Add basic support for managing logical volumes (LVM)

Add a 'volumemgr' role that manages logical volumes on servers by
looking at the 'volumes' attribute of our services.

It can create LVs, format them with ext4, and mount them with the
right permissions.

roles/volumemgr/tasks/main.yml

+---
+
+- include_tasks: service.yml
+  with_items: "{{ float_enabled_services }}"
+  loop_control:
+    loop_var: service_name_iter
+  when: "enable_volumes | default(False)"

roles/volumemgr/tasks/service.yml

+---
+
+- set_fact:
+    service: "{{ services[service_name_iter] }}"
+
+- include_tasks: volume.yml
+  with_items: "{{ service.volumes | default([]) }}"
+  loop_control:
+    loop_var: volume

roles/volumemgr/tasks/volume.yml

+---
+
+- set_fact:
+    lv_name: "{{ service.name }}-{{ volume.name }}"
+
+- set_fact:
+    lv_dev: "/dev/{{ volumes_vg | default('vg0') }}/{{ lv_name }}"
+
+- name: "Create mount point for volume {{ lv_name }}"
+  file:
+    path: "{{ volume.path }}"
+    owner: "{{ volume.owner | default('root') }}"
+    group: "{{ volume.group | default('root') }}"
+    mode: "{{ volume.mode | default('0755') }}"
+    state: directory
+
+- name: "Create the LV {{ lv_name }}"
+  lvol:
+    vg: "{{ volumes_vg | default('vg0') }}"
+    lv: "{{ lv_name }}"
+    size: "{{ volume.size | default('10g') }}"
+
+- name: "Create a filesystem on {{ lv_name }}"
+  filesystem:
+    dev: "{{ lv_dev }}"
+    fstype: ext4
+  register: lv_mkfs
+
+- name: "Add the /etc/fstab entry for {{ lv_name }}"
+  mount:
+    path: "{{ volume.path }}"
+    src: "{{ lv_dev }}"
+    fstype: ext4
+    state: mounted
+
+# Set permissions again if we have created the filesystem.
+- name: "Fix permissions for {{ volume.path }}"
+  file:
+    path: "{{ volume.path }}"
+    owner: "{{ volume.owner | default('root') }}"
+    group: "{{ volume.group | default('root') }}"
+    mode: "{{ volume.mode | default('0755') }}"
+    state: directory
+  when: lv_mkfs.changed

services.yml.default

@@ -15,6 +15,13 @@ frontend:
     - replds@acme.service
   ports:
     - 5005
+  volumes:
+    - name: cache
+      path: /var/cache/nginx
+      owner: nginx
+      group: nginx
+      mode: "0700"
+      size: 20g
 
 log-collector:
   scheduling_group: backend
@@ -58,6 +65,13 @@ log-collector:
   ports:
     - 6514
     - 9200
+  volumes:
+    - name: elasticsearch
+      path: /var/lib/elasticsearch
+      size: 100g
+      owner: docker-log-collector
+      group: docker-log-collector
+      mode: "0700"
 
 prometheus:
   scheduling_group: backend
@@ -104,6 +118,11 @@ prometheus:
     - prometheus-blackbox-exporter.service
   ports:
     - 9094
+  volumes:
+    - name: metrics
+      path: /var/lib/prometheus
+      owner: prometheus
+      group: prometheus
 
 sso-server:
   num_instances: 1