NotAShelf/ncro
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server: route NAR requests via route cache; extract tryNARUpstream helper

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Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: Icd57a268015d58faa7ffc2b8c711283b6a6a6964
This commit is contained in:
raf 2026-03-06 22:08:46 +03:00
commit 118eda08a1
Signed by: NotAShelf
GPG key ID: 29D95B64378DB4BF
4 changed files with 114 additions and 44 deletions
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96
internal/server/server.go
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@ -10,6 +10,7 @@ import (
"time"
"github.com/prometheus/client_golang/prometheus/promhttp"
"notashelf.dev/ncro/internal/cache"
"notashelf.dev/ncro/internal/config"
"notashelf.dev/ncro/internal/metrics"
"notashelf.dev/ncro/internal/prober"
@ -18,19 +19,23 @@ import (
// HTTP handler implementing the Nix binary cache protocol.
type Server struct {
router *router.Router
prober *prober.Prober
upstreams []config.UpstreamConfig
client *http.Client
router *router.Router
prober *prober.Prober
db *cache.DB
upstreams []config.UpstreamConfig
client *http.Client
cachePriority int
}
// Creates a Server.
func New(r *router.Router, p *prober.Prober, upstreams []config.UpstreamConfig) *Server {
func New(r *router.Router, p *prober.Prober, db *cache.DB, upstreams []config.UpstreamConfig, cachePriority int) *Server {
return &Server{
router: r,
prober: p,
upstreams: upstreams,
client: &http.Client{Timeout: 60 * time.Second},
router: r,
prober: p,
db: db,
upstreams: upstreams,
client: &http.Client{Timeout: 60 * time.Second},
cachePriority: cachePriority,
}
}
@ -56,7 +61,7 @@ func (s *Server) handleCacheInfo(w http.ResponseWriter, _ *http.Request) {
w.Header().Set("Content-Type", "text/plain")
fmt.Fprintln(w, "StoreDir: /nix/store")
fmt.Fprintln(w, "WantMassQuery: 1")
fmt.Fprintln(w, "Priority: 30")
fmt.Fprintf(w, "Priority: %d\n", s.cachePriority)
}
func (s *Server) handleHealth(w http.ResponseWriter, _ *http.Request) {
@ -94,42 +99,57 @@ func (s *Server) handleNarinfo(w http.ResponseWriter, r *http.Request) {
func (s *Server) handleNAR(w http.ResponseWriter, r *http.Request) {
metrics.NARRequests.Inc()
sorted := s.prober.SortedByLatency()
if len(sorted) == 0 {
http.Error(w, "no upstreams available", http.StatusServiceUnavailable)
return
// Consult route cache: the narURL is the path without the leading slash.
narURL := strings.TrimPrefix(r.URL.Path, "/")
var tried string
if entry, err := s.db.GetRouteByNarURL(narURL); err == nil && entry != nil && entry.IsValid() {
tried = entry.UpstreamURL
if s.tryNARUpstream(w, r, entry.UpstreamURL) {
return
}
}
for _, h := range sorted {
if h.Status == prober.StatusDown {
// Fall back through all upstreams sorted by latency.
for _, h := range s.prober.SortedByLatency() {
if h.Status == prober.StatusDown || h.URL == tried {
continue
}
targetURL := h.URL + r.URL.Path
req, err := http.NewRequestWithContext(r.Context(), r.Method, targetURL, r.Body)
if err != nil {
continue
if s.tryNARUpstream(w, r, h.URL) {
return
}
for _, hdr := range []string{"Accept", "Accept-Encoding", "Range"} {
if v := r.Header.Get(hdr); v != "" {
req.Header.Set(hdr, v)
}
}
resp, err := s.client.Do(req)
if err != nil {
slog.Warn("NAR upstream failed", "upstream", h.URL, "error", err)
continue
}
if resp.StatusCode == http.StatusNotFound {
resp.Body.Close()
continue
}
defer resp.Body.Close()
slog.Debug("proxying NAR", "path", r.URL.Path, "upstream", h.URL)
s.copyResponse(w, resp)
return
}
http.NotFound(w, r)
}
// Attempts to serve a NAR from upstreamBase. Returns true if the upstream
// responded with a non-404 status.
func (s *Server) tryNARUpstream(w http.ResponseWriter, r *http.Request, upstreamBase string) bool {
targetURL := upstreamBase + r.URL.Path
req, err := http.NewRequestWithContext(r.Context(), r.Method, targetURL, r.Body)
if err != nil {
return false
}
for _, hdr := range []string{"Accept", "Accept-Encoding", "Range"} {
if v := r.Header.Get(hdr); v != "" {
req.Header.Set(hdr, v)
}
}
resp, err := s.client.Do(req)
if err != nil {
slog.Warn("NAR upstream failed", "upstream", upstreamBase, "error", err)
return false
}
if resp.StatusCode == http.StatusNotFound {
resp.Body.Close()
return false
}
defer resp.Body.Close()
slog.Debug("proxying NAR", "path", r.URL.Path, "upstream", upstreamBase)
s.copyResponse(w, resp)
return true
}
// Forwards r to targetURL and streams the response zero-copy.
func (s *Server) proxyRequest(w http.ResponseWriter, r *http.Request, targetURL string) {
req, err := http.NewRequestWithContext(r.Context(), r.Method, targetURL, r.Body)