try diffoscope

Author: HarryGogonis

.github/workflows/test.yml

@@ -19,10 +19,6 @@ jobs:
           kustomizations: |-
             testdata/prod
             testdata/stage
-      - run: echo "${{ steps.test-action.outputs.diff }}"
       - uses: mshick/add-pr-comment@v2
         with:
-          message: |
-            ```diff
-            ${{ steps.test-action.outputs.diff }}
-            ```
+          message: ${{ steps.test-action.outputs.diff }}

README.md

@@ -1 +1,4 @@
-# GitHub Action for Kustomize Build+Diff
+# GitHub Action for Kustomize Build+Diff
+
+docker run --rm -t -w $(pwd) -v $(pwd):$(pwd):ro \
+            registry.salsa.debian.org/reproducible-builds/diffoscope --exclude-directory-metadata=yes testdata testdata2

entrypoint.sh

@@ -20,13 +20,20 @@ git config --global --add safe.directory "$GITHUB_WORKSPACE"
 build "$INPUT_BASE_REF"
 build "$INPUT_HEAD_REF"
 
-diffoscope "$build_dir/$INPUT_BASE_REF" "$build_dir/$INPUT_HEAD_REF" --markdown diff.md --exclude-directory-metadata=recursive || true
-output=$(cat diff.md)
+base_ref_build_dir="$build_dir/$INPUT_BASE_REF"
+head_ref_build_dir="$build_dir/$INPUT_HEAD_REF"
 
-# If escaped output is longer than 65000 characters return "output to large to print as a github comment"
-if [ ${#output} -gt 65000 ]; then
-	output="Output is greater than 65000 characters, and therefore too large to print as a github comment."
-fi
+set +e
+for target in $INPUT_KUSTOMIZATIONS; do
+	diffoscope "$base_ref_build_dir/$target" "$head_ref_build_dir/$target" \
+		--markdown - \
+		--exclude-directory-metadata=yes | tee -a diff.md
+done
+
+set -e
+
+# Formatting hacks
+output=$(cat diff.md | sed "s|$base_ref_build_dir/||" | sed '/Comparing/ s/&.*$//' | sed "s|^#\{2,\} Comparing| Comparing|" | sed "s|^# Comparing|## Comparing|")
 
 {
 	echo 'diff<<EOF'