parted: ansible detects a change only in dry-run

[huguesgr]

SUMMARY

Once the partition initially created, subsequent run give:

• "ok" without dry-run
• "changed" with dry-run (--check)
  The only difference there is between the two runs is the following line:

    "script": "unit KiB set 1 lvm on"

ISSUE TYPE

• Bug Report

COMPONENT NAME

parted

ANSIBLE VERSION

ansible 2.8.5
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/home/ansible/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/local/lib/python2.7/dist-packages/ansible-2.8.5-py2.7.egg/ansible
  executable location = /usr/local/bin/ansible
  python version = 2.7.12 (default, Oct  8 2019, 14:14:10) [GCC 5.4.0 20160609]

CONFIGURATION

OS / ENVIRONMENT

RHEL 7.4. Using SAN storage with multipath.

STEPS TO REPRODUCE

- name: create partition
  parted:
    device: '/dev/mapper/s_server01_backup_vg.1'
    number: 1
    state: present
    flags: [ lvm ]
    part_end: '100%'

EXPECTED RESULTS

Return "ok", which is what is returned without dry-run.
Here is the output without dry-run:

ok: [server01] => (item={u'device': u'/dev/mapper/s_server01_backup_vg.1', u'part_end': u'100%', u'number': 1}) => {
    "ansible_loop_var": "item", 
    "changed": false, 
    "disk": {
        "dev": "/dev/mapper/s_server01_backup_vg.1", 
        "logical_block": 512, 
        "model": "Linux device-mapper (multipath)", 
        "physical_block": 512, 
        "size": 209715200.0, 
        "table": "msdos", 
        "unit": "kib"
    }, 
    "invocation": {
        "module_args": {
            "align": "optimal", 
            "device": "/dev/mapper/s_server01_backup_vg.1", 
            "flags": [
                "lvm"
            ], 
            "label": "msdos", 
            "name": null, 
            "number": 1, 
            "part_end": "100%", 
            "part_start": "0%", 
            "part_type": "primary", 
            "state": "present", 
            "unit": "KiB"
        }
    }, 
    "item": {
        "device": "/dev/mapper/s_server01_backup_vg.1", 
        "number": 1, 
        "part_end": "100%"
    }, 
    "partitions": [
        {
            "begin": 16384.0, 
            "end": 209715200.0, 
            "flags": [
                "lvm"
            ], 
            "fstype": "", 
            "name": "", 
            "num": 1, 
            "size": 209698816.0, 
            "unit": "kib"
        }
    ], 
    "script": ""
}

ACTUAL RESULTS

Returns "changed" only in dry-run:

changed: [server01] => (item={u'device': u'/dev/mapper/s_server01_backup_vg.1', u'part_end': u'100%', u'number': 1}) => {
    "ansible_loop_var": "item", 
    "changed": true, 
    "disk": {
        "dev": "/dev/mapper/s_server01_backup_vg.1", 
        "logical_block": 512, 
        "model": "Linux device-mapper (multipath)", 
        "physical_block": 512, 
        "size": 209715200.0, 
        "table": "msdos", 
        "unit": "kib"
    }, 
    "invocation": {
        "module_args": {
            "align": "optimal", 
            "device": "/dev/mapper/s_server01_backup_vg.1", 
            "flags": [
                "lvm"
            ], 
            "label": "msdos", 
            "name": null, 
            "number": 1, 
            "part_end": "100%", 
            "part_start": "0%", 
            "part_type": "primary", 
            "state": "present", 
            "unit": "KiB"
        }
    }, 
    "item": {
        "device": "/dev/mapper/s_server01_backup_vg.1", 
        "number": 1, 
        "part_end": "100%"
    }, 
    "partitions": [
        {
            "begin": 16384.0, 
            "end": 209715200.0, 
            "flags": [
                "lvm"
            ], 
            "fstype": "", 
            "name": "", 
            "num": 1, 
            "size": 209698816.0, 
            "unit": "kib"
        }
    ], 
    "script": "unit KiB set 1 lvm on"
}

[ansibullbot]

cc @ColOfAbRiX
click here for bot help

[ansibullbot]

cc @MorrisA @bcoca @d-little @flynn1973 @gforster @kairoaraujo @marvin-sinister @mator @molekuul @ramooncamacho @wtcross
click here for bot help

[rosowiecki]

Dear @Wohlraj

Your ansible version is 2.8.5, branch 2.8 is currently accepting only critical bugfixes.

Could you repeat your test in current version (2.10 prerelase from devel branch)? From what I can read in current version parted module is more consistent and returns changed=True whenever parted command (except print) is run or would be run if check mode wasn't enabled, just like script/command modules do.

(Keep in mind: I'm not a project maintainer, just a contributor interested in parted module)

[rosowiecki]

Hint not related to your issue with ansible: you may use whole device for LVM physical volume without creating any partitions on it. I prefer this method, but I understand that it could be confusing because someone may not recognize that the device is already used, which may have terrible consequences.

[rosowiecki]

My previous comments were not so accurate, so I edited them. Parted module tries to detect if change in flags is needed, but it doesn't handle check mode well. I'll make a PR soon.