Merge origin/main into chore/get-a-vm-running

origin/main (#32) refactored Hyper.Config into Hyper.Cfg.* modules
(Cfg.Tools/Jails/Dirs/Budget/Otel/Toml/...) and deleted config.ex. This
branch had independent VM-boot work on the same files. Resolution:

- config.ex: accept main's deletion; rewrite all Hyper.Config.X callers to
  the Hyper.Cfg.{Tools,Jails,Dirs,Img}.Y equivalents (jailer, node, reclaim,
  dmsetup).
- suid_helper/{blockdev,dmsetup,losetup}, jailer: keep THIS branch's
  helper-routed architecture (no --bin; the merged Rust helper reads tool
  paths from config and owns the privileged jailer flags).
- node.ex: keep check_firecracker_bins + dropped FireVMM.Provider (branch),
  but load budget via Hyper.Cfg.Budget (main).
- fire_vmm/provider.ex: stays deleted (branch dropped Provider).
- umoci.ex, runtime.exs, config.md: take main (already carry these features,
  refactored; config.md is main's comprehensive restructure).
- jailer_test: stub via Hyper.Cfg.Toml.put_cache/reload.

Gate green: compile --warnings-as-errors, format, 250 tests, dialyzer 0.

Author: markovejnovic

config/config.exs

@@ -12,8 +12,9 @@ config :opentelemetry,
 #     iex --name a@127.0.0.1 --cookie hyper -S mix
 #     iex --name b@127.0.0.1 --cookie hyper -S mix
 #
-# Swap the strategy for prod (DNSPoll / EC2 tags).
-config :libcluster,
+# Swap the strategy for prod (DNSPoll / EC2 tags). Hyper forwards this straight
+# to libcluster; see `Hyper.Cfg.Cluster`.
+config :hyper, Hyper.Cfg.Cluster,
   topologies: [
     hyper: [
       strategy: Cluster.Strategy.Epmd,
@@ -24,7 +25,7 @@ config :libcluster,
 if config_env() == :test do
   config :opentelemetry, traces_exporter: :none
   # No cluster formation during tests.
-  config :libcluster, topologies: []
+  config :hyper, Hyper.Cfg.Cluster, topologies: []
 
   # JUnit XML for Codecov Test Analytics. A fixed report_dir (not the default
   # app_path) gives CI a stable path; automatic_create_dir? mkdirs it since

config/runtime.exs

@@ -2,54 +2,39 @@ import Config
 
 # Per-node resource budget. Lives in runtime config because it builds `Unit.*`
 # values, which are only loadable once the app's modules are on the code path.
-config :hyper, Hyper.Node.Config.Budget,
+config :hyper, Hyper.Cfg.Budget,
   mem_max: Unit.Information.gib(4),
   disk_max: Unit.Information.gib(4),
   cpu_max_load: 0.8,
+  cpu_max_cap: 4.0,
   disk_bw_cap: Unit.Bandwidth.gibps(1),
   disk_bw_max_load: 0.8,
   net_bw_cap: Unit.Bandwidth.gibps(1),
   net_bw_max_load: 0.8
 
-# Where to send traces. Defaults to Honeycomb; override OTEL_EXPORTER_OTLP_*
-# to point at any OTLP/HTTP backend (Collector, Grafana, etc).
-if config_env() != :test do
-  custom_endpoint = System.get_env("OTEL_EXPORTER_OTLP_ENDPOINT")
-  api_key = System.get_env("HONEYCOMB_API_KEY")
-
-  cond do
-    api_key not in [nil, ""] ->
-      config :opentelemetry_exporter,
-        otlp_protocol: :http_protobuf,
-        otlp_endpoint: custom_endpoint || "https://api.honeycomb.io",
-        otlp_headers: [{"x-honeycomb-team", api_key}]
-
-    custom_endpoint not in [nil, ""] ->
-      # A custom OTLP backend (e.g. a local Collector) needs no Honeycomb key.
-      config :opentelemetry_exporter,
-        otlp_protocol: :http_protobuf,
-        otlp_endpoint: custom_endpoint,
-        otlp_headers: []
-
-    true ->
-      # No backend configured: exporting to the Honeycomb default with no key
-      # 401s on every batch. Stay silent instead (typical for local dev). Set
-      # HONEYCOMB_API_KEY or OTEL_EXPORTER_OTLP_ENDPOINT to enable tracing.
-      config :opentelemetry, traces_exporter: :none
-  end
-end
-
 # Operator overrides from a well-known location. An optional Elixir config file
 # at /etc/hyper/config.exs (override the path with HYPER_CONFIG) is merged in
 # last, so its values win over every default set above. An absent file is a
-# no-op -- the normal case in dev and CI. Skipped under :test so the suite never
+# no-op — the normal case in dev and CI. Skipped under :test so the suite never
 # reads host state.
+#
+# OpenTelemetry exporter wiring is resolved through Hyper.Cfg.Otel so that the
+# operator's `config :hyper, Hyper.Cfg.Otel, ...` stanza (if present) takes
+# precedence over the TOML table and environment variables.
 if config_env() != :test do
   hyper_config = System.get_env("HYPER_CONFIG") || "/etc/hyper/config.exs"
 
-  if File.exists?(hyper_config) do
-    for {app, kw} <- Config.Reader.read!(hyper_config, env: config_env()) do
-      config app, kw
-    end
+  operator =
+    if File.exists?(hyper_config),
+      do: Config.Reader.read!(hyper_config, env: config_env()),
+      else: []
+
+  otel_exs = get_in(operator, [:hyper, Hyper.Cfg.Otel]) || []
+
+  case Hyper.Cfg.Otel.exporter_options(otel_exs) do
+    {:ok, opts} -> config :opentelemetry_exporter, opts
+    :none -> config :opentelemetry, traces_exporter: :none
   end
+
+  for {app, kw} <- operator, do: config(app, kw)
 end