stage_executor: history should include heredoc summary correctly

getCreatedBy ignores heredoc summary when build args are specified
following PR makes sure the behaviour is correct.

Also test is modified to make sure buildah correctly burst cache if
heredoc content is changed.

Closes: containers/podman#25469

Signed-off-by: flouthoc <[email protected]>

Author: flouthoc

imagebuildah/stage_executor.go

@@ -1943,17 +1943,20 @@ func (s *StageExecutor) getCreatedBy(node *parser.Node, addedContentSummary stri
 		if len(node.Original) > 4 {
 			shArg = node.Original[4:]
 		}
-		if buildArgs != "" {
-			return "|" + strconv.Itoa(len(strings.Split(buildArgs, " "))) + " " + buildArgs + " /bin/sh -c " + shArg + appendCheckSum, nil
-		}
-		result := "/bin/sh -c " + shArg
+
+		heredoc := ""
+		result := ""
 		if len(node.Heredocs) > 0 {
 			for _, doc := range node.Heredocs {
 				heredocContent := strings.TrimSpace(doc.Content)
-				result = result + "\n" + heredocContent
+				heredoc = heredoc + "\n" + heredocContent
 			}
 		}
-		return result + appendCheckSum, nil
+		if buildArgs != "" {
+			result = result + "|" + strconv.Itoa(len(strings.Split(buildArgs, " "))) + " " + buildArgs + " "
+		}
+		result = result + "/bin/sh -c " + shArg + heredoc + appendCheckSum
+		return result, nil
 	case "ADD", "COPY":
 		destination := node
 		for destination.Next != nil {

tests/bud.bats

@@ -542,6 +542,44 @@ _EOF
   expect_output --substring "Cache burst add diff"
 }
 
+@test "bud --layers should not hit cache if heredoc is changed - with ARG" {
+  _prefetch alpine
+  local contextdir=${TEST_SCRATCH_DIR}/bud/platform
+  mkdir -p $contextdir
+
+  cat > $contextdir/Dockerfile << _EOF
+FROM alpine
+ARG key=value
+RUN <<EOF
+echo "Cache burst" >> /hello
+echo "Cache burst second line" >> /hello
+EOF
+RUN cat hello
+_EOF
+
+  # on first run since there is no cache so `Cache burst` must be printed
+  run_buildah build $WITH_POLICY_JSON --layers -t source -f $contextdir/Dockerfile
+  expect_output --substring "Cache burst second line"
+
+  # on second run since there is cache so `Cache burst` should not be printed
+  run_buildah build $WITH_POLICY_JSON --layers -t source -f $contextdir/Dockerfile
+  # output should not contain cache burst
+  assert "$output" !~ "Cache burst second line"
+
+  cat > $contextdir/Dockerfile << _EOF
+FROM alpine
+ARG key=value
+RUN <<EOF
+echo "Cache burst add diff" >> /hello
+EOF
+RUN cat hello
+_EOF
+
+  # on third run since we have changed heredoc so `Cache burst` must be printed.
+  run_buildah build $WITH_POLICY_JSON --layers -t source -f $contextdir/Dockerfile
+  expect_output --substring "Cache burst add diff"
+}
+
 @test "bud build with heredoc content" {
   _prefetch alpine
   run_buildah build -t heredoc $WITH_POLICY_JSON -f $BUDFILES/heredoc/Containerfile .