Hi,
On Thu, Jun 22, 2023 at 7:52 PM Spike White spikewhitetx@gmail.com 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 sssIt 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 atikhono@redhat.com wrote:
Hi,
On Thu, Jun 22, 2023 at 4:47 PM Spike White spikewhitetx@gmail.com 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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