From 47e279ece7c0f07fdc669407bd124ebd55adccb9 Mon Sep 17 00:00:00 2001
From: themadbit <marktanui75@gmail.com>
Date: Thu, 5 Jun 2025 19:45:23 +0300
Subject: [PATCH] modularize NIX_CONFIG

---
 overview/content-types/config-item.nix | 20 ++++++++++++++++++
 overview/content-types/nix-config.nix  | 29 ++++++++++++++++++++++++++
 overview/default.nix                   | 21 ++++++++++++++++++-
 3 files changed, 69 insertions(+), 1 deletion(-)
 create mode 100644 overview/content-types/config-item.nix
 create mode 100644 overview/content-types/nix-config.nix

diff --git a/overview/content-types/config-item.nix b/overview/content-types/config-item.nix
new file mode 100644
index 000000000..bd05b68a7
--- /dev/null
+++ b/overview/content-types/config-item.nix
@@ -0,0 +1,20 @@
+{
+  name,
+  config,
+  lib,
+  ...
+}:
+let
+  inherit (lib) mkOption types;
+in
+{
+  options = {
+    name = mkOption {
+      type = types.str;
+      default = name;
+    };
+    value = mkOption {
+      type = with types; either str (listOf str);
+    };
+  };
+}
diff --git a/overview/content-types/nix-config.nix b/overview/content-types/nix-config.nix
new file mode 100644
index 000000000..726d1126c
--- /dev/null
+++ b/overview/content-types/nix-config.nix
@@ -0,0 +1,29 @@
+{
+  name,
+  config,
+  lib,
+  ...
+}:
+let
+  inherit (lib) mkOption types;
+in
+{
+  options = {
+    __toString = mkOption {
+      type = with types; functionTo str;
+      readOnly = true;
+      default =
+        self:
+        let
+          separator = "'$'\\n''";
+          concatSettings = lib.concatStringsSep separator (
+            lib.map (attrs: "${attrs.name} = ${toString attrs.value}") self.settings
+          );
+        in
+        "NIX_CONFIG='${concatSettings}'";
+    };
+    settings = mkOption {
+      type = with types; listOf (submodule ./config-item.nix);
+    };
+  };
+}
diff --git a/overview/default.nix b/overview/default.nix
index 869a410e2..e227e234a 100644
--- a/overview/default.nix
+++ b/overview/default.nix
@@ -268,6 +268,25 @@ let
         openPorts = demoSystem.config.networking.firewall.allowedTCPPorts;
         # The port that is forwarded to the host so that the user can access the demo service.
         servicePort = (builtins.head openPorts);
+        nix-config = eval {
+          imports = [ ./content-types/nix-config.nix ];
+          settings = [
+            {
+              name = "substituters";
+              value = [
+                "https://cache.nixos.org/"
+                "https://ngi.cachix.org/"
+              ];
+            }
+            {
+              name = "trusted-public-keys";
+              value = [
+                "cache.nixos.org-1:6nchdd59x431o0gwypbmraurkbj16zpmqfgspcdshjy="
+                "ngi.cachix.org-1:n+cal72roc3qqulxihpv+tw5t42whxmmhpragkrsrow="
+              ];
+            }
+          ];
+        };
       in
       ''
         ${heading 2 "demo" "Try the service in a VM"}
@@ -291,7 +310,7 @@ let
           </li>
           <li>
             <strong>Enable binary substituters</strong>
-              <pre><code>NIX_CONFIG='substituters = https://cache.nixos.org/ https://ngi.cachix.org/'$'\n'''trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= ngi.cachix.org-1:n+CAL72ROC3qQuLxIHpV+Tw5t42WhXmMhprAGkRSrOw='</code></pre>
+              <pre><code>${nix-config}</code></pre>
               <pre><code>export NIX_CONFIG</code></pre>
           </li>
           <li>