cache: add fallback for snapshotID

tonistiigi · tonistiigi · commit b924f0b5ce5e · 2023-02-12T21:13:18.000-08:00
In older BuildKit versions snapshotID was not always set if record was not created with GetByBlob method. Old code defaulted to cache record ID in that case but that broke with the metadata interface refactor. Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com> (cherry picked from commit 2c0c429)
diff --git a/cache/metadata.go b/cache/metadata.go
@@ -251,7 +251,13 @@ func (md *cacheMetadata) queueMediaType(str string) error {
 }
 
 func (md *cacheMetadata) getSnapshotID() string {
-	return md.GetString(keySnapshot)
+	sid := md.GetString(keySnapshot)
+	// Note that historic buildkit releases did not always set the snapshot ID.
+	// Fallback to record ID is needed for old build cache compatibility.
+	if sid == "" {
+		return md.ID()
+	}
+	return sid
 }
 
 func (md *cacheMetadata) queueSnapshotID(str string) error {

Original file line number	Diff line number	Diff line change
`@@ -251,7 +251,13 @@ func (md *cacheMetadata) queueMediaType(str string) error {`
`251`	`251`	`}`
`252`	`252`
`253`	`253`	`func (md *cacheMetadata) getSnapshotID() string {`
`254`		`- return md.GetString(keySnapshot)`
	`254`	`+ sid := md.GetString(keySnapshot)`
	`255`	`+ // Note that historic buildkit releases did not always set the snapshot ID.`
	`256`	`+ // Fallback to record ID is needed for old build cache compatibility.`
	`257`	`+ if sid == "" {`
	`258`	`+ return md.ID()`
	`259`	`+ }`
	`260`	`+ return sid`
`255`	`261`	`}`
`256`	`262`
`257`	`263`	`func (md *cacheMetadata) queueSnapshotID(str string) error {`