we love systemd and are making our apps dependent on it.
- Default OS of our customers is RHEL 6.
- systemd depends on /sys/fs/cgroup interface but its not present there:
# ls /sys/fs/
# cat /proc/cgroups
#subsys_name hierarchy num_cgroups enabled
cpuset 1 6 1
ns 0 1 1
cpu 2 6 1
cpuacct 3 6 1
memory 4 6 1
devices 5 6 1
freezer 6 6 1
net_cls 7 2 1
blkio 8 6 1
perf_event 0 1 1
net_prio 0 1 1
# ls /cgroup
blkio cpu cpuacct cpuset devices freezer memory net_cls
# uname -r
One can't mount it into the countainer at the expected place, since /sys/fs/ is not writeable to create a mountpoint.
Output e.g. for docker (but lxc has same problem):
# docker run -ti --privileged -e "container=docker" debian:jessie /sbin/init
-> Failed to mount tmpfs at /sys/fs/cgroup: No such file or directory
=> Any possibility to have systemd be not dependent on /sys/fs/cgroup but only on /proc and/or /cgroup ?
Nope. systemd requires a lot of kernel features that are not available in the RHEL 6 kernel. It's really not just about /cgroup vs. /sys/fs/cgroup...
Sorry, but this cannot work.
Ok - danke dir. First reliable info regarding this :-)
We'll have to push our customers to upgrade their kernels to > 3.8 then, saw those available on EPEL.