chore: config improvements (#32)

Author: markovejnovic

config/config.exs

@@ -12,24 +12,20 @@ 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,
       config: [hosts: [:"a@127.0.0.1", :"b@127.0.0.1", :"c@127.0.0.1"]]
     ]
   ]
 
-config :hyper,
-  cgroup_parent: "hyper",
-  uid_gid_range: {900_000, 999_999},
-  layer_dir: "/srv/hyper/layers"
-
 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

@@ -2,29 +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).
+# 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
+# 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
-  endpoint = System.get_env("OTEL_EXPORTER_OTLP_ENDPOINT", "https://api.honeycomb.io")
+  hyper_config = System.get_env("HYPER_CONFIG") || "/etc/hyper/config.exs"
 
-  headers =
-    case System.get_env("HONEYCOMB_API_KEY") do
-      nil -> []
-      "" -> []
-      key -> [{"x-honeycomb-team", key}]
-    end
+  operator =
+    if File.exists?(hyper_config),
+      do: Config.Reader.read!(hyper_config, env: config_env()),
+      else: []
 
-  config :opentelemetry_exporter,
-    otlp_protocol: :http_protobuf,
-    otlp_endpoint: endpoint,
-    otlp_headers: headers
+  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