multi-ssh/flake.nix

{
  description = "Flake of https://dev.stupstech.de/Mr_Steppy/multi-ssh";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.05";
    rust-overlay.url = "github:oxalica/rust-overlay";
  };

  outputs = { self, nixpkgs, rust-overlay, ... }:
    let
      systems = nixpkgs.lib.systems.flakeExposed;
      forAllSystems = nixpkgs.lib.genAttrs systems;
    in
    {
      packages = forAllSystems (system:
        let
          overlays = [ rust-overlay.overlays.default ];
          pkgs = import nixpkgs { inherit system; overlays = overlays; };
          rustToolchain = pkgs.rust-bin.stable."1.90.0".minimal;
          rustPlatform = pkgs.makeRustPlatform { cargo = rustToolchain; rustc = rustToolchain; };
        in {
          multiSsh = rustPlatform.buildRustPackage {
            pname = "multi-ssh";
            version = (builtins.fromTOML (builtins.readFile ./Cargo.toml)).package.version;
            src = ./.;
            cargoLock = {
              lockFile = ./Cargo.lock;
            };
            nativeCheckInputs = [ pkgs.python3 ];
            release = true;
          };
          default = self.packages.${system}.multiSsh;
        }
      );

      apps = forAllSystems (system:
        let
          pkg = self.packages.${system}.multiSsh;
        in {
          default = {
            type = "app";
            program = "${pkg}/bin/multi-ssh";
          };
        }
      );

      nixosModules.multiSsh = { lib, pkgs, config, ... }: {
        options = {
          programs.multiSsh = {
            enable = lib.mkEnableOption "multi-ssh";
            editor = lib.mkOption {
              type = lib.types.nullOr lib.types.str;
              description = "Editor to forward to multi-ssh (MSSH_EDITOR). If null, the variable is not set.";
              default = null;
            };
            package = lib.mkOption {
              type = lib.types.package;
              description = "Derivation to install for multi-ssh";
              default = self.packages.${pkgs.system}.multiSsh;
            };
            servers = {
              local = {
                dir = lib.mkOption {
                  type = lib.types.nullOr lib.types.str;
                  default = null;
                  description = ''Local server directory, relative to the user's HOME. If set, a local entry ".:<dir>" is added to MSSH_SERVERS.'';
                };
              };
              server = lib.mkOption {
                type = lib.types.attrsOf (lib.types.submodule ({ name, ... }: {
                  options = {
                    dir = lib.mkOption {
                      type = lib.types.str;
                      description = "Server directory for ${name} (remote ssh host), as a string.";
                    };
                  };
                }));
                default = {};
                description = "Attribute set of servers where each attribute name is the ssh host and its value provides a 'dir' string.";
              };
            };
            msshAlias = lib.mkOption {
              type = lib.types.bool;
              default = true;
              description = "If true, install an 'mssh' wrapper (alias) that calls 'multi-ssh' and sets env vars.";
            };
          };
        };

        config = lib.mkIf config.programs.multiSsh.enable (let
          # Build MSSH_SERVERS from options
          serverEntries = lib.mapAttrsToList (name: value: "${name}:${value.dir}") config.programs.multiSsh.servers.server;
          localEntry = lib.optional (config.programs.multiSsh.servers.local.dir != null) ".:${config.programs.multiSsh.servers.local.dir}";
          msshServers = lib.concatStringsSep "," (localEntry ++ serverEntries);

          # wrapper that sets env and execs the real binary (installed as 'multi-ssh')
          multiSshWrapper = pkgs.writeShellScriptBin "multi-ssh" ''
            #!${pkgs.runtimeShell}
            ${lib.optionalString (config.programs.multiSsh.editor != null) ''export MSSH_EDITOR="${config.programs.multiSsh.editor}"''}
            ${lib.optionalString (msshServers != "") ''export MSSH_SERVERS="${msshServers}"''}
            exec ${config.programs.multiSsh.package}/bin/multi-ssh "$@"
          '';

          # optional 'mssh' alias that delegates to the wrapped 'multi-ssh'
          msshWrapper = pkgs.writeShellScriptBin "mssh" ''
            #!${pkgs.runtimeShell}
            exec ${multiSshWrapper}/bin/multi-ssh "$@"
          '';
        in {
          environment.systemPackages = [
            multiSshWrapper
          ] ++ lib.optional config.programs.multiSsh.msshAlias msshWrapper;
        });
      };
    };
}