feat: allow mapping hashes to subdomains (#48)

This is useful for static sites that use absolute paths.

If $DOMAIN is set, also map `<nar-hash>.$DOMAIN`

README.md

@@ -48,6 +48,7 @@ You can use the following environment variables to configure nar-serve:
 | `PORT` | `8383` | Port number on which nar-service listens |
 | `HTTP_ADDR` | `:$PORT` | HTTP address to bind the server to. When set, takes precedence over $PORT. |
 | `NIX_CACHE_URL` | `https://cache.nixos.org` | The URL of the Nix store from which NARs are fetched |
+| `DOMAIN` | "" | When set, also serve `<nar-hash>.$DOMAIN` paths. |
 
 ## Contributing
 

api/unpack/index.go

@@ -4,6 +4,7 @@ import (
 	"compress/bzip2"
 	"context"
 	"fmt"
+	"log"
 	"io"
 	"mime"
 	"net/http"
@@ -14,6 +15,7 @@ import (
 	"github.com/numtide/nar-serve/pkg/nar"
 	"github.com/numtide/nar-serve/pkg/narinfo"
 
+	"github.com/go-chi/chi/v5"
 	"github.com/klauspost/compress/zstd"
 	"github.com/ulikunitz/xz"
 )
@@ -37,34 +39,44 @@ func (h *Handler) MountPath() string {
 
 // Handler is the entry-point for @now/go as well as the stub main.go net/http
 func (h *Handler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
-	ctx := req.Context()
-	// remove the mount path from the path
-	path := strings.TrimPrefix(req.URL.Path, h.mountPath)
-	// ignore trailing slashes
-	path = strings.TrimRight(path, "/")
-
-	components := strings.Split(path, "/")
-	if len(components) == 0 {
+	narDir := chi.URLParam(req, "narDir")
+	if narDir == "" {
 		w.Header().Set("Content-Type", "text/plain")
 		http.Error(w, "store path missing", 404)
 		return
 	}
-	fmt.Println(len(components), components)
 
-	narDir := components[0]
-	narName := strings.Split(narDir, "-")[0]
+	narHash := strings.Split(narDir, "-")[0]
+
+	h.ServeNAR(narHash, w, req)
+}
+
+func (h *Handler) ServeNAR(narHash string, w http.ResponseWriter, req *http.Request) {
+	ctx := req.Context()
+
+	log.Println("narHash=", narHash)
+
+	// Do some path cleanup
+	// ignore trailing slashes
+	newPath := strings.TrimRight(req.URL.Path, "/")
+	// remove the mount path and nar hash from the path
+	if strings.HasPrefix(newPath, h.mountPath) {
+		components := strings.Split(newPath, "/")
+		newPath = strings.Join(components[4:], "/")
+	}
+	newPath = "/" + strings.TrimLeft(newPath, "/")
+	log.Println("newPath=", newPath)
 
 	// Get the NAR info to find the NAR
-	narinfo, err := getNarInfo(ctx, h.cache, narName)
+	narinfo, err := getNarInfo(ctx, h.cache, narHash)
 	if err != nil {
 		http.Error(w, err.Error(), 500)
 		return
 	}
-	fmt.Println("narinfo", narinfo)
 
 	// TODO: consider keeping a LRU cache
 	narPATH := narinfo.URL
-	fmt.Println("fetching the NAR:", narPATH)
+	log.Println("fetching the NAR:", narPATH)
 	file, err := h.cache.GetFile(ctx, narPATH)
 	if err != nil {
 		http.Error(w, err.Error(), 500)
@@ -104,10 +116,6 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 		return
 	}
 
-	newPath := "/" + strings.Join(components[1:], "/")
-
-	fmt.Println("newPath", newPath)
-
 	for {
 		hdr, err := narReader.Next()
 		if err != nil {

default.nix

@@ -7,7 +7,7 @@ rec {
     pname = "nar-serve";
     version = "latest";
     src = nixpkgs.lib.cleanSource ./.;
-    vendorHash = "sha256-hi0KK+TQ3JG6LSMy8wnLDBRnTCwlfwo3ru22sbgX7dc=";
+    vendorHash = "sha256-td9NYHGYJYPlIj2tnf5I/GnJQOOgODc6TakHFwxyvLQ=";
     doCheck = false;
   };
 

go.mod

@@ -8,6 +8,7 @@ require (
 	cloud.google.com/go/storage v1.43.0
 	github.com/aws/aws-sdk-go v1.55.3
 	github.com/go-chi/chi/v5 v5.1.0
+	github.com/go-chi/hostrouter v0.2.0
 	github.com/google/go-cmp v0.6.0
 	github.com/klauspost/compress v1.17.9
 	github.com/stretchr/testify v1.9.0

