Validation to verify undercloud disk size reqs

Change-Id: If717f388d9c761bc40d95d899c01a526e1b2d828

validations/undercloud-disk-space.yaml

@@ -0,0 +1,35 @@
+---
+- hosts: undercloud
+  vars:
+    metadata:
+      name: Verify undercloud fits the disk space requirements
+      description: >
+        Make sure that the root partition on the undercloud node is large enough.
+
+        We first check for an explicit `/var` mount point since that's
+        where we store logs and images and if it doesn't exist, we
+        fall back to `/`.
+
+        http://tripleo.org/environments/environments.html#id5
+      groups:
+        - prep
+        - pre-introspection
+    min_undercloud_disk_gb: 60
+  tasks:
+  - name: Verify disk space in /var (if it exists)
+    # NOTE(shadower): 1073741824 == (1024 * 1024 * 1024), i.e. bytes
+    # in a gigabyte
+    fail: msg="The available space on the /var partition is {{ item.size_available|int / 1073741824 }} GB, but it should be at least {{ min_undercloud_disk_gb }} GB."
+    with_items: "{{ ansible_mounts }}"
+    when: "'/var' == '{{ item.mount }}'"
+    failed_when: "{{ min_undercloud_disk_gb|int * 1073741824 }} >= {{ item.size_available|int }}"
+    # Notify the next task that we've checked /var (and that it exists)
+    changed_when: True
+    register: previous
+
+  - name: Verify root disk space
+    fail: msg="The available space on the root partition is {{ item.size_available|int / 1073741824 }} GB, but it should be at least {{ min_undercloud_disk_gb }} GB."
+    with_items: "{{ ansible_mounts }}"
+    # Only run this when /var doesn't exist
+    when: "{{ not previous.changed }} and '/' == '{{ item.mount }}'"
+    failed_when: "{{ min_undercloud_disk_gb|int * 1073741824 }} >= {{ item.size_available|int }}"