builder: fix bugs when pruning buildkit cache with filters

Only the filters the user specified should be added as cache filters to buildkit.
Make an AND operation of the provided filters.
ID filter now does prefix-matching.

Signed-off-by: Tibor Vass <tibor@docker.com>

builder/builder-next/builder.go

@@ -530,20 +530,26 @@ func toBuildkitPruneInfo(opts types.BuildCachePruneOptions) (client.PruneInfo, e
 
 	bkFilter := make([]string, 0, opts.Filters.Len())
 	for cacheField := range cacheFields {
-		values := opts.Filters.Get(cacheField)
-		switch len(values) {
-		case 0:
-			bkFilter = append(bkFilter, cacheField)
-		case 1:
-			bkFilter = append(bkFilter, cacheField+"=="+values[0])
-		default:
-			return client.PruneInfo{}, errMultipleFilterValues
+		if opts.Filters.Include(cacheField) {
+			values := opts.Filters.Get(cacheField)
+			switch len(values) {
+			case 0:
+				bkFilter = append(bkFilter, cacheField)
+			case 1:
+				if cacheField == "id" {
+					bkFilter = append(bkFilter, cacheField+"~="+values[0])
+				} else {
+					bkFilter = append(bkFilter, cacheField+"=="+values[0])
+				}
+			default:
+				return client.PruneInfo{}, errMultipleFilterValues
+			}
 		}
 	}
 	return client.PruneInfo{
 		All:          opts.All,
 		KeepDuration: unusedFor,
 		KeepBytes:    opts.KeepStorage,
-		Filter:       bkFilter,
+		Filter:       []string{strings.Join(bkFilter, ",")},
 	}, nil
 }