build: merge helm indexes instead of recreating for every release (really)

    A new helm repo index was created from scratch for every new release
    which meant that the release timestamps in the index were basically all
    identical.

    This change intends to fix that by merging the new index with the
    existing one

The first attempt to fix this (PR rook#16033) did not work properly.
This change is intended to fix the issue for good by closing the gap the
previuous PR has left.

    Fixes: rook#15604

Co-Authored-By: Travis Nielsen <tnielsen@redhat.com>
Signed-off-by: Michael Adam <obnox@samba.org>

Author: obnoxxx

build/release/Makefile

@@ -120,9 +120,14 @@ HELM_URL := $(HELM_BASE_URL)/$(HELM_CHANNEL)
 promote.helm: $(HELM)
 #	copy existing charts to a temp dir, then combine with new charts, reindex, and upload
 	$(S3_SYNC) s3://$(HELM_S3_BUCKET)/$(HELM_CHANNEL) $(HELM_TEMP)
+	# delete unnecessary files:
+	rm -fr $(HELM_TEMP)/*tgz
+	# rename current index to distinguish the previous file.
+	mv $(HELM_TEMP)/index.yaml $(HELM_TEMP)/previous_index.yaml
 	$(S3_SYNC) s3://$(S3_BUCKET)/build/$(BRANCH_NAME)/$(VERSION)/charts $(HELM_TEMP)
-	$(HELM) repo index --url $(HELM_URL) --merge $(HELM_TEMP)/index.yaml $(HELM_TEMP)
-	$(S3_SYNC_DEL) $(HELM_TEMP) s3://$(HELM_S3_BUCKET)/$(HELM_CHANNEL)
+	$(HELM) repo index --url $(HELM_URL) --merge $(HELM_TEMP)/previous_index.yaml $(HELM_TEMP)
+	rm -f $(HELM_TEMP)/previous_index.yaml
+	$(S3_SYNC) $(HELM_TEMP) s3://$(HELM_S3_BUCKET)/$(HELM_CHANNEL)
 	rm -fr $(HELM_TEMP)
 
 # set the helm cart version number.