mirror of
https://github.com/willnorris/imageproxy.git
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87 lines
2 KiB
Go
87 lines
2 KiB
Go
// Copyright 2013 The imageproxy authors.
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// SPDX-License-Identifier: Apache-2.0
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// Package gcscache provides an httpcache.Cache implementation that stores
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// cached values on Google Cloud Storage.
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package gcscache
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import (
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"context"
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"crypto/md5"
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"encoding/hex"
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"errors"
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"io"
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"log"
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"path"
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"cloud.google.com/go/storage"
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)
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var ctx = context.Background()
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type cache struct {
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bucket *storage.BucketHandle
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prefix string
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}
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func (c *cache) Get(key string) ([]byte, bool) {
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r, err := c.object(key).NewReader(ctx)
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if err != nil {
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if !errors.Is(err, storage.ErrObjectNotExist) {
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log.Printf("error reading from gcs: %v", err)
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}
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return nil, false
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}
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defer r.Close()
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value, err := io.ReadAll(r)
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if err != nil {
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log.Printf("error reading from gcs: %v", err)
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return nil, false
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}
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return value, true
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}
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func (c *cache) Set(key string, value []byte) {
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w := c.object(key).NewWriter(ctx)
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if _, err := w.Write(value); err != nil {
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log.Printf("error writing to gcs: %v", err)
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}
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if err := w.Close(); err != nil {
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log.Printf("error closing gcs object writer: %v", err)
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}
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}
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func (c *cache) Delete(key string) {
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if err := c.object(key).Delete(ctx); err != nil {
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log.Printf("error deleting gcs object: %v", err)
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}
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}
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func (c *cache) object(key string) *storage.ObjectHandle {
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name := path.Join(c.prefix, keyToFilename(key))
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return c.bucket.Object(name)
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}
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func keyToFilename(key string) string {
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h := md5.New()
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_, _ = io.WriteString(h, key)
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return hex.EncodeToString(h.Sum(nil))
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}
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// New constructs a Cache storing files in the specified GCS bucket. If prefix
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// is not empty, objects will be prefixed with that path. Credentials should
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// be specified using one of the mechanisms supported for Application Default
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// Credentials (see https://cloud.google.com/docs/authentication/production)
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func New(bucket, prefix string) (*cache, error) {
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client, err := storage.NewClient(ctx)
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if err != nil {
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return nil, err
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}
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return &cache{
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prefix: prefix,
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bucket: client.Bucket(bucket),
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}, nil
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}
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