I am struggling to derive container ID from within the container with cgroup v2 and containerd runtime on k8s. It looks it's not in "/sys/fs/cgroup/devices" "/proc/self/mountinfo" anymore.
In my example, the container ID is d34c51a7cfee43aa9680493fc85e4340a3b210a47a2ae0b4cdfac30b6d4e71ba.
I've tried to derive it from "/sys/fs/cgroup/devices" and "/proc/self/mountinfo" files but it's not there.
/ # more /sys/fs/cgroup/devices
more: /sys/fs/cgroup/devices: No such file or directory
/ #
/ # more /proc/self/mountinfo
1331 1214 0:444 / / rw,relatime master:357 - overlay overlay rw,lowerdir=/var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/16/fs,upperdir=/var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/17/fs,workdir=/var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/17/work
1332 1331 0:446 / /proc rw,nosuid,nodev,noexec,relatime - proc proc rw
1333 1331 0:447 / /dev rw,nosuid - tmpfs tmpfs rw,size=65536k,mode=755
1334 1333 0:448 / /dev/pts rw,nosuid,noexec,relatime - devpts devpts rw,gid=5,mode=620,ptmxmode=666
1335 1333 0:436 / /dev/mqueue rw,nosuid,nodev,noexec,relatime - mqueue mqueue rw
1336 1331 0:441 / /sys ro,nosuid,nodev,noexec,relatime - sysfs sysfs ro
1337 1336 0:29 / /sys/fs/cgroup ro,nosuid,nodev,noexec,relatime - cgroup2 cgroup rw
1338 1331 254:1 /docker/volumes/4120d1932295d7115866e8afa39d1b76da5dc3eb03fc741c318c048a76e0fd4b/_data/lib/kubelet/pods/bd07cd51-a990-4527-95e0-8f05cabb7cd1/etc-hosts /etc/hosts rw,relatime - ext4 /dev/vda1 rw
1339 1333 254:1 /docker/volumes/4120d1932295d7115866e8afa39d1b76da5dc3eb03fc741c318c048a76e0fd4b/_data/lib/kubelet/pods/bd07cd51-a990-4527-95e0-8f05cabb7cd1/containers/busybox/7a6416de /dev/termination-log rw,relatime - ext4 /dev/vda1 rw
1340 1331 254:1 /docker/volumes/4120d1932295d7115866e8afa39d1b76da5dc3eb03fc741c318c048a76e0fd4b/_data/lib/containerd/io.containerd.grpc.v1.cri/sandboxes/1a45ea3e4e28881f0ae632349b18f08cc46a22f4b73ab03d3a387961512f92b3/hostname /etc/hostname rw,relatime - ext4 /dev/vda1 rw
1341 1331 254:1 /docker/volumes/4120d1932295d7115866e8afa39d1b76da5dc3eb03fc741c318c048a76e0fd4b/_data/lib/containerd/io.containerd.grpc.v1.cri/sandboxes/1a45ea3e4e28881f0ae632349b18f08cc46a22f4b73ab03d3a387961512f92b3/resolv.conf /etc/resolv.conf rw,relatime - ext4 /dev/vda1 rw
1342 1333 0:433 / /dev/shm rw,nosuid,nodev,noexec,relatime - tmpfs shm rw,size=65536k
1343 1331 0:432 / /var/run/secrets/kubernetes.io/serviceaccount ro,relatime - tmpfs tmpfs rw,size=16393920k
1215 1332 0:446 /bus /proc/bus ro,nosuid,nodev,noexec,relatime - proc proc rw
1216 1332 0:446 /fs /proc/fs ro,nosuid,nodev,noexec,relatime - proc proc rw
1217 1332 0:446 /irq /proc/irq ro,nosuid,nodev,noexec,relatime - proc proc rw
1218 1332 0:446 /sys /proc/sys ro,nosuid,nodev,noexec,relatime - proc proc rw
1219 1332 0:446 /sysrq-trigger /proc/sysrq-trigger ro,nosuid,nodev,noexec,relatime - proc proc rw
1220 1332 0:449 / /proc/acpi ro,relatime - tmpfs tmpfs ro
1221 1332 0:447 /null /proc/kcore rw,nosuid - tmpfs tmpfs rw,size=65536k,mode=755
1222 1332 0:447 /null /proc/keys rw,nosuid - tmpfs tmpfs rw,size=65536k,mode=755
1223 1332 0:447 /null /proc/timer_list rw,nosuid - tmpfs tmpfs rw,size=65536k,mode=755
1224 1336 0:450 / /sys/firmware ro,relatime - tmpfs tmpfs ro
Similar topic: How to get docker container ID from within the container with cgroup v2
