multipath.aug - unable to set "blacklist{ wwid .*}"

[martinhoyer]

The multipath lens is now accepting only asterisk, which works in older versions, but not with newer packages in Fedora for example. Snip from journalctl:
multipath[1205]: Jun 07 11:31:04 | Invalid regular expression "" in multipath.conf. Using "."

I propose a change in line 36, adding another OR, for ".*"
https://github.com/hercules-team/augeas/blob/master/lenses/multipath.aug#L36
from
let wwid = kv "wwid" (Rx.word|"*")
to
let wwid = kv "wwid" (Rx.word|"*"|".*")

[lutter]

Hi,

thanks for bringing this up. I just did a little checking with multipath 0.7.4 in Fedora 28, and it appears that wwid and devnode in the blacklist accept a ton more crazy stuff. At least, multipath -d -v3 didn't complain about this crazy /etc/multipath.conf:

blacklist_exceptions {
        property "(SCSI_IDENT_|ID_WWN)"
}

blacklist {
        devnode ".*"
        devnode "[a-z]+(0|1):-\+=?'*"
        wwid "([a-z]+|ab?c).*"
        wwid ":+-'"
}

So, should we just allow pretty much anything for wwid and devnode in the blacklist ? Do you know when the change to accept regexps there was introduced in multipath ?

[martinhoyer]

Hi,

Do you know when the change to accept regexps there was introduced in multipath ?

I believe it was always using regexp, there was just a change in the parser. More info:

• RH_bz#1508841
• Fedora patch

[lutter]

Thanks for the additional detail. I put a slightly broader change into PR #565. Let me know if that works for you or not and I'll merge it.

[martinhoyer]

Looks good in my colleague testing. I've also done some manual testing and can confirm it fixes this issue. Thank You very much!

What I found, is every time you want to blacklist a wwid using 'set', the existing one gets overwritten. This might not be a desired action if we're blacklisting one wwid at the time. Same behaviour with and without PR #565.
Not sure if this is a real issue, please let me know what you think about it, and if you want me to open a separate issue.

[lutter]

You can do either. Using the /etc/multipath.conf from tests/root in the augeas sources, you can update an existing one with doing this in augtool (before you do this, do print /files/etc/multipath.conf to see what the tree looks like):

  set /files/etc/multipath.conf/blacklist[2]/wwid newvalue

If there are already multiple wwid nodes, you can pick one out with something like this:

  set /files/etc/multipath.conf/blacklist[2]/wwid[. = 'oldvalue'] newvalue

If there is no wwid with oldvalue, it will just create a new one.

The simplest way to add a new one is

  set /files/etc/multipath.conf/blacklist[2]/wwid[last()+1] newvalue

That will always create a new wwid entry at the end of the blacklist section.

[martinhoyer]

Thank You very much!
Completely forgot about this, I'm actually using the last()+1 elswhere.