Added an initial implementation of the config/spec

lib/beacon_api/controllers/v1/config_controller.ex

@@ -0,0 +1,57 @@
+defmodule BeaconApi.V1.ConfigController do
+  use BeaconApi, :controller
+  require Logger
+
+  alias BeaconApi.ApiSpec
+  alias BeaconApi.ErrorController
+  alias BeaconApi.Helpers
+  alias BeaconApi.Utils
+  alias LambdaEthereumConsensus.Store.BlockBySlot
+  alias LambdaEthereumConsensus.Store.Blocks
+  alias LambdaEthereumConsensus.Store.StoreDb
+
+  plug(OpenApiSpex.Plug.CastAndValidate, json_render_error_v2: true)
+
+  @chain_spec_removed_keys ["ATTESTATION_SUBNET_COUNT", "KZG_COMMITMENT_INCLUSION_PROOF_DEPTH", "UPDATE_TIMEOUT"]
+  @chain_spec_renamed_keys [{"MAXIMUM_GOSSIP_CLOCK_DISPARITY", "MAXIMUM_GOSSIP_CLOCK_DISPARITY_MILLIS"}]
+  @chain_spec_hex_fields [
+    "TERMINAL_BLOCK_HASH",
+    "GENESIS_FORK_VERSION",
+    "ALTAIR_FORK_VERSION",
+    "BELLATRIX_FORK_VERSION",
+    "CAPELLA_FORK_VERSION",
+    "DENEB_FORK_VERSION",
+    "ELECTRA_FORK_VERSION",
+    "DEPOSIT_CONTRACT_ADDRESS",
+    "MESSAGE_DOMAIN_INVALID_SNAPPY",
+    "MESSAGE_DOMAIN_VALID_SNAPPY",
+  ]
+
+  # NOTE: this function is required by OpenApiSpex, and should return the information
+  #  of each specific endpoint. We just return the specific entry from the parsed spec.
+  def open_api_operation(:get_spec),
+    do: ApiSpec.spec().paths["/eth/v1/config/spec"].get
+
+  @spec get_spec(Plug.Conn.t(), any) :: Plug.Conn.t()
+  def get_spec(conn, _params), do: json(conn, %{"data" => chain_spec()})
+
+  defp chain_spec() do
+    ChainSpec.get_all()
+    |> Map.drop(@chain_spec_removed_keys)
+    |> rename_keys(@chain_spec_renamed_keys)
+    |> Map.new(fn
+      {k, v} when is_integer(v) -> {k, Integer.to_string(v)}
+      {k, v} when k in @chain_spec_hex_fields -> {k, Utils.hex_encode(v)}
+      {k, v} -> {k, v}
+    end)
+  end
+
+  defp rename_keys(config, renamed_keys) do
+    renamed_keys |> Enum.reduce(config, fn {old_key, new_key}, config ->
+      case Map.get(config, old_key) do
+        nil -> config
+        value -> Map.put_new(config, new_key, value) |> Map.delete(old_key)
+      end
+    end)
+  end
+end

lib/beacon_api/router.ex

@@ -17,6 +17,10 @@ defmodule BeaconApi.Router do
       get("/states/:state_id/finality_checkpoints", BeaconController, :get_finality_checkpoints)
     end
 
+    scope "config" do
+      get("/spec", ConfigController, :get_spec)
+    end
+
     scope "/node" do
       get("/health", NodeController, :health)
       get("/identity", NodeController, :identity)

lib/chain_spec/chain_spec.ex

@@ -19,6 +19,8 @@ defmodule ChainSpec do
   # NOTE: this only works correctly for Capella
   def get(name), do: get_config().get(name)
 
+  def get_all(), do: get_config().get_all()
+
   def get_genesis_validators_root() do
     Application.fetch_env!(:lambda_ethereum_consensus, __MODULE__)
     |> Keyword.fetch!(:genesis_validators_root)