depot/go/nix/nixbuild/httpresolver.go

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2023-08-23 23:00:44 +00:00
// SPDX-FileCopyrightText: 2023 Luke Granger-Brown <depot@lukegb.com>
//
// SPDX-License-Identifier: Apache-2.0
package nixbuild
import (
"context"
"fmt"
"io"
"net/http"
"os"
"regexp"
"github.com/numtide/go-nix/nixbase32"
"hg.lukegb.com/lukegb/depot/go/nix/nar/narinfo"
)
var (
hashExtractRegexp = regexp.MustCompile(`(^|/)([0-9a-df-np-sv-z]{32})([-.].*)?$`)
)
func hashExtract(s string) string {
res := hashExtractRegexp.FindStringSubmatch(s)
if len(res) == 0 {
return ""
}
return res[2]
}
func keyForPath(storePath string) (string, error) {
fileHash := hashExtract(storePath)
if fileHash == "" {
return "", fmt.Errorf("store path %v seems to be invalid: couldn't extract hash", storePath)
}
return fmt.Sprintf("%s.narinfo", fileHash), nil
}
type HTTPCacheResolver struct {
Endpoint string
HTTPClient *http.Client
Priority int
}
var _ Resolver = ((*HTTPCacheResolver)(nil))
func (r *HTTPCacheResolver) RelativePriority() int { return r.Priority }
func (r *HTTPCacheResolver) FetchNarInfo(ctx context.Context, path string) (*narinfo.NarInfo, error) {
key, err := keyForPath(path)
if err != nil {
return nil, err
}
req, err := http.NewRequestWithContext(ctx, "GET", fmt.Sprintf("%v/%v", r.Endpoint, key), nil)
if err != nil {
return nil, fmt.Errorf("constructing request for %v/%v: %v", r.Endpoint, key, err)
}
resp, err := http.DefaultClient.Do(req)
if err != nil {
return nil, fmt.Errorf("making request for %v/%v: %v", r.Endpoint, key, err)
}
defer resp.Body.Close()
switch resp.StatusCode {
case http.StatusNotFound:
return nil, os.ErrNotExist
case http.StatusOK:
// continue with function
default:
return nil, fmt.Errorf("%v/%v: HTTP %v", r.Endpoint, key, resp.Status)
}
return narinfo.ParseNarInfo(resp.Body)
}
func (r *HTTPCacheResolver) FetchNar(ctx context.Context, ni *narinfo.NarInfo) (io.ReadCloser, error) {
compressionSuffix, err := ni.Compression.FileSuffix()
if err != nil {
return nil, fmt.Errorf("determining filename: %w", err)
}
key := fmt.Sprintf("nar/%s.nar%s", nixbase32.EncodeToString(ni.FileHash.Hash), compressionSuffix)
req, err := http.NewRequestWithContext(ctx, "GET", fmt.Sprintf("%v/%v", r.Endpoint, key), nil)
if err != nil {
return nil, fmt.Errorf("constructing request for %v/%v: %v", r.Endpoint, key, err)
}
resp, err := http.DefaultClient.Do(req)
if err != nil {
return nil, fmt.Errorf("making request for %v/%v: %v", r.Endpoint, key, err)
}
switch resp.StatusCode {
case http.StatusNotFound:
resp.Body.Close()
return nil, os.ErrNotExist
case http.StatusOK:
return resp.Body, nil
default:
resp.Body.Close()
return nil, fmt.Errorf("downloading %v/%v: HTTP status code %v", r.Endpoint, key, resp.Status)
}
}