Basically, if you use systemd as the init system, then yes - it is the only API [1] . If you dont want to use systemd then there are alternate implementations of the cgroup API (e.g. cgmanager - http://cgmanager.linuxcontainers.org/ ). IMHO, they are both incompatible with each other.
Lennart has a reasonable justification of why systemd is implementing it's own API [2]
Basically, if you use systemd as the init system, then yes - it is the only API [1] . If you dont want to use systemd then there are alternate implementations of the cgroup API (e.g. cgmanager - http://cgmanager.linuxcontainers.org/ ). IMHO, they are both incompatible with each other.
Lennart has a reasonable justification of why systemd is implementing it's own API [2]
[1] https://lwn.net/Articles/557111/ [2] https://lwn.net/Articles/557140/