add GCS cache

README.md

@@ -102,6 +102,9 @@ enabled using the `-cache` flag.  It supports the following values:
    images on Amazon S3.  This requires either an IAM role and instance profile
    with access to your your bucket or `AWS_ACCESS_KEY_ID` and `AWS_SECRET_KEY`
    environmental parameters set.
+ - GCS URL (e.g. `gcs://bucket-name/optional-path-prefix`) - will cache
+   images on Google Cloud Storage.  This requires `GCP_PRIVATE_KEY` environmental
+   parameters set.
 
 For example, to cache files on disk in the `/tmp/imageproxy` directory:
 

cmd/imageproxy/main.go

@@ -24,6 +24,7 @@ import (
 	"net/url"
 	"strings"
 
+	"github.com/diegomarangoni/gcscache"
 	"github.com/gregjones/httpcache"
 	"github.com/gregjones/httpcache/diskcache"
 	"github.com/peterbourgon/diskv"
@@ -126,6 +127,8 @@ func parseCache() (imageproxy.Cache, error) {
 	case "s3":
 		u.Scheme = "https"
 		return s3cache.New(u.String()), nil
+	case "gcs":
+		return gcscache.New(u.String()), nil
 	case "file":
 		fallthrough
 	default: