From 904cb233f3572b7bf4ff63be402b11a6be48aa46 Mon Sep 17 00:00:00 2001
From: bluepython508 <16466646+bluepython508@users.noreply.github.com>
Date: Thu, 26 Sep 2024 09:09:11 +0100
Subject: [PATCH] More principled initial peers

---
 .envrc            |  1 +
 config/config.exs |  4 ++++
 flake.nix         | 17 +++++++++++++++--
 lib/agent.ex      |  7 +++++++
 lib/frajtano.ex   |  1 +
 mix.exs           |  7 ++++++-
 6 files changed, 34 insertions(+), 3 deletions(-)
 create mode 100644 config/config.exs

diff --git a/.envrc b/.envrc
index 2854f9b..3b2e73e 100644
--- a/.envrc
+++ b/.envrc
@@ -2,3 +2,4 @@ use flake
 
 export RELEASE_NODE=frajtano-test@$(cat /etc/hostname)
 export FRAJTANO_DIR=$PWD/.frajtano_state
+export FRAJTANO_CONFIG=$PWD/config/config.exs
diff --git a/config/config.exs b/config/config.exs
new file mode 100644
index 0000000..a238fac
--- /dev/null
+++ b/config/config.exs
@@ -0,0 +1,4 @@
+import Config
+
+config :frajtano,
+  initial_peers: []
diff --git a/flake.nix b/flake.nix
index f371f6e..bec7d31 100644
--- a/flake.nix
+++ b/flake.nix
@@ -40,10 +40,22 @@
         dir = lib.mkOption {
           description = "directory in which to place the listening socket";
           default = "${config.home.homeDirectory}/.ssh/frajtano";
+          type = lib.types.path;
+        };
+        initialPeers = lib.mkOption {
+          description = "initially spawned peers - will be passed to /usr/bin/env";
+          type = with lib.types; listOf (listOf str);
+          default = [];
         };
       };
 
-      config = lib.mkIf cfg.enable {
+      config = let
+        peers = lib.strings.concatMapStringsSep ", " (args: ''{:spawn, {"${pkgs.coreutils}/bin/env", [${lib.concatMapStringsSep ", " (s: ''~S{${s}}'') args}]}}'') cfg.initialPeers;
+        configFile = pkgs.writeText "config.exs" ''
+          import Config
+          config :frajtano, initial_peers: [${peers}]
+        '';
+      in lib.mkIf cfg.enable {
         home.sessionVariables.FRAJTANO_DIR = cfg.dir;
         home.packages = [self.packages.${pkgs.system}.default];
 
@@ -51,7 +63,7 @@
           Unit.Description = "frajtano";
           Unit.After = ["default.target"];
           Service.Type = "notify";
-          Service.Environment = ["'FRAJTANO_DIR=${cfg.dir}'"];
+          Service.Environment = ["'FRAJTANO_DIR=${cfg.dir}'" "'FRAJTANO_CONFIG=${configFile}'"];
           Service.ExecSearchPath = ["${self.packages.${pkgs.system}.default}/bin"];
           Service.ExecStart = "frajtano start";
           Install.WantedBy = ["default.target"];
@@ -62,6 +74,7 @@
           config = {
             EnvironmentVariables = {
               FRAJTANO_DIR = cfg.dir;
+              FRAJTANO_CONFIG = configFile;
             };
             ProgramArguments = ["${self.packages.${pkgs.system}.default}/bin/frajtano" "start"];
             RunAtLoad = true;
diff --git a/lib/agent.ex b/lib/agent.ex
index fb89c5d..5fc0ab3 100644
--- a/lib/agent.ex
+++ b/lib/agent.ex
@@ -1,6 +1,7 @@
 defmodule Frajtano.Agent do
   alias Frajtano.Peer
   use GenServer
+  require Logger
 
   def start_link(args) do
     GenServer.start_link(__MODULE__, nil, [{:name, __MODULE__} | args])
@@ -14,6 +15,12 @@ defmodule Frajtano.Agent do
     }
   end
 
+  def initial_peers() do
+    initial_peers = Application.fetch_env!(:frajtano, :initial_peers)
+    |> Enum.map(&GenServer.call(__MODULE__, {:add_peer, &1}))
+    Logger.info("Started initial peers: #{inspect initial_peers}")
+  end
+
   # select: list of specs, where specs are a tuple of match, guards, and outputs
   # match is {key, pid, value}, :"$1" is a match variable
   def peer_paths() do
diff --git a/lib/frajtano.ex b/lib/frajtano.ex
index c112834..72019bf 100644
--- a/lib/frajtano.ex
+++ b/lib/frajtano.ex
@@ -22,6 +22,7 @@ defmodule Frajtano.Supervisor do
   	  Frajtano.Agent,
   	  {Task.Supervisor, name: Frajtano.ClientSupervisor},
   	  {Frajtano.Listener, [Application.fetch_env!(:frajtano, :listen_path)]},
+  	  {Task, &Frajtano.Agent.initial_peers/0},
   	  :systemd.ready(),
   	]
 
diff --git a/mix.exs b/mix.exs
index b63208b..d51553d 100644
--- a/mix.exs
+++ b/mix.exs
@@ -7,7 +7,12 @@ defmodule Frajtano.MixProject do
       version: "0.0.1",
       elixir: "~> 1.16",
       start_permanent: Mix.env() == :prod,
-      deps: deps()
+      deps: deps(),
+      releases: [
+        frajtano: [
+          config_providers: [{Config.Reader, {:system, "FRAJTANO_CONFIG", ""}}]
+        ],
+      ]
     ]
   end