BPFComposer: Towards deterministic and safe composition of eBPF Programs (and their Shared state)

Deploying eBPF at scale requires programs from independent teams to coexist safely 1 and share state efficiently, yet the kernel provides almost no primitives to support this. The result is silent functionality loss, network degradation, and fleet-wide outages often undetected during isolated testing. We present BPFComposer, which helps address this by interposing on the kernel at two levels: a managed program chainer layer enforcing deterministic execution order and return-value isolation, and a shared map registry providing versioned, provider-consumer coordination. Deployed across millions of hosts, BPFComposer has eliminated over 400GB of redundant map memory fleet-wide and prevented recurrence of the failure classes that motivated its design.