Merge pull request #2005 from edx/max/cassandra

Add cassandra role

playbooks/roles/cassandra/defaults/main.yml

+---
+cassandra_version: "2.0.14"
+
+# AFAIK there's no way to detect instance storage after the instaces has started.
+# Therefore, you MUST know the device names ahead of time.
+# If this is empty, no disks will be mounted and data will be put on the root volume.
+cassandra_ephemeral_disks: []
+#cassandra_ephemeral_disks: ["/dev/xvdb", "/dev/xvdc"]
+
+cassandra_data_dir_prefix: /var/lib/cassandra/data
+
+#should be parallel to cassandra_ephemeral_disks if there are any
+cassandra_data_dirs: ["data.1"]
+
+#These are set by the package. Don't change them!
+cassandra_user: "cassandra"
+cassandra_group: "cassandra"
+
+# cassandra.yaml basic configuration parameters
+cassandra_cluster_name: "Test Cluster"
+
+#Set this unless you want your node to only listen locally.
+cassandra_seeds: ["127.0.0.1"]
+
+#should eventually use EC2Snitch
+cassandra_snitch: "SimpleSnitch"
+
+#set this ONLY when initializing a new cluster with NO DATA
+cassandra_auto_bootstrap: false
+
+# For single-node locally-accessible deployments only! Otherwise, use:
+# cassandra_listen_address: ""
+cassandra_listen_address: localhost
\ No newline at end of file

playbooks/roles/cassandra/meta/main.yml

+---
+dependencies:
+  - common
+  - oraclejdk
\ No newline at end of file

playbooks/roles/cassandra/tasks/main.yml

+---
+#
+# edX Configuration
+#
+# github:     https://github.com/edx/configuration
+# wiki:       https://github.com/edx/configuration/wiki
+# code style: https://github.com/edx/configuration/wiki/Ansible-Coding-Conventions
+# license:    https://github.com/edx/configuration/blob/master/LICENSE.TXT
+#
+#
+#
+# Tasks for role cassandra
+#
+# Overview:
+#
+# This role sets up a cassandra node.
+
+- name: Unmount disks mounted to the wrong place
+  mount:
+    name: "{{ item[0].mount }}"
+    src: "{{ item[0].device }}"
+    fstype: "{{ item[0].fstype }}"
+    state: unmounted
+  when: item[1] == item[0].device and not item[0].mount.startswith(cassandra_data_dir_prefix)
+  with_nested:
+    - ansible_mounts
+    - cassandra_ephemeral_disks
+
+- name: Create data directories
+  file:
+    path: "{{ cassandra_data_dir_prefix }}/{{ item }}"
+    state: directory
+  with_items: cassandra_data_dirs
+
+- name: Mount ephemeral disks
+  mount:
+    name: "{{ cassandra_data_dir_prefix }}/{{ item.1 }}"
+    src: "{{ item.0 }}"
+    fstype: ext4
+    state: mounted
+  with_together: 
+    - cassandra_ephemeral_disks
+    - cassandra_data_dirs
+  when: cassandra_ephemeral_disks
+
+#Mounting a disk overlays its permissions
+- name: Set permissions on data dirs
+  file:
+    path: "{{ cassandra_data_dir_prefix }}/{{ item }}"
+    owner: "{{ cassandra_user }}"
+    group: "{{ cassandra_group }}"
+  with_items: cassandra_data_dirs
+
+- name: Add the datastax repository apt-key
+  apt_key:
+    url: "http://debian.datastax.com/debian/repo_key"
+    state: present
+
+- name: Add the datastax repository
+  apt_repository:
+    repo: "deb http://debian.datastax.com/community stable main"
+    state: present
+
+- name: Install the cassandra package
+  apt:
+    name: "cassandra={{ cassandra_version }}"
+    state: present
+    update_cache: yes
+
+- name: Update the cassandra configuration
+  template:
+    src: "{{item}}.j2"
+    dest: /etc/cassandra/{{item}}
+    owner: "{{cassandra_user}}"
+    group: "{{cassandra_group}}"
+    mode: 0644
+  with_items:
+    - "cassandra-env.sh"
+    - "cassandra.yaml"
+
+- name: restart cassandra
+  service:
+    name: cassandra
+    state: restarted