treewide: Migrate to the new dream2nix API

flake.nix

@@ -2,7 +2,7 @@
   description = "tlater.net web server";
 
   inputs = {
-    nixpkgs.url = "github:nixos/nixpkgs/nixos-23.05";
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-23.11";
     dream2nix.url = "github:nix-community/dream2nix";
 
     fenix = {
@@ -16,21 +16,28 @@
     nixpkgs,
     dream2nix,
     fenix,
-  } @ flake-inputs: let
+  }: let
     # At the moment, we only deploy to x86_64-linux. Update when we
     # care about another platform.
     system = "x86_64-linux";
-    flakeOutputs = nixpkgs.lib.callPackageWith flake-inputs (import ./nix/packages.nix) {inherit system;};
+    pkgs = nixpkgs.legacyPackages.${system};
+    fenixPkgs = fenix.packages.${system};
+    ownPkgs = self.packages.${system};
   in {
-    packages.${system} = {
-      server = flakeOutputs.packages.${system}.tlaternet-webserver;
-      templates = flakeOutputs.packages.${system}.tlaternet;
+    packages.${system} = dream2nix.lib.importPackages {
+      projectRoot = ./.;
+      projectRootFile = "flake.nix";
+      packagesDir = ./packages;
+      packageSets = {
+        nixpkgs = pkgs;
+        fenix = fenixPkgs;
+      };
     };
 
     apps.${system} = {
       default = let
-        inherit (self.packages.${system}) server templates;
-        inherit (nixpkgs.legacyPackages.${system}) writeShellScript;
+        inherit (ownPkgs) server templates;
+        inherit (pkgs) writeShellScript;
       in {
         type = "app";
         program = builtins.toString (writeShellScript "tlaternet-webserver" ''
@@ -39,11 +46,7 @@
       };
 
       update = let
-        update-script = nixpkgs.legacyPackages.${system}.callPackage ./nix/update.nix {
-          cargo = flakeOutputs.rust-toolchain.cargo;
-          npm = nixpkgs.legacyPackages.${system}.nodePackages_latest.npm;
-          npm-check-updates = self.packages.${system}.templates.dependencies.npm-check-updates;
-        };
+        update-script = pkgs.callPackage ./nix/update.nix {inherit self;};
       in {
         type = "app";
         program = "${update-script}/bin/update";
@@ -53,17 +56,9 @@
     nixosModules.default = import ./nix/module.nix {inherit self system;};
 
     devShells.${system} = {
-      templates = flakeOutputs.devShells.${system}.tlaternet.overrideAttrs (old: {
-        buildInputs = with nixpkgs.legacyPackages.${system};
-          [
-            yj
-          ]
-          ++ old.buildInputs;
-      });
-
-      server = nixpkgs.legacyPackages.${system}.mkShell {
+      server = pkgs.mkShell {
         packages = [
-          (flakeOutputs.rust-toolchain.withComponents [
+          (fenixPkgs.stable.withComponents [
             "rustc"
             "cargo"
             "rustfmt"
@@ -73,14 +68,13 @@
             "rust-src"
             "rust-analysis"
           ])
-          fenix.packages.${system}.rust-analyzer
+          fenixPkgs.rust-analyzer
         ];
       };
     };
 
     checks.${system} = import ./nix/checks {
-      inherit self system;
-      pkgs = nixpkgs.legacyPackages.${system};
+      inherit self system pkgs;
     };
   };
 }