fix: Improve NAR file serving and remove old URL prefix workaround

pkg/cache/upstream/cache.go

@@ -381,10 +381,6 @@ func (c *Cache) GetNarInfo(ctx context.Context, hash string) (*narinfo.NarInfo,
 		ni.FileSize = ni.NarSize
 	}
 
-	// nix-serve serves the NarURL with the narinfo hash included in the URL as
-	// prefix to the NAR Hash. Trim that out, we don't need it.
-	ni.URL = strings.ReplaceAll(ni.URL, hash+"-", "")
-
 	return ni, nil
 }
 

testdata/nar7.go

@@ -14,7 +14,7 @@ var Nar7 = Entry{
 	NarInfoHash: "c12lxpykv6sld7a0sakcnr3y0la70x8w",
 	NarInfoPath: filepath.Join("c", "c1", "c12lxpykv6sld7a0sakcnr3y0la70x8w.narinfo"),
 	NarInfoText: `StorePath: /nix/store/c12lxpykv6sld7a0sakcnr3y0la70x8w-hello-2.12.2
-URL: nar/c12lxpykv6sld7a0sakcnr3y0la70x8w-09xizkfyvigl5fqs0dhkn46nghfwwijbpdzzl4zg6kx90prjmsg0.nar
+URL: nar/09xizkfyvigl5fqs0dhkn46nghfwwijbpdzzl4zg6kx90prjmsg0.nar
 Compression: none
 NarHash: sha256:1yf3p87fsqig07crd9sj9wh7i9jpsa0x86a22fqbls7c81lc7ws2
 NarSize: 113256

testdata/server.go

@@ -12,6 +12,7 @@ import (
 	"github.com/klauspost/compress/zstd"
 
 	"github.com/kalbasit/ncps/pkg/helper"
+	"github.com/kalbasit/ncps/pkg/nar"
 )
 
 type Server struct {
@@ -122,14 +123,43 @@ func (s *Server) handler() http.Handler {
 				bs = []byte(entry.NarInfoText)
 			}
 
+			// Support fetching narinfo by NAR hash (used by cache when only NAR hash is available)
+			if r.URL.Path == "/"+entry.NarHash+".narinfo" {
+				bs = []byte(entry.NarInfoText)
+			}
+
 			if r.URL.Path == "/nar/"+entry.NarHash+".nar" {
 				bs = []byte(entry.NarText)
 			}
 
-			if r.URL.Path == "/nar/"+entry.NarHash+".nar."+entry.NarCompression.ToFileExtension() {
+			// Build path with compression extension, only adding dot if extension is not empty
+			narPath := "/nar/" + entry.NarHash + ".nar"
+			if ext := entry.NarCompression.ToFileExtension(); ext != "" {
+				narPath += "." + ext
+			}
+
+			if r.URL.Path == narPath {
 				bs = []byte(entry.NarText)
 			}
 
+			// Support fetching by normalized hash (with prefix stripped)
+			normalizedHash := (&nar.URL{Hash: entry.NarHash}).Normalize().Hash
+			if normalizedHash != entry.NarHash {
+				if r.URL.Path == "/nar/"+normalizedHash+".nar" {
+					bs = []byte(entry.NarText)
+				}
+
+				// Build normalized path with compression extension
+				normalizedNarPath := "/nar/" + normalizedHash + ".nar"
+				if ext := entry.NarCompression.ToFileExtension(); ext != "" {
+					normalizedNarPath += "." + ext
+				}
+
+				if r.URL.Path == normalizedNarPath {
+					bs = []byte(entry.NarText)
+				}
+			}
+
 			if len(bs) > 0 {
 				if s := r.URL.Query().Get("fakesize"); s != "" {
 					size, err := strconv.Atoi(s)