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imageproxy/internal/s3cache/s3cache.go

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// Package s3cache provides an httpcache.Cache implementation that stores
// cached values on Amazon S3.
package s3cache
import (
"bytes"
"crypto/md5"
"encoding/hex"
"io"
"io/ioutil"
"log"
"net/url"
"path"
"strings"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/awserr"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/s3"
)
type cache struct {
*s3.S3
bucket, prefix string
}
func (c *cache) Get(key string) ([]byte, bool) {
key = path.Join(c.prefix, keyToFilename(key))
input := &s3.GetObjectInput{
Bucket: &c.bucket,
Key: &key,
}
resp, err := c.GetObject(input)
if err != nil {
if aerr, ok := err.(awserr.Error); ok && aerr.Code() != "NoSuchKey" {
log.Printf("error fetching from s3: %v", aerr)
}
return nil, false
}
value, err := ioutil.ReadAll(resp.Body)
if err != nil {
log.Printf("error reading s3 response body: %v", err)
return nil, false
}
return value, true
}
func (c *cache) Set(key string, value []byte) {
key = path.Join(c.prefix, keyToFilename(key))
input := &s3.PutObjectInput{
Body: aws.ReadSeekCloser(bytes.NewReader(value)),
Bucket: &c.bucket,
Key: &key,
}
_, err := c.PutObject(input)
if err != nil {
log.Printf("error writing to s3: %v", err)
}
}
func (c *cache) Delete(key string) {
key = path.Join(c.prefix, keyToFilename(key))
input := &s3.DeleteObjectInput{
Bucket: &c.bucket,
Key: &key,
}
_, err := c.DeleteObject(input)
if err != nil {
log.Printf("error deleting from s3: %v", err)
}
}
func keyToFilename(key string) string {
h := md5.New()
io.WriteString(h, key)
return hex.EncodeToString(h.Sum(nil))
}
// New constructs a cache configured using the provided URL string. URL should
// be of the form: "s3://region/bucket/optional-path-prefix". Credentials
// should be specified using one of the mechanisms supported by aws-sdk-go (see
// https://docs.aws.amazon.com/sdk-for-go/api/aws/session/).
func New(s string) (*cache, error) {
u, err := url.Parse(s)
if err != nil {
return nil, err
}
region := u.Host
path := strings.SplitN(strings.TrimPrefix(u.Path, "/"), "/", 2)
bucket := path[0]
var prefix string
if len(path) > 1 {
prefix = path[1]
}
config := aws.NewConfig().WithRegion(region)
// allow overriding some additional config options, mostly useful when
// working with s3-compatible services other than AWS.
if v := u.Query().Get("endpoint"); v != "" {
config = config.WithEndpoint(v)
}
if v := u.Query().Get("disableSSL"); v == "1" {
config = config.WithDisableSSL(true)
}
if v := u.Query().Get("s3ForcePathStyle"); v == "1" {
config = config.WithS3ForcePathStyle(true)
}
sess, err := session.NewSession(config)
if err != nil {
return nil, err
}
return &cache{
S3: s3.New(sess),
bucket: bucket,
prefix: prefix,
}, nil
}