Cfrtjryk

As all know the content of /tmp should be deleted after some time.

In my case we have machines ( redhat version 7.2 ) that are configured as following.

As we can see the service that is triggered to clean up /tmp will be activated every 24H ( 1d ).

systemd-tmpfiles-clean.timer from my machine:

more /lib/systemd/system/systemd-tmpfiles-clean.timer

#  This file is part of systemd.

#

#  systemd is free software; you can redistribute it and/or modify it

#  under the terms of the GNU Lesser General Public License as published by

#  the Free Software Foundation; either version 2.1 of the License, or

#  (at your option) any later version.



[Unit]

Description=Daily Cleanup of Temporary Directories

Documentation=man:tmpfiles.d(5) man:systemd-tmpfiles(8)



[Timer]

OnBootSec=15min

OnUnitActiveSec=1d

And this is the file that is responsible for the rules.
We can see that files/folders according to these rules will be deleted if they are older then 10 days, (this is my understanding , please correct me if I am wrong).

the rules are:

more /usr/lib/tmpfiles.d/tmp.conf

#  This file is part of systemd.

#

#  systemd is free software; you can redistribute it and/or modify it

#  under the terms of the GNU Lesser General Public License as published by

#  the Free Software Foundation; either version 2.1 of the License, or

#  (at your option) any later version.



# See tmpfiles.d(5) for details



# Clear tmp directories separately, to make them easier to override

v /tmp 1777 root root 10d

v /var/tmp 1777 root root 30d



# Exclude namespace mountpoints created with PrivateTmp=yes

x /tmp/systemd-private-%b-*

X /tmp/systemd-private-%b-*/tmp

x /var/tmp/systemd-private-%b-*

X /var/tmp/systemd-private-%b-*/tmp

But because we have a hadoop cluster, we noticed that /tmp contains thousands of empty folders and files, and also folders and files with content that are really huge.

Example:

drwx------    2 hive      hadoop      6 Dec 19 13:54 2d069b18-f07f-4c8b-a7c7-45cd8cfc9d42_resources

drwx------    2 hive      hadoop      6 Dec 19 13:59 ed46a2a0-f142-4bff-9a7b-f2d430aff26d_resources

drwx------    2 hive      hadoop      6 Dec 19 14:04 ce7dc2ca-7a12-4aca-a4ef-87803a33a353_resources

drwx------    2 hive      hadoop      6 Dec 19 14:09 43fd3ce0-01f0-423a-89e5-cfd9f82792e6_resources

drwx------    2 hive      hadoop      6 Dec 19 14:14 f808fe5b-2f27-403f-9704-5d53cba176d3_resources

drwx------    2 hive      hadoop      6 Dec 19 14:19 6ef04ca4-9ab1-43f3-979c-9ba5edb9ccee_resources

drwx------    2 hive      hadoop      6 Dec 19 14:24 387330de-c6f5-4055-9f43-f67d577bd0ed_resources

drwx------    2 hive      hadoop      6 Dec 19 14:29 9517d4d9-8964-41c1-abde-a85f226b38ea_resources

drwx------    2 hive      hadoop      6 Dec 19 14:34 a46a9083-f097-4460-916f-e431f5790bf8_resources

drwx------    2 hive      hadoop      6 Dec 19 14:39 81379a84-17c8-4b24-b69a-d91710868560_resources

drwx------    2 hive      hadoop      6 Dec 19 14:44 4b8ba746-12f5-4caf-b21e-52300b8712a5_resources

drwx------    2 hive      hadoop      6 Dec 19 14:49 b7a2f98b-ecf2-4e9c-a92f-0da31d12a81a_resources

drwx------    2 hive      hadoop      6 Dec 19 14:54 2a745ade-e1a7-421d-9829-c7eb915982ce_resources

drwx------    2 hive      hadoop      6 Dec 19 14:59 9dc1a021-9adf-448b-856d-b14e2cb9812b_resources

drwx------    2 hive      hadoop      6 Dec 19 15:04 5599580d-c664-4f2e-95d3-ebdf479a33b9_resources

drwx------    2 hive      hadoop      6 Dec 19 15:09 d97dfbb5-444a-4401-ba58-d338f1724e68_resources

drwx------    2 hive      hadoop      6 Dec 19 15:14 832cf420-f601-4549-b131-b08853339a39_resources

drwx------    2 hive      hadoop      6 Dec 19 15:19 cd1f10e2-ad4e-4b4e-a3cb-4926ccc5a9c5_resources

drwx------    2 hive      hadoop      6 Dec 19 15:24 19dff3c0-8024-4631-b8da-1d31fea7203f_resources

drwx------    2 hive      hadoop      6 Dec 19 15:29 23528426-b8fb-4d14-8ea9-2fb799fefe51_resources

drwx------    2 hive      hadoop      6 Dec 19 15:34 e3509760-9823-4e30-8d0b-77c5aee80efd_resources

drwx------    2 hive      hadoop      6 Dec 19 15:39 3c157b4d-917c-49ef-86da-b44e310ca30a_resources

drwx------    2 hive      hadoop      6 Dec 19 15:44 b370af30-5323-4ad5-b39e-f02a0dcdc6bb_resources

drwx------    2 hive      hadoop      6 Dec 19 15:49 18a5ea21-30f9-45a8-8774-6d8200ada7ff_resources

drwx------    2 hive      hadoop      6 Dec 19 15:54 ee776a04-f0e8-4295-9872-f8fc6482913e_resources

drwx------    2 hive      hadoop      6 Dec 19 15:59 f5935653-0bf6-4171-895a-558eef8b0773_resources

drwx------    2 hive      hadoop      6 Dec 19 16:04 e80ea30b-c729-48a2-897d-ae7c94a4fa04_resources

drwx------    2 hive      hadoop      6 Dec 19 16:09 fde6f7e4-89bd-41b4-99d3-17204bf66f05_resources

We are worried that /tmp will be full and services can't delete the content because of that.

So we want to delete the folders and files from /tmp according to this:

every folder/file will be deleted if it is older than 1 day

and service will be activated each 1 hour

So we intend to set the following:

OnUnitActiveSec=1h    ( in file /lib/systemd/system/systemd-tmpfiles-clean.timer )



v /tmp 1777 root root 1d (  in file /usr/lib/tmpfiles.d/tmp.conf )

Am I right here with the new settings?

secondly - after setting this, do we need to do something for it to take effect ?

This combination will certainly work. However, instead of removing all in /tmp every hour, you're probably better of by deleting the resource files and directories only, e.g.

R /tmp/*_resources

Keep in mind that your changes on the systemd and tmpfiles configuration should not be done in /usr or /lib. Instead, place the according overrides in /etc, e.g.

echo 'R /tmp/*_resources' >> /etc/tmpfiles.d/hadoop

cp /lib/systemd/system/systemd-tmpfiles-clean.timer 

   /etc/systemd/system/systemd-tmpfiles-clean.timer

$EDITOR /etc/systemd/system/systemd-tmpfiles-clean.timer

If you change the files in /usr or /lib you might end up with conflicts during upgrades.

If you already changed your files, make sure to reload the unit files with systemctl daemon-reload. Otherwise systemd won't pickup the change of your timer.