On Thu, Aug 29, 2013 at 4:13 PM, Jan Kaluza <jkaluza@xxxxxxxxxx> wrote: > Add new SCM type called SCM_CGROUP to send "cgroup_path" in SCM. > This is useful for journald (systemd logging daemon) to get additional context > with each log line received using UNIX socket. > > Signed-off-by: Jan Kaluza <jkaluza@xxxxxxxxxx> In many cases it's generally more useful to explain *why* something is done, not *where* it is used. It makes it easier for people to match the described problem to their own use-cases, where it possibly occurs too. The problem this patch solves is very generic and not so much specific to logging or the journal. Maybe something like this: "Server-like processes in many cases need credentials and other metadata of the peer, to decide if the calling process is allowed to request a specific action, or the server just wants to log away this type of information for auditing tasks. The current practice to retrieve such process metadata is to look that information up in procfs with the $PID received over SCM_CREDENTIALS. This is sufficient for long-running tasks, but introduces a race which cannot be worked around for short-living processes; the calling process and all the information in /proc/$PID/ is gone before the receiver of the socket message can look it up. This introduces a new SCM type called SCM_CGROUP to allow the direct attaching of "cgroup_path" to SCM, which is significantly more efficient and will reliably avoid the race with the round-trip over procfs." Thanks, Kay _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
