Use aws-lc-rs feature in rusttls

.claude/CHANGELOG.md

@@ -9,6 +9,36 @@ The format is based on the regulated environment requirements:
 
 ---
 
+## [2026-06-26 10:00] - Switch rustls crypto provider ring -> aws-lc-rs (fixes mTLS to k0smotron-hosted control planes)
+
+**Author:** Erick Bourgeois
+
+### Changed
+- `Cargo.toml`: `kube` now uses `default-features = false` + `["…, "rustls-tls", "aws-lc-rs"]`
+  instead of the default that pulls the `ring` crypto provider. `ring` leaves the lock; the
+  rustls TLS stack now runs on aws-lc-rs (BoringSSL-derived). 682 lib tests pass, fmt/clippy clean.
+
+### Why
+5-Spot's child client could not complete the mTLS TLS-1.3 handshake against a k0smotron-hosted
+control plane — it stalled after the client-certificate step and timed out
+(`client error (Connect) -> deadline has elapsed`), so node taints/drains never happened on the
+hosted-CP tier. Proven on a live cluster that `curl --cert/--key` (OpenSSL) and `client-go`
+(kubelet/kubectl) complete the *identical* handshake to the *same* endpoint in ~13ms, while
+kube-rs/rustls-with-`ring` hangs (captured via `rustls=trace`). aws-lc-rs shares OpenSSL/BoringSSL's
+crypto lineage, so it behaves like the clients that work.
+
+### Build note
+CI builds **natively per arch** (`ubuntu-24.04` + `ubuntu-24.04-arm`, plain `cargo build --release`),
+so aws-lc-rs compiles natively (cmake + cc, present on GitHub runners) — no cross-toolchain and no
+OpenSSL runtime lib in the distroless image, i.e. it avoids the cross-compile problem that motivated
+`ring` in the first place.
+
+### Impact
+- [ ] Breaking change
+- [x] Requires cluster rollout
+- [ ] Config change only
+- [ ] Documentation only
+
 ## [2026-06-24 11:30] - Name the HTTP status codes used in API-error matching (no magic 404/409/429)
 
 **Author:** Erick Bourgeois

Cargo.toml

@@ -45,7 +45,13 @@ path = "src/bin/spot_schedule_capital_markets.rs"
 # Controller. The feature is "unstable" in the SemVer sense (the API
 # may change between minor kube-runtime versions) but is the canonical
 # way to push external triggers into the controller loop.
-kube = { version = "3.1", features = ["runtime", "derive", "client", "ws", "unstable-runtime"] }
+# TLS: use rustls with the aws-lc-rs crypto provider (BoringSSL-derived) instead of the
+# `ring` provider kube pulls by default. `ring` cannot complete the mTLS TLS-1.3 handshake
+# against a k0smotron-hosted control plane (it stalls after the client cert step), whereas
+# aws-lc-rs — same crypto lineage as OpenSSL/BoringSSL, which client-go and curl use
+# successfully against that exact endpoint — does. default-features=false drops the default
+# `ring`; we re-add `client` + `rustls-tls` explicitly alongside `aws-lc-rs`.
+kube = { version = "3.1", default-features = false, features = ["runtime", "derive", "client", "ws", "unstable-runtime", "rustls-tls", "aws-lc-rs"] }
 kube-lease-manager = "0.11"
 k8s-openapi = { version = "0.27", features = ["latest", "schemars"] }
 tokio = { version = "1", features = ["full"] }