Parser errors on dockerfiles without instructions

See moby/moby#38487 for more discussion. Signed-off-by: Natasha Jarus <[email protected]>
moby · Jan 4, 2019 · 2ec7d53 · 2ec7d53
1 parent c471ab8
commit 2ec7d53
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diff --git a/frontend/dockerfile/parser/parser.go b/frontend/dockerfile/parser/parser.go
@@ -275,6 +275,11 @@ func Parse(rwc io.Reader) (*Result, error) {
 	if len(warnings) > 0 {
 		warnings = append(warnings, "[WARNING]: Empty continuation lines will become errors in a future release.")
 	}
+
+	if root.StartLine < 0 {
+		return nil, errors.New("file with no instructions.")
+	}
+
 	return &Result{
 		AST:         root,
 		Warnings:    warnings,

diff --git a/frontend/dockerfile/parser/testfiles-negative/empty_dockerfile/Dockerfile b/frontend/dockerfile/parser/testfiles-negative/empty_dockerfile/Dockerfile
diff --git a/frontend/dockerfile/parser/testfiles-negative/only_comments/Dockerfile b/frontend/dockerfile/parser/testfiles-negative/only_comments/Dockerfile
@@ -0,0 +1,3 @@
+# Hello
+# These are just comments
+