fix Dockerfile

Author: x1unix

build/Dockerfile

@@ -1,8 +1,10 @@
 FROM node:13-alpine as ui-build
-COPY web .
+COPY web /tmp/web
+WORKDIR /tmp/web
 RUN yarn install --silent && yarn build
 
 FROM golang:1.13-alpine as build
+WORKDIR /tmp/playground
 COPY cmd ./cmd
 COPY pkg ./pkg
 COPY go.mod .
@@ -11,8 +13,9 @@ RUN go build -o server ./cmd/playground
 
 FROM golang:1.13-alpine as production
 WORKDIR /opt/playground
+ENV GOROOT /usr/local/go
 COPY data ./data
-COPY --from=ui-build web/build ./public
-COPY --from=build server .
+COPY --from=ui-build /tmp/web/build ./public
+COPY --from=build /tmp/playground/server .
 EXPOSE 8000
-CMD ['/opt/playground/server', '-f=/opt/playground/data/packages.json']
+ENTRYPOINT ["/opt/playground/server", "-f=/opt/playground/data/packages.json"]