refactor(tvix/nar-bridge): move pkg/server to pkg/http

This is only dealing with the HTTP interface.

Change-Id: I011b624fd9f11ea96231b92fea1166c118a219f2
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9535
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: Connor Brewster <cbrewster@hey.com>

tvix/nar-bridge/pkg/server/nar_get.go

@@ -1,219 +0,0 @@
-package server
-
-import (
-	"bytes"
-	"context"
-	"encoding/base64"
-	"encoding/hex"
-	"errors"
-	"fmt"
-	"io"
-	"io/fs"
-	"net/http"
-	"sync"
-
-	castorev1pb "code.tvl.fyi/tvix/castore/protos"
-	"code.tvl.fyi/tvix/nar-bridge/pkg/exporter"
-	storev1pb "code.tvl.fyi/tvix/store/protos"
-	"github.com/go-chi/chi/v5"
-	nixhash "github.com/nix-community/go-nix/pkg/hash"
-	"github.com/nix-community/go-nix/pkg/nixbase32"
-	log "github.com/sirupsen/logrus"
-)
-
-const (
-	narUrl = "/nar/{narhash:^([" + nixbase32.Alphabet + "]{52})$}.nar"
-)
-
-func renderNar(
-	ctx context.Context,
-	log *log.Entry,
-	directoryServiceClient castorev1pb.DirectoryServiceClient,
-	blobServiceClient castorev1pb.BlobServiceClient,
-	narHashToPathInfoMu *sync.Mutex,
-	narHashToPathInfo map[string]*storev1pb.PathInfo,
-	w io.Writer,
-	narHash *nixhash.Hash,
-	headOnly bool,
-) error {
-	// look in the lookup table
-	narHashToPathInfoMu.Lock()
-	pathInfo, found := narHashToPathInfo[narHash.SRIString()]
-	narHashToPathInfoMu.Unlock()
-
-	// if we didn't find anything, return 404.
-	if !found {
-		return fmt.Errorf("narHash not found: %w", fs.ErrNotExist)
-	}
-
-	// if this was only a head request, we're done.
-	if headOnly {
-		return nil
-	}
-
-	directories := make(map[string]*castorev1pb.Directory)
-
-	// If the root node is a directory, ask the directory service for all directories
-	if pathInfoDirectory := pathInfo.GetNode().GetDirectory(); pathInfoDirectory != nil {
-		rootDirectoryDigest := pathInfoDirectory.GetDigest()
-		log = log.WithField("root_directory", base64.StdEncoding.EncodeToString(rootDirectoryDigest))
-
-		directoryStream, err := directoryServiceClient.Get(ctx, &castorev1pb.GetDirectoryRequest{
-			ByWhat: &castorev1pb.GetDirectoryRequest_Digest{
-				Digest: rootDirectoryDigest,
-			},
-			Recursive: true,
-		})
-		if err != nil {
-			return fmt.Errorf("unable to query directory stream: %w", err)
-		}
-
-		// For now, we just stream all of these locally and put them into a hashmap,
-		// which is used in the lookup function below.
-		for {
-			directory, err := directoryStream.Recv()
-			if err != nil {
-				if err == io.EOF {
-					break
-				}
-				return fmt.Errorf("unable to receive from directory stream: %w", err)
-			}
-
-			// calculate directory digest
-			// TODO: do we need to do any more validation?
-			directoryDgst, err := directory.Digest()
-			if err != nil {
-				return fmt.Errorf("unable to calculate directory digest: %w", err)
-			}
-
-			log.WithField("directory", base64.StdEncoding.EncodeToString(directoryDgst)).Debug("received directory node")
-
-			directories[hex.EncodeToString(directoryDgst)] = directory
-		}
-
-	}
-
-	// render the NAR file
-	err := exporter.Export(
-		w,
-		pathInfo,
-		func(directoryDigest []byte) (*castorev1pb.Directory, error) {
-			log.WithField("directory", base64.StdEncoding.EncodeToString(directoryDigest)).Debug("Get directory")
-			directoryRefStr := hex.EncodeToString(directoryDigest)
-			directory, found := directories[directoryRefStr]
