From b1162ce7a883993e1219de8f2dbdb0f4ede585c1 Mon Sep 17 00:00:00 2001
From: matt1432 <matt@nelim.org>
Date: Tue, 9 Apr 2024 20:33:00 -0400
Subject: [PATCH] feat(updateImage): check version before downloading image

---
 modules/arion/default.nix | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/modules/arion/default.nix b/modules/arion/default.nix
index 41da620..c132960 100644
--- a/modules/arion/default.nix
+++ b/modules/arion/default.nix
@@ -103,17 +103,24 @@ in {
         runtimeInputs = [
           (writeShellApplication {
             name = "pullImage";
-            runtimeInputs = [nix-prefetch-docker];
+            runtimeInputs = [nix-prefetch-docker skopeo];
             text = ''
               FILE="$1"
 
               IMAGE=$(sed -n 's/.*imageName = "\([^"]*\).*/\1/p' "$FILE")
               TAG=$(sed -n 's/.*finalImageTag = "\([^"]*\).*/\1/p' "$FILE")
+              CURRENT_DIGEST=$(sed -n 's/.*imageDigest = "\([^"]*\).*/\1/p' "$FILE")
+              NEW_DIGEST=$(skopeo inspect "docker://$IMAGE:$TAG" | jq '.Digest' -r)
+
               echo "$IMAGE $TAG"
 
               if ! grep "Locked" "$FILE"; then
-                  PREFETCH=$(nix-prefetch-docker "$IMAGE" "$TAG")
-                  echo -e "pkgs:\npkgs.dockerTools.pullImage $PREFETCH" > "$FILE"
+                  if [[ "$CURRENT_DIGEST" == "$NEW_DIGEST" ]]; then
+                      echo "Already up-to-date"
+                  else
+                      PREFETCH=$(nix-prefetch-docker "$IMAGE" "$TAG")
+                      echo -e "pkgs:\npkgs.dockerTools.pullImage $PREFETCH" > "$FILE"
+                  fi
               fi
             '';
           })