Hi,

On Thu, Jun 22, 2023 at 7:52 PM Spike White <[email protected]> wrote:

> Alexey,
>
> Thanks for the suggestion.
>
> This is a commercial application.  Cloudera's hadoop implementation.  No
> idea if they use getgrouplist() under the hood.  I can ask our Cloudera
> tech engineer, but I doubt he knows either.
>
> sssd-ad seems to work pretty well on these servers, except for these
> occasional hiccups.  It's over 150 nodes in this hadoop cluster, with only
> these occasional hiccups.  Been AD integrated for >1 yr and app team happy
> (except for one annoying occasional cross-domain caching issue.)
>
> In particular, sssd finds its AD site so it's binding to AD DCs local to
> this datacenter.  (I checked that first thing.)
>
> These sporadic hiccups I discuss earlier seem limited to local users only,
> looking up their group memberships.
>
> Would the /etc/nsswitch.conf file syntax be:
>
>      initgroups:  files [SUCCESS=return] systemd sss
>
> It seems this would apply for all accounts that were members of local
> groups and not just these specific accounts.  (Not sure that's a problem
> for this particular app team, but I've seen AD accounts added in /etc/group
> as members of local groups.)
>
> To me, "filter_users" in sssd.conf where I specify the specific accounts
> would be safer.
>

Then filtering sounds as a way to go.

If you are courageous you can also try to read SSSD logs to figure out the
reason for those "sporadic hiccups".
Latest version, around sssd-2.8+, should make it easier to track a specific
lookup across a set of logs.



>
> Spike
>
> On Thu, Jun 22, 2023 at 10:44 AM Alexey Tikhonov <[email protected]>
> wrote:
>
>> Hi,
>>
>> On Thu, Jun 22, 2023 at 4:47 PM Spike White <[email protected]>
>> wrote:
>>
>>> All,
>>>
>>> Successful sssd consumer here.
>>>
>>> Have an app team running Hadoop.  They're getting these performance
>>> errors in their app.
>>>
>>> This is from their app logs.
>>>
>>> ddlflhdm201.us.company.com
>>> WARN June 15, 2023 10:08 AM Groups Potential performance problem:
>>> getGroups(user=hbase) took 58022 milliseconds
>>>
>>
>> Does it use `getgrouplist()` under the hood?
>>
>>
>>> ddlflhdm304.us.company.com
>>> WARN June 15, 2023 8:38 AM Groups Potential performance problem:
>>> getGroups(user=mapred) took 39962 milliseconds
>>> ddlplhdm505.us.company.com
>>> WARN June 16, 2023 5:37 AM Groups Potential performance problem:
>>> getGroups(user=hdfs) took 62437 milliseconds.
>>> ddlplhdm305.us.company.com
>>> WARN June 15, 2023 9:36 PM Groups Potential performance problem:
>>> getGroups(user=hdfs) took 58017 milliseconds
>>>
>>> ddlplhdm505.us.company.com
>>> WARN June 10, 2023 8:01 AM Groups Potential performance problem:
>>> getGroups(user=yarn) took 58017 milliseconds.
>>>
>>>
>>> Interestingly, all these users are local users created by the Hadoop
>>> package installation.  (hbase, mapred, hdfs, yarn are all local users).
>>>
>>>
>>> These local users are members only of local groups.  So theoretically
>>> the search for group memberships should be lightning quick as the groups
>>> are found only in /etc/group.
>>>
>>>
>>> But since my /etc/nsswitch.conf looks like this:
>>>
>>>
>>> passwd:     files systemd sss
>>>
>>> group:      files systemd sss
>>>
>>> netgroup:   files sss
>>>
>>> automount:  files sss
>>>
>>> services:   files
>>>
>>> shadow:     files sss
>>>
>>> hosts:      files dns myhostname
>>>
>>
>> You might consider specifying 'initgroups' explicitly and using something
>> like '[SUCCESS=return]' between databases to avoid going to sss altogether
>> (but see below)
>>
>>>
>>>
>>> It not only searches local files for group membership, it searches AD as
>>> well.  And doesn't find it, as there is no such AD user or uid.
>>>  Eventually timing out.
>>>
>>>
>>> In /var/log/messages we see this around the same time frame as
>>>
>>>
>>> Jun 15 10:08:09 ddlflhdm201 sssd[be[amer.company.com]]: GSSAPI Error:
>>> An invalid name was supplied (Success)
>>>
>>
>> Is sssd-ad properly configured at this host?
>> Initgroups lookup for unknown users should be fast.
>>
>>
>>
>>>
>>> Is there a way to restrict these particular local app accounts from
>>> having their group memberships looked up in AD?
>>>
>>> I.e., my [nss] section looks like this today:
>>>
>>> [nss]
>>> #debug_level = 9
>>> filter_groups = root
>>> filter_users = root
>>> #override_homedir = /home/%u
>>>
>>> Can I do this?
>>>
>>> [nss]
>>> filter_users = root,  hbase, mapred, hdfs, yarn
>>>
>>> And would I want to set filter_users_in_groups = false?
>>>
>>> Spike White
>>>
>>>
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