Instruction file imported from rk8s-dev/rk8s (.github/instructions/rkl.instructions.md). Copyright stays with the author.

RKL (Runtime) – Path-specific Copilot Instructions

Scope

RKL implements the container and pod runtime:

• Pod lifecycle (create, start, stop, cleanup)
• Namespace, cgroup, and filesystem setup
• OCI/CRI interoperability

Goals: fast startup, low overhead, robust observability, suitable for both edge and developer machines.

Coding & design

• Separate responsibilities: image fetch, rootfs setup, namespace/mount, cgroup, exec/attach.
• Use non-blocking async I/O (Tokio); long-running tasks must support cancellation and timeouts.
• Emit tracing spans for all lifecycle events (container_id, pod_uid, phase, duration).
• Failures must be rollback-safe: cleanup mounts, networks, temp dirs.
• For OCI integration: reuse existing runtime components (e.g., youki, crun) when feasible, clearly define supported features.

Tests & benchmarks

• Integration tests: minimal container and pod lifecycle.
• Stress tests: concurrent creation of N pods.
• Benchmarks: startup latency, resident memory, scalability; use criterion.

Copilot guidance

• Generate Rust runtime code first, then optional CLI sample (rkl container run …).
• Focus templates on process management, cgroup v2, mount orchestration, signal handling, cleanup hooks.