support tag string.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

README.md

@@ -77,6 +77,7 @@ docker run --rm \
   -e DRONE_BUILD_NUMBER=1 \
   -e DRONE_BUILD_STATUS=success \
   -e DRONE_BUILD_LINK=http://github.com/appleboy/go-hello \
+  -e DRONE_TAG=1.0.0 \
   -e DRONE_JOB_STARTED=1477550550 \
   -e DRONE_JOB_FINISHED=1477550750 \
   -v $(pwd):$(pwd) \

main.go

@@ -147,6 +147,11 @@ func main() {
 			Usage:  "build link",
 			EnvVar: "DRONE_BUILD_LINK",
 		},
+		cli.StringFlag{
+			Name:   "build.tag",
+			Usage:  "build tag",
+			EnvVar: "DRONE_TAG",
+		},
 		cli.Float64Flag{
 			Name:   "job.started",
 			Usage:  "job started",
@@ -177,6 +182,7 @@ func run(c *cli.Context) error {
 			Name:  c.String("repo.name"),
 		},
 		Build: Build{
+			Tag:      c.String("build.tag"),
 			Number:   c.Int("build.number"),
 			Event:    c.String("build.event"),
 			Status:   c.String("build.status"),

plugin.go

@@ -21,6 +21,7 @@ type (
 
 	// Build information.
 	Build struct {
+		Tag      string
 		Event    string
 		Number   int
 		Commit   string

plugin_test.go

@@ -56,6 +56,7 @@ func TestSendMessage(t *testing.T) {
 			Owner: "appleboy",
 		},
 		Build: Build{
+			Tag:     "1.0.0",
 			Number:  101,
 			Status:  "success",
 			Link:    "https://github.com/appleboy/go-hello",