update docker build (#272)

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

.drone.yml

@@ -35,7 +35,7 @@ pipeline:
     image: appleboy/golang-testing
     group: golang
     commands:
-      - make build
+      - make docker_build
 
   coverage:
     image: appleboy/golang-testing

Dockerfile

@@ -1,14 +1,8 @@
-# build stage
-FROM appleboy/golang-testing AS build-env
-ADD . /go/src/github.com/appleboy/gorush
-RUN cd /go/src/github.com/appleboy/gorush && make docker_build
-
-# final stage
 FROM centurylink/ca-certs
 EXPOSE 8088
 
 ADD config/config.yml /
-COPY --from=build-env /go/src/github.com/appleboy/gorush/bin/gorush /
+ADD bin/gorush /
 
 ENTRYPOINT ["/gorush"]
 CMD ["-c", "config.yml"]