go.sum

@@ -30,6 +30,8 @@ github.com/felixge/httpsnoop v1.0.4 h1:NFTV2Zj1bL4mc9sqWACXbQFVBBg2W3GPvqp8/ESS2
 github.com/felixge/httpsnoop v1.0.4/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
 github.com/go-chi/chi/v5 v5.1.0 h1:acVI1TYaD+hhedDJ3r54HyA6sExp3HfXq7QWEEY/xMw=
 github.com/go-chi/chi/v5 v5.1.0/go.mod h1:DslCQbL2OYiznFReuXYUmQ2hGd1aDpCnlMNITLSKoi8=
+github.com/go-chi/hostrouter v0.2.0 h1:GwC7TZz8+SlJN/tV/aeJgx4F+mI5+sp+5H1PelQUjHM=
+github.com/go-chi/hostrouter v0.2.0/go.mod h1:pJ49vWVmtsKRKZivQx0YMYv4h0aX+Gcn6V23Np9Wf1s=
 github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
 github.com/go-logr/logr v1.4.2 h1:6pFjapn8bFcIbiKo3XT4j/BhANplGihG6tvd+8rYgrY=
 github.com/go-logr/logr v1.4.2/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=

main.go

@@ -2,17 +2,20 @@ package main
 
 import (
 	"context"
-	"log"
 	_ "embed"
+	"log"
 	"net/http"
-	"text/template"
 	"os"
+	"strings"
+	"text/template"
 
-	"github.com/numtide/nar-serve/pkg/libstore"
 	"github.com/numtide/nar-serve/api/unpack"
+	"github.com/numtide/nar-serve/pkg/libstore"
+	"github.com/numtide/nar-serve/pkg/nixhash"
 
 	"github.com/go-chi/chi/v5"
 	"github.com/go-chi/chi/v5/middleware"
+	"github.com/go-chi/hostrouter"
 )
 
 //go:embed views/index.html
@@ -37,6 +40,7 @@ func main() {
 		port        = getEnv("PORT", "8383")
 		addr        = getEnv("HTTP_ADDR", "")
 		nixCacheURL = getEnv("NIX_CACHE_URL", getEnv("NAR_CACHE_URL", "https://cache.nixos.org"))
+		domain      = getEnv("DOMAIN", "")
 	)
 
 	if addr == "" {
@@ -49,29 +53,58 @@ func main() {
 	}
 
 	// FIXME: get the mountPath from the binary cache /nix-cache-info file
-	h := unpack.NewHandler(cache, "/nix/store/")
+	storeHandler := unpack.NewHandler(cache, "/nix/store/")
 
 	r := chi.NewRouter()
-
 	r.Use(middleware.RequestID)
 	r.Use(middleware.Logger)
 	r.Use(middleware.Recoverer)
 	r.Use(middleware.CleanPath)
 	r.Use(middleware.GetHead)
 
-	r.Get("/", func(w http.ResponseWriter, r *http.Request) {
+	defaultRouter := chi.NewRouter()
+	defaultRouter.Get("/", func(w http.ResponseWriter, r *http.Request) {
 		data := struct {
 			NixCacheURL string
-		}{ nixCacheURL }
+		}{nixCacheURL}
 
 		if err := indexHTMLTmpl.Execute(w, data); err != nil {
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 		}
 	})
-	r.Get("/healthz", healthzHandler)
-	r.Get("/robots.txt", robotsHandler)
-	r.Method("GET", h.MountPath()+"*", h)
+	defaultRouter.Get("/healthz", healthzHandler)
+	defaultRouter.Get("/robots.txt", robotsHandler)
+	defaultRouter.Method("GET", storeHandler.MountPath()+"{narDir}", storeHandler)
+	defaultRouter.Method("GET", storeHandler.MountPath()+"{narDir}/*", storeHandler)
+
+	if domain != "" {
+		narRouter := chi.NewRouter()
+		narRouter.Get("/*", func(w http.ResponseWriter, r *http.Request) {
+			// First try to find a nix hash in a subdomain.
+			narHash := getSubdomain(r.Host)
+			algo := nixhash.SHA1
+			_, err := nixhash.ParseAny(narHash, &algo)
+			if err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+				return
+			}
+
+			log.Println("subdomain narHash", narHash)
+			storeHandler.ServeNAR(narHash, w, r)
+		})
+
+		hr := hostrouter.New()
+		hr.Map("*", defaultRouter) // default
+		hr.Map("*."+domain, narRouter)
+
+		r.Mount("/", hr)
+	} else {
+		r.Mount("/", defaultRouter)
+	}
+
+	// Front the naked muxer with one that matches sub-domains
 
+	log.Println("domain=", domain)
 	log.Println("nixCacheURL=", nixCacheURL)
 	log.Println("addr=", addr)
 	log.Fatal(http.ListenAndServe(addr, r))
@@ -84,3 +117,11 @@ func getEnv(name, def string) string {
 	}
 	return value
 }
+
+func getSubdomain(host string) string {
+	parts := strings.Split(host, ".")
+	if len(parts) > 1 {
+		return parts[0]
+	}
+	return ""
+}