From 6682530ea572201b16454ff6e8164329acc560d9 Mon Sep 17 00:00:00 2001
From: Samuel Meenzen <samuel@meenzen.net>
Date: Wed, 16 Jul 2025 17:16:52 +0200
Subject: [PATCH] feat: add commit timestamp to oci-image

---
 nix/pkgs/oci-image/default.nix | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/nix/pkgs/oci-image/default.nix b/nix/pkgs/oci-image/default.nix
index f27c45c0..1224d41c 100644
--- a/nix/pkgs/oci-image/default.nix
+++ b/nix/pkgs/oci-image/default.nix
@@ -1,6 +1,7 @@
 # Keep sorted
 { default
 , dockerTools
+, inputs
 , lib
 , pkgs
 }:
@@ -13,10 +14,27 @@ let
       })
     ];
   };
+
+  # This is a unix timestamp of the last commit
+  timestamp = inputs.self.lastModified;
+
+  # Convert the timestamp to an ISO 8601 string
+  iso = builtins.readFile (
+    pkgs.runCommand "timestamp" {
+      when = timestamp;
+      nativeBuildInputs = [ pkgs.coreutils ];
+    } ''
+      date -u -d "@$when" +%Y-%m-%dT%H:%M:%SZ > $out
+    ''
+  );
+
+  # Remove trailing newline
+  isoTrimmed = lib.strings.trim iso;
 in
 dockerTools.buildImage {
   name = default.pname;
   tag = "next";
+  created = isoTrimmed;
   copyToRoot = [
     dockerTools.caCertificates
   ];