Custom cgroup-bpf programs in systemd (asg2019)

The primary focus is to gather feedback from systemd community regarding ongoing and future work to introduce custom cgroup-bpf programs to systemd. The motivation is to give a user a capability to attach their own cgroup-bpf programs to systemd containers. This is a continuation of <a href="https://github.com/systemd/systemd/issues/10227" title="discussion"> started at ASG2018 and followed by <a href="https://github.com/systemd/systemd/pull/12151" title="PR12151"> and <a href="https://github.com/systemd/systemd/pull/12419" title="PR12419">. Currently systemd utilizes BPF macro-assembly which is poorly extendable and maintainable, so the 1st iteration would be introducing `libbpf` library to systemd. The first attempt was made and it raised valid questions about `libbpf` testability and dependencies it introduces. We’d like to address that. Another topic of focus may be implementation details, such as how to store libbpf programs: either as bytecode or as restricted C which compiles with the rest of systemd. For attendees with no context a brief intro to eBPF will be made including new initiatives which may be of use to systemd, e.g. “Compile once, run everywhere”. Since this is ongoing work the agenda may vary depending on activity in PRs. about this event: https://cfp.all-systems-go.io/ASG2019/talk/M8DVWG/