fix: cache: serialize legacy import field (#603)

Fixes #592 by serializing the `wasLegacyImport` field to ensure that the
cache records the correct value when an image has it set.

Includes a test based on Serge's description in #592.

The symptom is an error "cache miss because layer definition was
changed" when the definition could not have changed since build.
This happens during multi file builds in builds with dependencies, and
in build-then-publish flows, where the build will be fine but the
publish will fail with the same error.

Using `--debug` to show the cache mismatch shows that somewhere along
the line, the layer is being serialized with the wrong default value
when writing to the cache.

Needs to change currentCacheVersion to ensure compatibility, see the
TestCacheEntryChanged function comment for more info.

Signed-off-by: Michael McCracken <mikmccra@cisco.com>

pkg/stacker/build.go

@@ -118,7 +118,7 @@ func (b *Builder) updateOCIConfigForOutput(sf *types.Stackerfile, s types.Storag
 	}
 
 	inDir := types.InternalStackerDir
-	if l.WasLegacyImport() {
+	if l.WasLegacyImport {
 		inDir = types.LegacyInternalStackerDir
 	}
 
@@ -372,7 +372,9 @@ func (b *Builder) build(s types.Storage, file string) error {
 
 		log.Infof("preparing image %s...", name)
 		inDir := types.InternalStackerDir
-		if l.WasLegacyImport() {
+		if l.WasLegacyImport {
+			log.Debugf("image %s uses legacy import syntax, will also mount imports at %s",
+				name, types.LegacyInternalStackerDir)
 			inDir = types.LegacyInternalStackerDir
 		}
 

pkg/stacker/cache.go

@@ -22,7 +22,7 @@ import (
 	"stackerbuild.io/stacker/pkg/types"
 )
 
-const currentCacheVersion = 13
+const currentCacheVersion = 14
 
 type ImportType int
 

pkg/stacker/cache_test.go

@@ -125,5 +125,5 @@ func TestCacheEntryChanged(t *testing.T) {
 	// This test works because the type information is included in the
 	// hashstructure hash above, so using a zero valued CacheEntry is
 	// enough to capture changes in types.
-	assert.Equal(uint64(0x4ef432528243e356), h)
+	assert.Equal(uint64(0xa26696f335211127), h)
 }

pkg/types/layer.go

@@ -260,7 +260,7 @@ type Layer struct {
 	OS              *string           `yaml:"os" json:"os,omitempty"`
 	Arch            *string           `yaml:"arch" json:"arch,omitempty"`
 	Bom             *Bom              `yaml:"bom" json:"bom,omitempty"`
-	wasLegacyImport bool
+	WasLegacyImport bool              `yaml:"was_legacy_import" json:"was_legacy_import,omitempty"`
 }
 
 func parseLayers(referenceDirectory string, lms yaml.MapSlice, requireHash bool) (map[string]Layer, error) {
@@ -369,7 +369,7 @@ func parseLayers(referenceDirectory string, lms yaml.MapSlice, requireHash bool)
 		if len(layer.LegacyImport) != 0 {
 			layer.Imports = layer.LegacyImport
 			layer.LegacyImport = nil
-			layer.wasLegacyImport = true
+			layer.WasLegacyImport = true
 		}
 
 		ret[name], err = layer.absolutify(referenceDirectory)
@@ -442,11 +442,6 @@ func (l Layer) absolutify(referenceDirectory string) (Layer, error) {
 	return ret, nil
 }
 
-// WasLegacyImport - return true if this layer used legacy 'import' directive.
-func (l Layer) WasLegacyImport() bool {
-	return l.wasLegacyImport
-}
-
 func requireImportHash(imports Imports) error {
 	for _, imp := range imports {
 		url, err := NewDockerishUrl(imp.Path)

pkg/types/stackerfile.go

@@ -269,7 +269,7 @@ func NewStackerfile(stackerfile string, validateHash bool, substitutions []strin
 
 	for _, name := range sf.FileOrder {
 		layer := sf.internal[name]
-		if layer.WasLegacyImport() {
+		if layer.WasLegacyImport {
 			log.Warnf("'import' directive used in layer '%s' inside file '%s' is deprecated. "+
 				"Support for 'import' will be removed in releases after 2025-01-01. "+
 				"Migrate by changing 'import' to 'imports' and '/stacker' to '/stacker/imports'. "+

test/caching.bats

@@ -225,3 +225,36 @@ EOF
     echo '{"version": 1, "cache": "lolnope"}' > .stacker/build.cache
     stacker build --substitute BUSYBOX_OCI=${BUSYBOX_OCI}
 }
+
+@test "cache comparison of legacy import works across prereqs" {
+    echo "well, hi!"> helloworld
+
+    cat >> stacker-req.yaml << "EOF"
+base:
+    from:
+      type: oci
+      url: ${{BUSYBOX_OCI}}
+    build_only: true
+    import:
+        - helloworld
+    run: |
+      cp /stacker/helloworld /
+EOF
+
+cat >> stacker.yaml << "EOF"
+config:
+  prerequisites:
+      - stacker-req.yaml
+
+buildenv:
+    from:
+        type: built
+        tag: base
+    import:
+        - stacker://base/helloworld
+    run: |
+        cp /stacker/helloworld /h3
+
+EOF
+stacker --debug build --substitute BUSYBOX_OCI=${BUSYBOX_OCI}
+}