NAME¶

sss_cache - perform cache cleanup

SYNOPSIS¶

sss_cache [options]

DESCRIPTION¶

sss_cache invalidates records in SSSD cache. Invalidated records are forced to be reloaded from server as soon as related SSSD backend is online. Options that invalidate a single object only accept a single provided argument.

OPTIONS¶

-E,--everything

-u,--user login

-U,--users

-g,--group group

-G,--groups

-n,--netgroup netgroup

-N,--netgroups

-s,--service service

-S,--services

-a,--autofs-map autofs-map

-A,--autofs-maps

-h,--ssh-host hostname

-H,--ssh-hosts

-r,--sudo-rule rule

-R,--sudo-rules

-d,--domain domain

-?,--help

EFFECTS ON THE FAST MEMORY CACHE¶

sss_cache also invalidates the memory cache. Since the memory cache is a file which is mapped into the memory of each process which called SSSD to resolve users or groups the file cannot be truncated. A special flag is set in the header of the file to indicate that the content is invalid and then the file is unlinked by SSSD's NSS responder and a new cache file is created. Whenever a process is now doing a new lookup for a user or a group it will see the flag, close the old memory cache file and map the new one into its memory. When all processes which had opened the old memory cache file have closed it while looking up a user or a group the kernel can release the occupied disk space and the old memory cache file is finally removed completely.

A special case is long running processes which are doing user or group lookups only at startup, e.g. to determine the name of the user the process is running as. For those lookups the memory cache file is mapped into the memory of the process. But since there will be no further lookups this process would never detect if the memory cache file was invalidated and hence it will be kept in memory and will occupy disk space until the process stops. As a result calling sss_cache might increase the disk usage because old memory cache files cannot be removed from the disk because they are still mapped by long running processes.

A possible work-around for long running processes which are looking up users and groups only at startup or very rarely is to run them with the environment variable SSS_NSS_USE_MEMCACHE set to "NO" so that they won't use the memory cache at all and not map the memory cache file into the memory. In general a better solution is to tune the cache timeout parameters so that they meet the local expectations and calling sss_cache is not needed.

SEE ALSO¶

sssd(8), sssd.conf(5), sssd-ldap(5), sssd-ldap-attributes(5), sssd-krb5(5), sssd-simple(5), sssd-ipa(5), sssd-ad(5), sssd-files(5), sssd-sudo(5), sssd-session-recording(5), sss_cache(8), sss_debuglevel(8), sss_obfuscate(8), sss_seed(8), sssd_krb5_locator_plugin(8), sss_ssh_authorizedkeys(8), sss_ssh_knownhostsproxy(8), sssd-ifp(5), pam_sss(8). sss_rpcidmapd(5) sssd-systemtap(5)

AUTHORS¶

The SSSD upstream - https://github.com/SSSD/sssd/