-			if !found {
-				return nil, fmt.Errorf(
-					"directory with hash %v does not exist: %w",
-					directoryDigest,
-					fs.ErrNotExist,
-				)
-			}
-
-			return directory, nil
-		},
-		func(blobDigest []byte) (io.ReadCloser, error) {
-			log.WithField("blob", base64.StdEncoding.EncodeToString(blobDigest)).Debug("Get blob")
-			resp, err := blobServiceClient.Read(ctx, &castorev1pb.ReadBlobRequest{
-				Digest: blobDigest,
-			})
-			if err != nil {
-				return nil, fmt.Errorf("unable to get blob: %w", err)
-			}
-
-			// set up a pipe, let a goroutine write, return the reader.
-			pR, pW := io.Pipe()
-
-			go func() {
-				for {
-					chunk, err := resp.Recv()
-					if errors.Is(err, io.EOF) {
-						break
-					}
-					if err != nil {
-						pW.CloseWithError(fmt.Errorf("receiving chunk: %w", err))
-						return
-					}
-
-					// write the received chunk to the writer part of the pipe
-					if _, err := io.Copy(pW, bytes.NewReader(chunk.GetData())); err != nil {
-						log.WithError(err).Error("writing chunk to pipe")
-						pW.CloseWithError(fmt.Errorf("writing chunk to pipe: %w", err))
-						return
-					}
-				}
-				pW.Close()
-
-			}()
-
-			return io.NopCloser(pR), nil
-		},
-	)
-	if err != nil {
-		return fmt.Errorf("unable to export nar: %w", err)
-	}
-	return nil
-}
-
-func registerNarGet(s *Server) {
-	// TODO: properly compose this
-	s.handler.Head(narUrl, func(w http.ResponseWriter, r *http.Request) {
-		defer r.Body.Close()
-
-		ctx := r.Context()
-
-		// parse the narhash sent in the request URL
-		narHash, err := parseNarHashFromUrl(chi.URLParamFromCtx(ctx, "narhash"))
-		if err != nil {
-			log.WithError(err).WithField("url", r.URL).Error("unable to decode nar hash from url")
-			w.WriteHeader(http.StatusBadRequest)
-			_, err := w.Write([]byte("unable to decode nar hash from url"))
-			if err != nil {
-				log.WithError(err).Errorf("unable to write error message to client")
-			}
-
-			return
-		}
-
-		log := log.WithField("narhash_url", narHash.SRIString())
-
-		err = renderNar(ctx, log, s.directoryServiceClient, s.blobServiceClient, &s.narHashToPathInfoMu, s.narHashToPathInfo, w, narHash, true)
-		if err != nil {
-			if errors.Is(err, fs.ErrNotExist) {
-				w.WriteHeader(http.StatusNotFound)
-			} else {
-				log.WithError(err).Warn("unable to render nar")
-				w.WriteHeader(http.StatusInternalServerError)
-			}
-		}
-
-	})
-	s.handler.Get(narUrl, func(w http.ResponseWriter, r *http.Request) {
-		defer r.Body.Close()
-
-		ctx := r.Context()
-
-		// parse the narhash sent in the request URL
-		narHash, err := parseNarHashFromUrl(chi.URLParamFromCtx(ctx, "narhash"))
-		if err != nil {
-			log.WithError(err).WithField("url", r.URL).Error("unable to decode nar hash from url")
-			w.WriteHeader(http.StatusBadRequest)
-			_, err := w.Write([]byte("unable to decode nar hash from url"))
-			if err != nil {
-				log.WithError(err).Errorf("unable to write error message to client")
-			}
-
-			return
-		}
-
-		log := log.WithField("narhash_url", narHash.SRIString())
-
-		err = renderNar(ctx, log, s.directoryServiceClient, s.blobServiceClient, &s.narHashToPathInfoMu, s.narHashToPathInfo, w, narHash, false)
-		if err != nil {
-			if errors.Is(err, fs.ErrNotExist) {
-				w.WriteHeader(http.StatusNotFound)
-			} else {
-				w.WriteHeader(http.StatusInternalServerError)
-			}
-		}
-	})
-}