Fixes an issue with --wipe-disks

The awk expression that was in use prior to this change was fragile
and in some cases could incorrectly identify the unmounted block
devices. This change switches to parsing the json output which
should hopefully be more robust.

Change-Id: Ifa89e7307eb445b4f1708f0c6ac3409b3f96aafe
Story: 2010367
Task: 46578

ansible/roles/wipe-disks/library/blockdevice_info.py

@@ -0,0 +1,74 @@
+#!/usr/bin/python3
+
+DOCUMENTATION = '''
+---
+module: blockdevice_info
+short_description: Returns information about block devices
+version_added: "N/A"
+description:
+    - "Returns information about block devices"
+author:
+    - Will Szumski
+'''
+
+EXAMPLES = '''
+- name: Retrieve information about block devices
+  blockdevice_info:
+  become: true
+  register: result
+'''
+
+RETURN = '''
+umounted:
+    description: A list of all umounted block devices.
+    type: list
+    returned: always
+'''
+
+import json
+
+from ansible.module_utils.basic import AnsibleModule
+
+def _has_mounts(device):
+    if device["mountpoint"]:
+        return True
+    for child in device.get("children", []):
+        if _has_mounts(child):
+            return True
+    return False
+
+def unmounted(module, lsblk):
+    result = []
+    for device in lsblk.get("blockdevices", []):
+        if not _has_mounts(device) and device["type"] == 'disk':
+            result.append(device["name"])
+    return result
+
+def run_module():
+    # The module takes no argumnets.
+    module_args = dict()
+
+    result = dict(
+        changed=False,
+        unmounted=[]
+    )
+
+    module = AnsibleModule(
+        argument_spec=module_args,
+        supports_check_mode=True
+    )
+
+    _rc, stdout, _stderr = module.run_command("lsblk -J")
+    lsblk = json.loads(stdout)
+
+    result['unmounted'] = unmounted(module, lsblk)
+
+    module.exit_json(**result)
+
+
+def main():
+    run_module()
+
+
+if __name__ == '__main__':
+    main()

ansible/roles/wipe-disks/tasks/main.yml

@@ -14,13 +14,9 @@
     update_cache: "{{ True if ansible_facts.os_family == 'Debian' else omit }}"
   become: True
 
-- name: Check for unmounted block devices
-  shell: >
-    lsblk -i -o NAME,MOUNTPOINT   | awk \
-        '/^ *[|`]-/ && NF > 1       { mounts[master_dev] = mounts[master_dev] $2 " " }
-         /^(nvme|sd|vd)/ && NF == 1 { master_dev = $1; mounts[master_dev] = "" }
-         END                        { for (dev in mounts) if (mounts[dev] == "") print dev }'
-  register: unmounted_devices
+- name: Gather blockdevice facts
+  blockdevice_info:
+  register: block_devices
   changed_when: False
 
 - name: Ensure that all unmounted block devices have LVM state removed
@@ -45,12 +41,12 @@
         fi
         pvremove -yff /dev/{{ item }}
     fi
-  with_items: "{{ unmounted_devices.stdout_lines }}"
+  with_items: "{{ block_devices.unmounted }}"
   become: True
 
 - name: Ensure that all unmounted block devices have filesystems wiped
   command: "wipefs -f /dev/{{ item }}"
-  with_items: "{{ unmounted_devices.stdout_lines }}"
+  with_items: "{{ block_devices.unmounted }}"
   become: True
   # The command can fail in some cases which are valid, so ignore the
   # result.
@@ -58,5 +54,5 @@
 
 - name: Ensure that all unmounted block device headers are zeroed
   command: "dd if=/dev/zero of=/dev/{{ item }} bs=1M count=100"
-  with_items: "{{ unmounted_devices.stdout_lines }}"
+  with_items: "{{ block_devices.unmounted }}"
   become: True

releasenotes/notes/fix-issue-with-wipefs-destroying-mounted-filesystems-77cdfda91689d7d1.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixes an issue where a host configure with ``--wipe-disks`` would
+    wipe block devices that were mounted. See `story
+    2010367 <https://storyboard.openstack.org/#!/story/2010367>`__ for details.