pub const KTSTR_CGROUP_WALK_ROOT_ENV: &str = "KTSTR_CGROUP_WALK_ROOT";Expand description
Name of the environment variable that overrides the cgroup-fs
root crate::cgroup::CgroupManager::setup walks down from when
enabling controllers in every ancestor’s cgroup.subtree_control.
Empty / unset falls back to /sys/fs/cgroup (the canonical
cgroup-v2 mount). Non-empty value must be a prefix of
KTSTR_HOST_CGROUP_PARENT_ENV’s configured parent so the walk
stays inside the directory the operator owns; values that do not
satisfy the prefix invariant are rejected upfront by
crate::cgroup::CgroupManager::with_walk_root.
Exists for cgroup-v2 user delegation (Mode B/C: systemd
Delegate=yes, container nsdelegate): the operator owns
subtree_control writes only inside the delegated subtree, and a
blind walk from /sys/fs/cgroup down would EACCES at the
user.slice / container-root boundary. Setting the walk root to
the delegation boundary makes the setup-time controller-enable
walk stop there.
§Empty-string contract
Empty string is observationally identical to unset: both fall
back to /sys/fs/cgroup (the crate::cgroup::CgroupManager::new
default). This mirrors the sibling env vars; a shell that exports
KTSTR_CGROUP_WALK_ROOT= (without a value) explicitly opts back
into the default rather than passing an empty path down to
crate::cgroup::CgroupManager::with_walk_root (which would
always fail the prefix invariant).
Single source of truth so the name is not spelled by hand at each
reader. Mirrors the sibling KTSTR_HOST_CGROUP_PARENT_ENV
constant-defined naming convention; a single grep across
KTSTR_*_ENV consts gives the operator the complete env-var
inventory.
Read by crate::test_support::dispatch::resolve_host_cgroup_parent.