Merge pull request #4650 from flouthoc/cache-to-with-mount

stage_executor,cache-to: attempt to push cache only when `cacheKey` is valid

imagebuildah/stage_executor.go

@@ -1428,7 +1428,7 @@ func (s *StageExecutor) Execute(ctx context.Context, base string) (imgID string,
 		// Try to push this cache to remote repository only
 		// if cache was present on local storage and not
 		// pulled from remote source while processing this
-		if len(s.executor.cacheTo) != 0 && (!pulledAndUsedCacheImage || cacheID == "") {
+		if len(s.executor.cacheTo) != 0 && (!pulledAndUsedCacheImage || cacheID == "") && needsCacheKey {
 			logCachePush(cacheKey)
 			if err = s.pushCache(ctx, imgID, cacheKey); err != nil {
 				return "", nil, err

tests/bud.bats

@@ -4619,6 +4619,7 @@ ADD somefile somefile
 FROM alpine
 RUN echo hello
 COPY --from=0 hello hello
+RUN --mount=type=cache,id=YfHI60aApFM-target,target=/target echo world > /target/hello
 _EOF
 
   start_registry
@@ -4636,7 +4637,7 @@ _EOF
   run printf "STEP 5/5: ADD somefile somefile\n--> Pushing cache"
   step4=$output
   # First run step in second stage should not be pushed since its already pushed
-  run printf "STEP 2/3: RUN echo hello\n--> Using cache"
+  run printf "STEP 2/4: RUN echo hello\n--> Using cache"
   step5=$output
   # Last step is `COPY --from=0 hello hello' so it must be committed and pushed
   # actual output is `[2/2] STEP 3/3: COPY --from=0 hello hello\n[2/2] COMMIT test\n-->Pushing cache`
@@ -4672,7 +4673,7 @@ _EOF
   run printf "STEP 5/5: ADD somefile somefile\n--> Cache pulled from remote"
   step4=$output
   # First run step in second stage should not be pulled since its already pulled
-  run printf "STEP 2/3: RUN echo hello\n--> Using cache"
+  run printf "STEP 2/4: RUN echo hello\n--> Using cache"
   step5=$output
   run printf "COPY --from=0 hello hello\n--> Cache pulled from remote"
   step6=$output