refactor(exts): replace nixpkgs-oldstable with specific overlay packages

Use overlay instead of passing full nixpkgs-oldstable to avoid exposing
entire old nixpkgs attribute set. Now provides specific packages
(curl_8_4, v8_oldstable) through overlay.

Author: yvan-sraka

nix/ext/pg_jsonschema/default.nix

@@ -82,6 +82,11 @@ let
         cargo pgrx init --pg${lib.versions.major postgresql.version} $PGRX_HOME/${lib.versions.major postgresql.version}/bin/pg_config
       '';
 
+      # Tests are disabled for specific versions because pgrx tests require
+      # `cargo pgrx install --test` which fails in the nix sandbox due to
+      # write permission restrictions. Unlike pg_graphql which has a custom
+      # installcheck script, pg_jsonschema only has pgrx cargo tests.
+      # See: https://github.com/supabase/pg_jsonschema/blob/v0.3.3/src/lib.rs#L45-L195
       doCheck =
         !(builtins.elem version [
           "0.2.0"

nix/ext/pg_net.nix

@@ -7,11 +7,11 @@
   libuv,
   makeWrapper,
   switch-ext-version,
-  nixpkgs-oldstable,
+  curl_8_6,
 }:
 
 let
-  curl = nixpkgs-oldstable.curl;
+  curl = curl_8_6;
 in
 let
   pname = "pg_net";

nix/ext/plv8/default.nix

@@ -2,7 +2,6 @@
   stdenv,
   lib,
   fetchFromGitHub,
-  # v8,
   perl,
   postgresql,
   # For passthru test on various systems, and local development on macos
@@ -14,7 +13,7 @@
   buildEnv,
   nodejs_20,
   libcxx,
-  nixpkgs-oldstable,
+  v8_oldstable,
 }:
 
 let
@@ -37,7 +36,7 @@ let
   );
 
   # plv8 3.1 requires an older version of v8 (we cannot use nodejs.libv8)
-  inherit (nixpkgs-oldstable) v8;
+  v8 = v8_oldstable;
 
   # Build function for individual versions
   build =

nix/nixpkgs.nix

@@ -11,10 +11,21 @@
           (import inputs.rust-overlay)
           self.overlays.default
           (_final: _prev: {
-            nixpkgs-oldstable = import inputs.nixpkgs-oldstable {
+            # Provide older versions of packages required by some extensions
+            oldstable = import inputs.nixpkgs-oldstable {
               inherit system;
               config.allowUnfree = true;
             };
+            curl_8_6 =
+              (import inputs.nixpkgs-oldstable {
+                inherit system;
+                config.allowUnfree = true;
+              }).curl;
+            v8_oldstable =
+              (import inputs.nixpkgs-oldstable {
+                inherit system;
+                config.allowUnfree = true;
+              }).v8;
           })
         ];
       };