Add support for bucket object --folder option.

.gitignore

@@ -11,6 +11,9 @@ _test
 *.[568vq]
 [568vq].out
 
+# IDE settings
+.idea/
+
 *.cgo1.go
 *.cgo2.c
 _cgo_defun.c

README.md

@@ -49,3 +49,55 @@ docker run --rm \
   -w $(pwd) \
   plugins/gcs
 ```
+
+#### Optional object folder setting
+
+The object folder can be specified as part of the `PLUGIN_TARGET` or as part of the `PLUGIN_FOLDER` setting. The value
+of the `PLUGIN_FOLDER` setting will be appended to any value supplied as part of the `PLUGIN_TARGET`.
+
+```console
+docker run --rm \
+  -e PLUGIN_SOURCE="dist" \
+  -e PLUGIN_TARGET="bucket/dir/" \
+  -e PLUGIN_FOLDER="${DRONE_PULL_REQUEST}" \
+  -e PLUGIN_IGNORE="bin/*" \
+  -e PLUGIN_ACL="allUsers:READER,[email protected]:OWNER" \
+  -e PLUGIN_GZIP="js,css,html" \
+  -e PLUGIN_CACHE_CONTROL="public,max-age=3600" \
+  -e PLUGIN_METADATA='{"x-goog-meta-foo":"bar"}' \
+  -v $(pwd):$(pwd) \
+  -w $(pwd) \
+  plugins/gcs
+```
+
+One potential use case for specifying the `PLUGIN_FOLDER` separately is when storing the value for `PLUGIN_TARGET` as a
+drone secret while needing to generate a final object folder value during CI. The above example illustrates how it may
+be possible to publish to `bucket/dir/DRONE_PULL_REQUEST`.
+
+Perhaps a more illustrative example:
+
+```yaml
+kind: pipeline
+name: upload prs
+
+trigger:
+  branch:
+    include:
+      - develop
+  event:
+    - pull_request
+
+steps: 
+  - name: upload to cloud storage prs bucket
+    image: plugins/gcs
+    settings:
+      source: build
+      target:
+        from_secret: prs_bucket
+      folder: "prs/${DRONE_PULL_REQUEST}"
+      gzip: js,css,html
+      token:
+        from_secret: prs_token
+```
+
+The above drone configuration file is not meant to be complete.

go.mod

@@ -4,16 +4,19 @@ go 1.15
 
 require (
 	cloud.google.com/go v0.21.0
-	github.com/golang/protobuf v1.0.0
-	github.com/googleapis/gax-go v2.0.0+incompatible
+	github.com/golang/glog v0.0.0-20210429001901-424d2337a529 // indirect
+	github.com/golang/protobuf v1.0.0 // indirect
+	github.com/google/go-cmp v0.5.6 // indirect
+	github.com/googleapis/gax-go v2.0.0+incompatible // indirect
 	github.com/pkg/errors v0.8.0
 	github.com/urfave/cli v1.20.0
-	go.opencensus.io v0.8.0
+	go.opencensus.io v0.8.0 // indirect
 	golang.org/x/net v0.0.0-20180415214307-500e7a4f953d
 	golang.org/x/oauth2 v0.0.0-20180402223937-921ae394b943
-	golang.org/x/text v0.3.0
+	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c // indirect
+	golang.org/x/text v0.3.0 // indirect
 	google.golang.org/api v0.0.0-20180413000347-fca24fcb4112
-	google.golang.org/appengine v1.0.0
-	google.golang.org/genproto v0.0.0-20180413175816-7fd901a49ba6
-	google.golang.org/grpc v1.11.3
+	google.golang.org/appengine v1.0.0 // indirect
+	google.golang.org/genproto v0.0.0-20180413175816-7fd901a49ba6 // indirect
+	google.golang.org/grpc v1.11.3 // indirect
 )

go.sum

@@ -1,7 +1,11 @@
 cloud.google.com/go v0.21.0 h1:083TLU7hqb1CzKeMhzDsCTP4uXkBGr6nnWuaHdVNBCI=
 cloud.google.com/go v0.21.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
+github.com/golang/glog v0.0.0-20210429001901-424d2337a529 h1:2voWjNECnrZRbfwXxHB1/j8wa6xdKn85B5NzgVL/pTU=
+github.com/golang/glog v0.0.0-20210429001901-424d2337a529/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
 github.com/golang/protobuf v1.0.0 h1:lsek0oXi8iFE9L+EXARyHIjU5rlWIhhTkjDz3vHhWWQ=
 github.com/golang/protobuf v1.0.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/google/go-cmp v0.5.6 h1:BKbKCqvP6I+rmFHt06ZmyQtvB8xAkWdhFyr0ZUNZcxQ=
+github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/googleapis/gax-go v2.0.0+incompatible h1:j0GKcs05QVmm7yesiZq2+9cxHkNK9YM6zKx4D2qucQU=
 github.com/googleapis/gax-go v2.0.0+incompatible/go.mod h1:SFVmujtThgffbyetf+mdk2eWhX2bMyUtNHzFKcPA9HY=
 github.com/pkg/errors v0.8.0 h1:WdK/asTD0HN+q6hsWO3/vpuAkAr+tw6aNJNDFFf0+qw=
@@ -14,10 +18,15 @@ golang.org/x/net v0.0.0-20180415214307-500e7a4f953d h1:YbPBOQdSo5fFDiZgBDcltE4Xj
