Use raw strings rather than B64, assume paths don't have }

.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

config/config.exs

@@ -0,0 +1,4 @@
+import Config
+
+config :frajtano,
+  initial_peers: []

default.nix

@@ -51,7 +51,7 @@
 
     case "''${1:-}" in
       assimilate)
-        run rpc ":ok = \"$(echo -n "$2" | ${pkgs.coreutils}/bin/base64)\" |> Base.decode64!() |> Frajtano.Agent.assimilate()"
+        run rpc ":ok = ~S{$2} |> Frajtano.Agent.assimilate()"
       ;;
       spawn)
         shift

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;

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

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(),
   	]
 

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