo: True
 cassandra_install_packages: True
 cassandra_latest_version: True
-cassandra_start_server: 'no'
+cassandra_start_server: True
 cassandra_cluster_enabled: False
+cassandra_cluster_port: 7000
+cassandra_cluster_ssl_port: 7001
+cassandra_native_transport_port: 9042
+cassandra_rpc_port: 9160
+cassandra_jmx_port: 7199
 cassandra_allowed_hosts:
   - 127.0.0.1/8
   - '{{ ansible_default_ipv4.address }}/32'

cassandra/handlers/main.yml

@@ -1,7 +1,5 @@
 ---
-- name: Update apt cache
-  apt: update_cache=yes
-  ignore_errors: true
-
 - name: Restart cassandra
   service: name=cassandra state=restarted
+  when: cassandra_start_server
+

cassandra/tasks/main.yml

@@ -5,15 +5,8 @@
   tags: cassandra
 
 - name: Install the cassandra repository
-  copy: content="deb http://debian.datastax.com/community stable main" dest=/etc/apt/sources.list.d/cassandra.sources.list owner=root group=root mode=044
+  copy: content="deb http://debian.datastax.com/community stable main" dest=/etc/apt/sources.list.d/cassandra.sources.list owner=root group=root mode=0444 update_cache=yes
   when: cassandra_install_from_external_repo
-  register: external_repo
-  tags: cassandra
-
-- name: Update the apt cache
-  apt: update_cache=yes
-  when: ( external_repo | changed )
-  ignore_errors: True
   tags: cassandra
 
 - name: Install a specific version of cassandra server
@@ -58,13 +51,13 @@
     - cassandra_latest_version
   tags: cassandra
 
-- name: Ensure cassandra is started
+- name: Ensure cassandra is started and enabled
   service: name=cassandra state=started enabled=yes
-  when: ( cassandra_start_server is defined ) and ( cassandra_start_server == 'yes' )
+  when: cassandra_start_server
   tags: cassandra
 
 - name: Ensure cassandra is stopped and disabled
   service: name=cassandra state=stopped enabled=no
-  when: ( cassandra_start_server is defined ) and ( cassandra_start_server == 'no' )
+  when: not cassandra_start_server
   tags: cassandra