 golang.org/x/net v0.0.0-20180415214307-500e7a4f953d/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/oauth2 v0.0.0-20180402223937-921ae394b943 h1:hE+k6oRG1aru6/y8A0HI01Zqp65EZcUcKToTkbPsFFM=
 golang.org/x/oauth2 v0.0.0-20180402223937-921ae394b943/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c h1:5KslGYwFpkhGh+Q16bwMP3cOontH8FOep7tGV86Y7SQ=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/api v0.0.0-20180413000347-fca24fcb4112 h1:ZwIBv243B9oUEb2HVMTQs//+WVhsL5hsUoCAu1ydobs=
 google.golang.org/api v0.0.0-20180413000347-fca24fcb4112/go.mod h1:4mhQ8q/RsB7i+udVvVy5NUi08OU8ZlA0gRVgrF7VFY0=
+google.golang.org/appengine v1.0.0 h1:dN4LljjBKVChsv0XCSI+zbyzdqrkEwX5LQFUMRSGqOc=
 google.golang.org/appengine v1.0.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=
 google.golang.org/genproto v0.0.0-20180413175816-7fd901a49ba6 h1:VrRtqEIrO5wUzNwL/A2WTNUtDuAtvb3KPK3OrUriLqI=
 google.golang.org/genproto v0.0.0-20180413175816-7fd901a49ba6/go.mod h1:JiN7NxoALGmiZfu7CAH4rXhgtRTLTxftemlI0sWmxmc=

main.go

@@ -52,9 +52,14 @@ func main() {
 		},
 		cli.StringFlag{
 			Name:   "target",
-			Usage:  "destination to copy files to, including bucket name",
+			Usage:  "destination bucket to copy files to, can include folder path",
 			EnvVar: "PLUGIN_TARGET",
 		},
+		cli.StringFlag{
+			Name:   "folder",
+			Usage:  "destination folder path to copy files to, will be appended to target",
+			EnvVar: "PLUGIN_FOLDER",
+		},
 		cli.StringSliceFlag{
 			Name:   "gzip",
 			Usage:  `files with the specified extensions will be gzipped and uploaded with "gzip" Content-Encoding header`,
@@ -84,6 +89,7 @@ func run(c *cli.Context) error {
 			ACL:          c.StringSlice("acl"),
 			Source:       c.String("source"),
 			Target:       c.String("target"),
+			Folder:       c.String("folder"),
 			Ignore:       c.String("ignore"),
 			Gzip:         c.StringSlice("gzip"),
 			CacheControl: c.String("cache-control"),

plugin.go

@@ -30,9 +30,12 @@ type (
 		// Copies the files from the specified directory.
 		Source string
 
-		// Destination to copy files to, including bucket name
+		// Destination bucket to copy files to, can include folder path
 		Target string
 
+		// Destination folder path to copy files to, will be appended to target
+		Folder string
+
 		// Exclude files matching this pattern.
 		Ignore string
 
@@ -113,11 +116,11 @@ func (p *Plugin) Exec(client *storage.Client) error {
 			rel, err := filepath.Rel(p.Config.Source, f)
 
 			if err != nil {
-				res <- &result{f, err}
+				res <- &result{rel, err}
 				return
 			}
 
-			err = p.uploadFile(path.Join(p.Config.Target, rel), f)
+			err = p.uploadFile(f)
 			res <- &result{rel, err}
 
 			<-buf // free up
@@ -146,23 +149,38 @@ func (p *Plugin) errorf(format string, args ...interface{}) {
 	p.printf(format, args...)
 }
 
-// uploadFile uploads the file to dst using global bucket.
+// objectFolderPath returns a bucket object folder name based on plugin target and folder values.
+// It is intended that the bucket name has already been stripped from the target.
+func (p *Plugin) objectFolderPath() string {
+	return path.Join(p.Config.Target, p.Config.Folder)
+}
+
+// objectFolderPathForFile returns a bucket object name including a resolved object folder path.
+func (p *Plugin) objectFolderPathForFile(file string) (string, error) {
+	rel, err := filepath.Rel(p.Config.Source, file)
+
+	if err != nil {
+		return "", err
+	}
+
+	return path.Join(p.objectFolderPath(), rel), nil
+}
+
+// uploadFile uploads the file, relative to plugin source directory, to dst using global bucket.
 // To get a more robust upload use retryUpload instead.
-func (p *Plugin) uploadFile(dst, file string) error {
+func (p *Plugin) uploadFile(file string) error {
 	r, gz, err := p.gzipper(file)
 
 	if err != nil {
 		return err
 	}
 
 	defer r.Close()
-	rel, err := filepath.Rel(p.Config.Source, file)
 
+	name, err := p.objectFolderPathForFile(file)
 	if err != nil {
 		return err
 	}
-
-	name := path.Join(p.Config.Target, rel)
 	w := p.bucket.Object(name).NewWriter(context.Background())
 	w.CacheControl = p.Config.CacheControl
 	w.Metadata = p.Config.Metadata